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Bulk Electric System

Facility Rating Methodology

TRANSMISSION

Revisions

|Rev. | | | | |

|No. |Date |Description |By |Approval |

|0 |2/18/00 |New Document |DCS/JWS |RDC |

|1 |11/1/04 |Rev. for FRCC 2004 Compliance Program with 2001 NERC Planning |DCS/JWS |JJM |

| | |Standards; added series and shunt reactive elements | | |

|2 |8/25/05 |Reformatted & added document number; rev 3.4 - added OPGW; rev 4.3 – |DCS |JJM |

| | |added specific criteria; added Appendix A – Generator rating. | | |

|3 |10/14/05 |Rev. 4.8 – Fault current methodology. |DCS |JJM |

|4 |2/28/07 |Reformatted & revised throughout, updated conductor methodology, |DCS/JJM/MCW/JAZ |JJM |

| | |added GSU, updated generator methodology. | | |

|5 |7/01/08 |Reformatted & revised throughout. Added Emergency Ratings |RAC/MDJ/ |JJM |

| | |methodologies. |JJM/NCA | |

|6 |9/29/08 |Deleted Appendix A. Generation Document will be posted separately. |BJM |BJM |

|7 |6/29/09 |Reformatted and revised throughout. |GJK |MDJ |

| | |Drawing number A-214381 is voided/cancelled. This document will be | | |

| | |maintained in Documentum with a copy in the Operational Model. It | | |

| | |will also be posted on FPL’s OASIS. | | |

Table of Contents

1. Introduction 4

2. Bulk Electric System Facilities 5

2.1 Transmission Line Facilities 5

2.2 Transformer Facilities 6

2.3 Series and Shunt Compensation Facilities 6

3. Major Equipment Ratings 7

3.1 Underground Transmission Cable 7

3.2 Overhead Transmission Conductors 8

3.3 Autotransformers 11

3.4 Generator Step-Up Transformers (GSU’s) 12

3.5 Shunt Capacitors 13

3.6 Shunt Reactors 13

3.7 Series Capacitors 14

3.8 Series Reactors 14

4. Terminal Equipment and Relay Protective Device Ratings 15

4.1 Substation Conductors 15

4.2 Circuit Breakers 17

4.3 Instrument Transformers 18

4.3.1 Current Transformers 18

4.3.2 Voltage Transformers 19

4.4 Air Disconnect Switches 20

4.5 Circuit Switchers 22

4.6 Line Traps 23

4.7 Relay Protective Devices 24

1. Introduction

This document describes the methodology that Florida Power & Light Company (FPL) uses to determine the Facility Rating[1] of certain Bulk Electric System (BES) Facilities[2] (Facilities) as required by NERC/FERC Reliability Standard FAC-008-1[3]. The methodology described herein covers Facilities solely owned by FPL and Facilities jointly owned for which FPL has responsibility for providing ratings.

Facility Ratings include Normal Ratings[4] and Emergency Ratings[5] for the following Facilities[6] identified in Section 2 of this document:

1. Transmission Line Facilities

2. Transformer Facilities

3. Series and Shunt Compensation Facilities

a. Shunt Capacitor Facilities

b. Shunt Reactor Facilities, and

c. Series Reactor Facilities

The Facilities addressed in this document are comprised of various electrical equipment or Elements[7]. FPL Facilities may contain one or more Elements. For example, a Transmission Line Facility includes conductors, line traps, switches, breakers, protective relays, etc. Section 3 of this document includes the methodology for rating the major equipment of the Facility. Major equipment is the element of a Facility that is unique to that type of facility. Major equipment includes the following:

1. Transmission Cables/Conductors

2. Transformers (Autotransformers and Generator Step-Up Transformers (GSU))

3. Reactors (series and shunt applications)

4. Capacitors (shunt only)

Section 4 of this document includes that methodology for rating the elements of a Facility that are common to several facilities. These elements also referred to as Terminal Equipment or Associated Equipment, include:

1. Substation Conductors

2. Breakers

3. Instrument Transformers

4. Switches

5. Circuit Switchers

6. Line Traps (also known as Wave Traps), and

7. Relay Protective Devices

Note that FPL has no transmission level Series Capacitors, Flexible A/C Transmission Systems such as SVC or STATCOM, High Voltage Direct Current or Electrical Energy Storage devices.

The Facility Rating Methodology in this document holds to the principle that the Facility Rating shall equal the most limiting applicable Equipment Rating[8] of the individual equipment that comprises that Facility. For the purposes of this Facility Rating Methodology the equipment rating is the Normal and Emergency “thermal” Rating of the equipment. The “thermal” rating is the amount of loading or output that the equipment can support at 60HZ, typically measured in amps or MVA.

FPL designs equipment to operate within the ranges of voltage, frequency, fault current and transient conditions for which it is intended to function. This consideration of operating limitations is applicable to all equipment on the BES. For considerations unique to the specific equipment, refer to Sections 3 and 4.

For temporary Facility Ratings, FPL follows the same methodology as described herein.

The assigned rating may deviate from the Facility Rating Methodology set forth herein where appropriate to do so based on unique circumstances of a specific Facility or configuration of Facilities.

2. Bulk Electric System Facilities

2.1 Transmission Line Facilities

Transmission Line Facilities are comprised of four main sets of equipment: (1) transmission substation terminal equipment; (2) distribution substation high-side terminal equipment; (3) transmission line conductors and (4) relay protective devices. Line conductors may be underground cable or overhead conductors. The transmission line terminal equipment includes breakers, switches, line traps, substation conductors and instrument transformers. Switches and substation conductors also comprise distribution substation high-side equipment.

Generally, the design intent for Transmission Line Facilities is to provide a Normal Rating (continuous) and three Emergency Ratings: 100% continuous, 110% for 7 minutes, 120% for 7 minutes and 130% for 5 minutes. The Normal Rating is determined by identifying the most limiting applicable equipment associated with the Facility while operating at the rated current and under the other conditions specified below. The Emergency Rating is established by calculating the maximum allowable pre-existing current such that the Facility can be operated at the following overload conditions: 110% for 7 minutes, 120% for 7 minutes or 130% for 5 minutes. Each Facility is individually evaluated and rated based on the limiting applicable equipment rating. In some cases, an allowable pre-existing current level greater than zero can not be established. For these cases, the Emergency Rating equals the Normal Rating.

In some cases the limiting element for a line may change with various switching arrangements. For example, where a transmission line is terminated with two breakers in parallel, the Facility Rating may be reduced when one of the breakers is open and the remaining breaker or other associated equipment has an ampacity lower than the established Facility Rating when both breakers are closed. Such situations are identified and handled in the FPL System Control Center with specific Energy Management System (EMS) alarm logic.

For the purpose of this document an autotransformer in series with a transmission line is treated as a separate Facility with its own ratings.

2.2 Transformer Facilities

A Transformer Facility includes a Generator Step-Up (GSU) transformer or autotransformer and associated equipment. Associated equipment connected to the transformer typically includes breakers, buswork, switches and relay protective devices.

Each Transformer Facility is individually evaluated and rated based on the limiting applicable equipment rating.

GSU Transformer Facilities have Normal and Emergency Ratings that equal the Normal Rating.

In some cases the limiting element for a Transformer Facility may change with various switching arrangements. For example, where a transformer is terminated with two breakers in parallel, the Facility Rating may be reduced when one of the breakers is open and the remaining breaker or other associated equipment has an ampacity lower than the established Facility Rating with both breakers closed. Such situations are identified and handled in the FPL System Control Center with specific EMS alarm logic.

2.3 Series and Shunt Compensation Facilities

FPL utilizes Series and Shunt Compensation Facilities. Shunt Compensation devices include Reactor and Capacitor Facilities. Series Compensation devices include only Reactor Facilities. FPL does not currently use series capacitors, Flexible A/C Transmission Systems such as SVC or STATCOM, High Voltage Direct Current or Electrical Energy Storage devices.

Series and Shunt Compensation Facilities are comprised of: a reactor or capacitor and associated equipment. Associated equipment typically includes breakers, switches, substation conductors, instrument transformers and relay protective devices.

Compensation Facilities are individually evaluated and rated based on the limiting applicable equipment rating.

In applications where a Compensation Facility is in series with a Facility whose Emergency Rating is equal to the Normal Rating, the Compensation Facility Emergency Rating may be set equal to the Normal Rating. An example is a reactor in series with a shunt capacitor. The Shunt Capacitor Facility Emergency Rating equals the Normal Rating; therefore, the Reactor Facility Emergency Rating may be set equal to its Normal Rating.

3. Major Equipment Ratings

3.1 Underground Transmission Cable

Introduction

Normal and Emergency Ratings for underground transmission cables are determined using the rating methodologies described below.

Design Criteria/Industry Standards

• AEIC CS2 – 1997 - Specifications for Paper and Laminated Paper Polypropylene Insulated Cable

• AEIC CS7 – 1993 - Specifications for Crosslinked Polyethylene Insulated Shielded Power Cables Rated 69 Through 138kV

• IEC60287 2nd Edition – 1982 – Calculation of the Continuous Current Ratings of Cables (100% Load Factor)

Rating Methodology

FPL uses two common algorithms for calculating the Normal Rating.

The FPL preferred method is the Neher-McGrath method outlined in "The Calculation of Temperature Rise and Load Capability of Cable Systems," in AIEE Transactions on Power Apparatus and Systems, vol. 76, October 1957.

An alternate and equally acceptable method is that outlined in the European IEC standard, "Calculation of the Continuous Current Ratings of Cables, (100% Load Factor), Publication 287, 2nd Edition, 1982.

Considerations

The FPL inputs to the underground rating methodologies are as follows:

1. Earth Ambient Temperature: Normally assumed to be 30 degrees Celsius per Table 5-2 in the EPRI Underground Transmission Systems Reference Book (1992 Edition, p. 209). A different value may be used depending on field conditions.

2. Soil Thermal Resistivity: Measured at various locations along the route of a new underground line. Typically measurements are made and soil samples are collected at intervals of 1000 ft at the depth the cable(s) is to be placed

3. Soil Moisture Content: Measured at the same locations as the soil thermal resistivity.

4. Load Factor of Proposed Underground Line: Normally based on the projected loading of the proposed line. The minimum load factor used is 75%. The maximum load factor used is 100%.

5. Cable Depth: To be based on proposed route profile, local code restrictions and locations of existing sub surface utilities.

6. Fault Current: Obtained from a system fault study for each proposed installation.

7. Adjacent Heat Sources: Type (i.e.: adjacent heat pipes, distribution lines, or transmission lines) and location are obtained through field surveys of the proposed route of a new line.

8. Cable Characteristics: The cable's characteristics (conductor size, type, stranding, bonding method, insulation thickness, etc.) are used to determine the cables thermal and electric losses.

9. Cable Maximum Operating Temperature: The maximum allowable cable temperature as specified in the following industry standards:

AEIC CS2-1997 - Specifications for Paper and Laminated Paper Polypropylene Insulated Cable

AEIC CS7 - 1993 – Specifications for Crosslinked Polyethylene Insulated Shielded Power Cables Rated 69 through 138kV

Normal and Emergency Ratings (Manufacturer/Industry Standard/Custom)

Normal and Emergency Ratings for Underground Transmission Cable are not provided by the manufacturer. The ratings are determined by FPL based upon this methodology.

The Normal Rating of underground transmission conductors at FPL is based on the steady state current carrying capacity of the conductor. It is a continuous thermal rating based on a maximum rated conductor temperature.

The Emergency Rating of underground transmission conductors at FPL is a short term thermal rating based on an assumed fixed overload and time period. The rating represents the maximum load current that can be applied to a cable operating at the specified initial conditions for the fixed time period without causing thermal damage to the cable.

3.2 Overhead Transmission Conductors

Introduction

Normal and Emergency Ratings for overhead transmission conductors are determined using the rating methodology and assumptions described below.

Design Criteria/Industry Standards

• Alcoa Conductor Engineering Handbook, Section 6, Current-Temperature Characteristics of Aluminum Conductors, copyright 1959.

• IEEE Standard 738 –1993 - IEEE Standard for Calculating the Current-Temperature Relationship of Bare Overhead Conductors

Rating Methodology

Bare overhead transmission conductor ratings at FPL are consistent with and use the methodology described in the Alcoa Conductor Engineering Handbook, Section 6, “Current-Temperature Characteristics of Aluminum Conductors”, copyright 1959 and the IEEE Standard for Calculating the Current-Temperature Relationship of Bare Overhead Conductors (IEEE Standard 738 –1993).

Considerations

Summarized below are the FPL inputs used in the methodology described in the Alcoa Conductor Engineering Handbook, Section 6, “Current-Temperature Characteristics of Aluminum Conductors”, copyright 1959 and the IEEE Standard for Calculating the Current-Temperature Relationship of Bare Overhead Conductors (IEEE Standard 738 –1993).

1. Maximum Operating Temperature: The maximum temperature of the bare overhead conductor when it is carrying normal rated current under the assumed parameters.

2. Ambient Air Temperature: The assumed temperature of the air surrounding the bare overhead conductor.

3. Conductivity: The conductivity of the base material used to make the conductor. The conductivity is used to calculate the resistance of the conductor.

4. Emissivity: The ratio (without units) comparing the emissive power of the bare overhead conductor to the emissive power of a black body.

5. Absorbtivity: The ratio (without units) comparing the heat absorbing properties of the bare overhead conductor with that of an ideal absorber.

6. Wind Speed Normal to Conductor: The velocity of the wind blowing in a direction perpendicular to the path of the bare overhead conductor.

7. Solar Insolation: The total heat flux from the sun received by a surface normal to the sun’s rays at sea level.

The assumed values used for these inputs are shown in the following tables.

1. Assumptions for rating ACSR overhead transmission conductors

|Version |Prior to 1978 |1978-1993 |1994-2006 |After 2006 |

|Maximum Operating Temperature (oC) |75 |100 |100 |115 |

|Ambient Temperature (oC) |25 |35 |35 |35 |

|Conductivity (% IACS)* |62 |61 |63 |62 |

|Emissivity |0.5 |0.5 |0.9 |0.9 |

|Absorbtivity |0.47 |0.47 |0.9 |0.9 |

|Wind speed normal to conductor (mph) |1.364 |2 |3 |2 |

|Solar insolation (W/ft2) |93 |93 |93 |93 |

* International Annealed Copper Standard

2. Assumptions for rating AAAC overhead transmission conductors

|Version |Prior to 1994 |1994-2006 |After 2006 |

|Maximum Operating Temperature (oC) |75 |75 |85 |

|Ambient Temperature (oC) |25 |35 |35 |

|Conductivity (% IACS)* |52.5 |54 |53 |

|Emissivity |0.5 |0.9 |0.9 |

|Absorbtivity |0.47 |0.9 |0.9 |

|Wind speed normal to conductor (mph) |1.364 |3 |2 |

|Solar insolation (W/ft2) |93 |93 |93 |

* International Annealed Copper Standard

3. Assumptions for rating AAC overhead transmission conductors

|Version |Prior to 1994 |1994-2006 |After 2006 |

|Maximum Operating Temperature (oC) |75 |75 |85 |

|Ambient Temperature (oC) |25 |35 |35 |

|Conductivity (% IACS)* |62 |63 |62 |

|Emissivity |0.5 |0.9 |0.9 |

|Absorbtivity |0.47 |0.9 |0.9 |

|Wind speed normal to conductor (mph) |1.364 |3 |2 |

|Solar insolation (W/ft2) |93 |93 |93 |

* International Annealed Copper Standard

4. Assumptions for rating copper overhead transmission conductors

|Version | 2/0 and Smaller |Conductors larger than 2/0 |Conductors larger than 2/0| Conductors larger than|

| |Conductors |Prior to 1994 |1994-2006 |2/0 After 2006 |

|Maximum Operating Temperature (oC) |75 |100 |100 |115 |

|Ambient Temperature (oC) |25 |25 |35 |35 |

|Conductivity (% IACS)* |97.5 |97.5 |98.5 |97.5 |

|Emissivity |0.5 |.5 |.9 |0.9 |

|Absorbtivity |0.47 |.47 |.9 |0.9 |

|Wind speed normal to conductor (mph) |1.364 |1.364 |3 |2 |

|Solar insolation (W/ft2) |93 |93 |93 |93 |

* International Annealed Copper Standard

Normal and Emergency Ratings (Manufacturer/Industry Standard/Custom)

Normal and Emergency Ratings for bare overhead conductor are not provided by the manufacturer. The ratings are determined by FPL based upon this methodology.

The Normal Rating of bare overhead conductors at FPL is based on the steady state load current carrying capacity of the conductor. It is a continuous thermal rating based on a maximum rated conductor temperature.

The Emergency Rating of bare overhead conductors at FPL is based on a conductor’s response to a step change in the steady state load current applied to the conductor. It is a short term thermal rating based on a calculated maximum initial load current and an assumed fixed overload and time period. The rating represents the maximum final load current that can be applied to a conductor operating at the initial load current for the fixed time period without exceeding the conductor’s maximum rated operating temperature. The Emergency Rating is expressed as a percentage of the Normal Rating.

The typical Emergency Ratings are:

• 110% of Normal Rating for 7 minutes

• 120% of Normal Rating for 7 minutes

• 130% of Normal Rating for 5 minutes

Other Emergency Ratings for overhead transmission conductors may be calculated on a case by case basis, for specific conditions which may require a different percentage of Normal Rating and/or fixed time period

3.3 Autotransformers

Introduction

Transmission system autotransformers on the BES are rated on an individual basis. Generally, the autotransformers have a Normal and two Emergency Ratings: summer and winter Emergency Ratings. The Emergency Ratings are developed from typical daily load and temperature profiles provided to the manufacturer as part of the procurement specification.

Design Criteria/Industry Standards

• ANSI/IEEE 57.91-1995 (R2004), Guide for Loading Mineral-Oil-Immersed Transformers

Rating Methodology

FPL uses manufacturer rating for normal and emergency conditions when available.

Where manufacturer ratings are not available, FPL uses the “PT-Load” computer program developed by Electric Power Research Institute (EPRI). This program utilizes the algorithms in the above IEEE standard.

In general, other transformer equipment such as bushings or tap changers should not limit auto transformer ratings. However, should the rating of other transformer equipment be less than the transformer, the transformer rating will equal the most limiting equipment rating.

Considerations

The following criteria are currently used as the design basis to specify autotransformer Emergency Rating capability. The transformer shall be capable of being loaded beyond its nameplate rating with less than 1% loss- of-life, as calculated using the formula in ANSI/IEEE C57.91, over the 24-hour load and temperature profiles in the procurement specification. Generally, the summer peak loading capability is 1.3 per-unit for 6 hours and the winter peak loading capability is 1.5 per-unit for 3 hours. Per-unit loading is defined for these purposes as the multiple of the transformer's nameplate rated MVA output with all equipped pumps and fans operating.

The assumptions for the Normal Rating are:

• Ambient temperature shall not exceed 40 degrees C and the average temperature of the cooling air for any 24hr period shall not exceed 30 degrees C

• The top liquid temperature of the transformer shall not be lower that -20 degrees C.

• Altitude shall not exceed 3300 ft

• Supply voltage and load current are approximately sinusoidal

The limiting assumptions under either summer or winter overloads are as follows:

• Cumulative loss-of-life shall not exceed 1% over the 24-hour period.

• Top oil temperature shall not exceed 110°C during the 24-hour period.

• Winding hottest-spot temperature shall not exceed 140°C during the 24-hour period.

• Temperature of any metallic part not in contact with paper insulation shall not exceed 150°C during the 24-hour period. Metallic parts in contact with paper insulation shall not exceed 120°C

• Free gas or dissolved acetylene shall not be generated during the 24-hour period.

• The summer ratings are calculated using the ambient temperature cycle between 25°C and 35°C.

• The winter ratings are calculated using the ambient temperature cycle between 2°C and 15°C.

• Bushing nameplate rating (if limiting)

• Tap Changer nameplate rating (if limiting)

Normal and Emergency Ratings (Manufacturer/Industry Standard/Custom)

The Normal and Emergency Ratings for an auto transformer are provided by the manufacturer. In cases, where a manufacturer rating is not available, FPL calculates the ratings as described above.

3.4 Generator Step-Up Transformers (GSU’s)

Introduction

Transmission GSU’s are specified, designed and applied for the full range of system loading conditions and ranges to which they will be subjected. The Normal Rating for FPL transmission GSU’s are rated per the manufacturer’s nameplate. FPL does not have ratings above the Normal Rating for GSU’s therefore the Emergency Ratings are equal to the Normal Ratings.

Design Criteria/Industry Standards

• ANSI/IEEE 57.91-1995 (R2004), Guide for Loading Mineral-Oil-Immersed Transformers,

Rating Methodology

Rating algorithms are used by the manufacturer to establish the Normal and Emergency Ratings. These algorithms are based on ANSI/IEEE 57.91.

Considerations

The assumptions for the ratings are:

• Ambient temperature shall not exceed 40 degrees C and the average temperature of the cooling air for any 24hr period shall not exceed 30 degrees C

• The top liquid temperature of the transformer shall not be lower that -20 degrees C.

• Altitude shall not exceed 3300 ft

• Supply voltage and load current are approximately sinusoidal

Normal and Emergency Ratings (Manufacturer/Industry Standard/Custom)

Normal Ratings for the GSU are provided by the manufacturer. The Emergency Rating is equal to the Normal Rating.

3.5 Shunt Capacitors

Introduction

Shunt capacitors, in support of the BES, are specified, designed, and applied for the full range of system voltage conditions and ranges to which they will be subjected. Capacitors are static devices with fixed loading based on operating voltage.

Other associated terminal equipment connected to the capacitors such as breakers, switches, substation conductors and relay protective devices are generally designed not to be limiting elements for the operation of the capacitor. Therefore, the capacitor is generally the limiting element of the Facility. However, should the rating of other equipment be less than the capacitor, the Facility Rating will equal the most limiting equipment rating.

Design Criteria/Industry Standards

• IEEE 18 - 2002, IEEE Standard for Shunt Power Capacitors

• IEEE 1036 - 1992, IEEE Guide for the Application of Shunt Power Capacitors

Rating Methodology

Shunt capacitor ratings are developed and provided by the manufacturer.

Considerations

The assumptions for the ratings are:

• The minimum ambient temperature is -40°C.

• The average ambient temperature for any 24 h period does not exceed 40°C.

• The altitude does not exceed 1800 m above sea level.

Normal and Emergency Ratings (Manufacturer/Industry Standard/Custom)

The Normal Rating for FPL shunt capacitors are provided by the manufacturer. As applied on the FPL system, shunt capacitor Emergency Ratings are equal to the Normal Ratings.

3.6 Shunt Reactors

Introduction

Shunt reactors are specified, designed, and applied for the full range of system voltage conditions and ranges to which they will be subjected. Shunt reactors are static devices with fixed loading based on operating voltage.

Other associated equipment connected to the reactor such as breakers, switches, substation conductors and relay protective devices are generally designed not to be limiting elements for the operation of the Facility. Therefore the shunt reactor rating is usually the limiting element of the Facility. However, should the rating of other equipment be less than the reactor, the Facility Rating will equal the most limiting equipment rating.

Design Criteria/Industry Standards

• IEEE C57.21-1990, IEEE Standard Requirements, Terminology, and Test Code for Shunt Reactors Rated Over 500 kVA

Rating Methodology

Shunt reactor ratings are developed and provided by the manufacturer.

Considerations

The assumptions/considerations for the ratings are:

• The ambient temperature does not exceed 40°C, and the average temperature of the cooling air for any 24 h period does not exceed 30°C.

• The altitude does not exceed 1000 m (3300 ft.).

• Under operation, the top liquid temperature of an oil-immersed shunt reactor is no lower than minus 20°C.

Normal and Emergency Ratings (Manufacturer/Industry Standard/Custom)

The Normal Rating for FPL shunt reactors is provided by the manufacturer. As applied on the FPL system, shunt reactor Emergency Ratings are equal to the Normal Ratings.

3.7 Series Capacitors

FPL has no transmission level series capacitors.

3.8 Series Reactors

Introduction

FPL currently uses series reactors in series with lines, autotransformers, bus sections, and capacitor banks. These reactors are designed to control power flow and /or limit fault currents or capacitor discharge currents. The series reactor is typically designed to be the most limiting element of its Facility. However, should the rating of other equipment be less than the reactor, the Facility Rating will equal the most limiting equipment rating.

Design Criteria/Industry Standards

• ANSI/IEEE C57.16-1996, IEEE Standard Requirements, Terminology, and Test Code for Dry-Type Air-Core Series-Connected Reactors

• ANSI C57.99-1958, Guide for Loading Dry-Type and Oil-Immersed Current-Limiting Reactors

Rating Methodology

Series reactor ratings are developed and provided by the manufacturer.

Considerations

The assumptions/considerations for the ratings are:

• The ambient temperature does not exceed 40°C, and the average temperature of the cooling air for any 24 h period does not exceed 30°C.

• The altitude does not exceed 1000 m (3300 ft.).

Normal and Emergency Ratings (Manufacturer/Industry Standard/Custom)

The Normal and Emergency Ratings for FPL series reactors are provided by the manufacturer.

4. Terminal Equipment and Relay Protective Device Ratings

4.1 Substation Conductors

Introduction

Normal and Emergency Ratings for substation conductors are determined using the rating assumptions and methodology described below.

Design Criteria/Industry Standards

Ampacities for rigid bus are taken directly from the Standard Ampacity Tables of IEEE Guide for Design of Substation Rigid-Bus Structures, IEEE Standard 605-1998.

Bare overhead transmission conductor ratings at FPL are consistent with and use the methodology described in the Alcoa Conductor Engineering Handbook, Section 6, Current-Temperature Characteristics of Aluminum Conductors, copyright 1959 and the IEEE Standard for Calculating the Current-Temperature Relationship of Bare Overhead Conductors, IEEE Standard 738 –1993.

Rating Methodology

Rating algorithms used by IEEE for calculating the IEEE Standard Ampacity Tables used by FPL for rigid bus are shown in IEEE Guide for Design of Substation Rigid-Bus Structures, IEEE Standard 605-1998.

Rating algorithms used for calculating flexible transmission conductor ratings are shown in the Alcoa Conductor Engineering Handbook, Section 6, “Current-Temperature Characteristics of Aluminum Conductors”, copyright 1959 and the IEEE Standard for Calculating the Current-Temperature Relationship of Bare Overhead Conductors, IEEE Standard 738 –1993.

Considerations

Rigid Bus: Ratings are not provided by the manufacturers. Ampacities for rigid bus are taken directly from the Standard Ampacity Tables of IEEE Guide for Design of Substation Rigid-Bus Structures, IEEE Standard 605-1998, Annex B. The assumptions and their basis used to derive the IEEE tables are covered in pages 49 through 70 of the Standard in Annex C. The assumptions apply to both indoor and outdoor facilities. The basic assumptions are 40ºC ambient temperature, with sun, wind velocity of 2 ft/sec, emissivity factors of 0.5 for aluminum and 0.35 for copper. No other operating limitations apply.

Flexible Conductors: Ratings are not provided by the manufacturers. Ampacities for flexible bare conductors used in substations are based on single conductors in free air, with sun, emissivity factor of 0.5 and 40º C ambient temperature for Normal and Summer Emergency and 20º C ambient temperature for Winter Emergency. The wind velocity used for most conductors is 2 ft/sec. The wind velocity used for ACSR conductors used for installations of outdoor transmission substations is 2 mi/hr. No other operating limitations apply.

By design it is assumed substation conductors will not limit static load devices such as shunt compensators since their load is fixed and does not change during operation.

It is generally assumed substation conductors will not limit transmission line facilities by design and based on the following assumptions:

• The conductor in the pull-off tower down to the bus is rated under the same methodology as the transmission line overhead conductors.

• The current at the bus within the substation bay will split due to the parallel configuration

• Within the substation bay, conductor sag is not a concern

However should the substation conductor rating be less than other equipment ratings the most limiting rating will become the Facility Rating.

Normal and Emergency Ratings (Manufacturer/Industry Standard/Custom)

Normal and Emergency Ratings for substation conductors are not provided by the manufacturer. The ratings are determined by FPL based upon this methodology.

The Normal Ratings of substation conductors at FPL are established based on a maximum conductor temperature of 90º C with the assumptions stated above.

For application with autotransformers a six hour summer Emergency Rating and three hour winter Emergency Rating are established based on a maximum conductor temperature of 110º C with the assumptions stated above.

For application with transmission lines a short time Emergency Rating equal to 130% of the Normal Rating is established for substation conductors for up to 7 minutes based on the assumption and methodology provided above.

4.2 Circuit Breakers

Introduction

AC High Voltage Circuit Breakers on the FPL BES are specified by operating voltage, continuous current, interrupting current and operating time in accordance with ANSI/IEEE Standard C37 series. ANSI/IEEE specifically addresses Circuit Breaker current loading in IEEE Standard C37.010-1999 section 5.4. This Standard is used as a guide in establishing continuous and emergency load current capabilities.

Design Criteria/Industry Standards

The following standards are referenced in the breaker specifications and address thermal rating:

• ANSI C37.04 - 1999, IEEE Standard Rating Structure

• ANSI/IEEE C37.010 - 1999, AC High-Voltage Circuit Breakers Rated on a Symmetrical Current Basis

Rating Methodology

General Continuous Load Current ratings are provided in IEEE C37.010-1999 Section 5.4.3.1

Allowable Continuous Load Current ratings based on Actual Ambient temperature are provided in IEEE C37.010- 1999 Section 5.4.3.2.

Allowable Short-Time Load Current ratings based on actual pre-current operation below its allowable continuous load current are provided in IEEE C37.010-1999, Section 5.4.3.3.

Allowable Emergency Load Current capability ratings are provided in IEEE C37.010-1999, Sections 5.4.4.1, 5.4.4.2, 5.4.4.3, and 5.4.4.4.

Under all conditions FPL internally determines its own inspection and maintenance policy following emergency load current operation. In special applications FPL may apply criterion different than those suggested by IEEE standard C37.010 based on Manufacturer recommendations and/or prudent internal engineering evaluation.

Considerations

The assumptions/considerations for the ratings are:

• 20°C ambient temperature- winter.

• 40°C ambient temperature- summer

• Temperature rise as function of the 1.8 power of the current (ANSI/IEEE C37.010, Section 4.4.3.2)

• Thermal Time Constant t = .5

• Temperature Rise and Total Temperature Limit of various circuit breaker components are based on 65°C rise plus ambient

• Accelerated deterioration limit of some circuit breaker parts under emergency conditions

• Pre-contingency loading of (100%).

Normal and Emergency Ratings (Manufacturer/Industry Standard/Custom)

1. Normal Ratings are provided by the manufacturer but may be modified pursuant to IEEEC37.010-1999 as described below

Continuous Load Current:

Outdoor Transmission Circuit Breakers are designed for normal application where sustained load current does not exceed the rated continuous current at an altitude above sea level of 1000m (3300 ft), or less, and an ambient temperature that does not exceed 40 deg C. -IEEE C37.010-1999 Section 5.4.3.1

Allowable Continuous Load Current:

When the actual applied ambient temperature is other than 40 deg C a conversion factor can be applied to determine the actual allowable continuous load current. -IEEE C37.010- 1999 Section 5.4.3.2

Short Time Continuous Load Current:

Standard breaker design provides for 40 deg C ambient temperature, 65 deg C rise limit and 105 deg C maximum temperature limit. When a circuit breaker has been operating at a current level below its allowable continuous load current it is possible to increase the load current for a short time to a value greater than the allowable current without exceeding the permissible temperature limitations. The length of time that the short-time load current can be carried depends on these factors: - IEEE C37.010-1999, Section 5.4.3.3.

- The magnitude of short time current to be carried

- The magnitude of initial current carried prior to the application of the short time current

- The thermal-time characteristics of the circuit breaker

- Typical design time constant t = 0.5 hr

- Typical design exponential temperature increases as 1.8 power as the current increases

2. Emergency Ratings are not provided by the manufacturer. They are calculated based on the methodology herein.

Emergency Load Current Carrying Capability:

During emergency periods, operation may be required at higher load currents than permitted by the ambient compensation procedures. Limits of the total temperature for the circuit breaker will be exceeded under the specified emergency which may cause reduced operating life of the circuit breaker: - IEEE C37.010-1999, Sections 5.4.4.1, 5.4.4.2, 5.4.4.3, and 5.4.4.4

Under all conditions FPL internally determines its own inspection and maintenance policy following emergency load current operation. In special applications FPL may apply criterion different than those suggested by IEEE standard C37.010 based on Manufacturer recommendations and/or prudent internal engineering evaluation. The IEEE standard is used as a Guide specific FPL criterion may differ in special cases.

4.3 Instrument Transformers

4.3.1 Current Transformers

Introduction

Current transformers (CTs) may be supplied in the form of bushing CTs, slip-over CTs, or free-standing CTs for transmission facilities. Combined Metering Units (MUs), contain internal CTs along with an internal potential voltage transformer (PT or VT).

Design Criteria/Industry Standards

• IEEE-C57.13-2008 - Standard Requirements for Instrument Transformers

Rating Methodology

CT and MU ratings are developed and provided by the Manufacturer. These ratings typically include thermal rating factors and overload factors.

Considerations

Overload ratings are assumed to start from full load from the point of the Rating Factor, less any derating for ambient temperature as defined in IEEE-C57.13 - 2008.

The assumptions/considerations for the ratings are:

• Elevation is less than 1000m

• For air cooled CTs the 24hr ambient temperature is less than 30°C and the maximum temperature is less than 40°C

• Alternately CTs may be rated with the 24hr ambient temperature is less than 55°C and the maximum temperature is less than 65°C

Normal and Emergency Ratings

The Normal and Emergency Ratings for CTs and Metering Units are provided by the manufacturer.

4.3.2 Voltage Transformers

Introduction

Protection and metering devices are supplied voltages from potential transformers (PTs or VTs), coupling capacitor voltage transformers (CCVTs), or combined metering units (MUs, addressed above). PTs and CCVTs, in support of the BES, are specified, designed, and applied for the full range of system conditions to which they will be subjected and are static devices with fixed loading based on operating voltage.

Design Criteria/Industry Standards

• The requirements for PTs/VTs are defined by IEEE-C57.13-2008 - Standard Requirements for Instrument Transformers

• The standard for Coupling Capacitor Voltage Transformers (CCVTs) is ANSI C93.1.-1999 - Requirements for Power-Line Carrier Coupling Capacitors and Coupling Capacitor Voltage Transformers (CCVT)

Rating Methodology

PT and CCVT ratings are developed and provided by the Manufacturer.

Considerations

The assumptions/considerations for the ratings are:

• Elevation is less than 1000m

Normal and Emergency Ratings (Manufacturer/Industry Standard/Custom)

The Normal Ratings for PTs and CCVTs are provided by the manufacturer. The Emergency Rating is equal to the Normal Rating.

4.4 Air Disconnect Switches

Introduction

FPL utilized the industry standards referenced below as guidelines in creating this Facility Rating Methodology. Specifically applicable to this Facility Rating Methodology is the ACCC (Allowable Continuous Current Class) designation of the industry standards. As stated in IEEE C37.30-1997: “The ACCC designation of an air switch is a code that identifies the composite curve relating the loadability factor, LF, of the switch to the ambient temperature, ΘA, as determined by the limiting switch part class designations.”

An ACCC of AO1 is used for air disconnect switches that were designed in accordance with ANSI C37.30-1962 and earlier standards, for which there was not an ACCC designation. The most common air disconnect switches manufactured in accordance with the ANSI/IEEE C37.30 standards after the 1962 revision, up to the date of the current revision of this Facility Rating methodology, have an ACCC of DO6. An ACCC designation of DO6 is the composite of the DO4 and FO6 switch part class designations. There are two different switch parts that are given a switch part class designation of FO6 in IEEE C37.30-1997. These switch parts are: (a) silver, silver alloy, or equivalent contacts in air, and (b) silver, silver alloy, or equivalent conducting mechanical joints. Although both are given an FO6 designation, these two switch parts have a different allowable maximum temperature, ΘA, and a different limit of observable temperature rise at rated current, Θr.

Design Criteria/Industry Standards

• IEEE C37.30-1997, IEEE Standard Requirements for High-Voltage Switches

• ANSI C37.32-1996, High-Voltage Air Disconnect Switches Interrupter Switches, Fault Initiating Switches, Grounding Switches, Bus Supports and Accessories Control Voltage Ranges–Schedules of Preferred Ratings, Construction Guidelines and Specifications

• IEEE C37.37-1996, IEEE Loading Guide for AC High-Voltage Air Switches (in Excess of 1000V)

Rating Methodology

In developing the Normal Ratings (allowable continuous current) for air disconnect switches; FPL utilizes the equation provided in section 5.4.1 of IEEE Std C37.30-1997.

In developing the Emergency Ratings for air disconnect switches; FPL utilizes the guidelines provided in section 6.2 of IEEE Std C37.37-1996.

Considerations

Air disconnect switches on the FPL transmission system have ACCC designations of either AO1 or DO6. Unless a specific switch nameplate rating and ACCC designation is verified, FPL assumes worst case, and adopts the lowest resulting rating according to this Facility Rating Methodology.

To allow for the creation of simplified guidelines, ambient temperatures are defined as 20 degrees-C for winter, and 40 degrees-C for summer. For actual ambient temperatures above -10 degrees-C, up to and including 20 degrees-C, the winter rating will be used. For actual temperatures above 20 degrees-C, up to and including 40 degrees-C, the summer rating will be used. Temperatures outside of the -10 degrees-C to 40 degrees-C window are not expected within FPL Utility’s service territory.

Per IEEE C37.37-1996, the guidelines for Emergency Ratings within this Facility Rating methodology assume that “the allowable maximum temperatures of the switch parts were not exceeded during the 2 hours prior to an emergency.” Therefore, it is assumed that the pre-contingency loading of the switches is 100% of the Normal Rating.

Normal and Emergency Ratings (Manufacturer/Industry Standard/Custom)

1. Normal Ratings

Within this document, FPL considers the Normal Rating to be synonymous with the “allowable continuous current” rating of the industry standards referenced above. The Normal Rating for FPL transmission air disconnect switches is provided by the manufacturer (i.e., rated continuous current on the nameplate).

Depending on ambient temperature, the allowable continuous current rating may actually be above the rated continuous current. FPL rates its air disconnect switches on a worst case scenario basis. For Normal Ratings at 40 degrees-C, that would be an air disconnect switch with an AO1 designation, which provides an allowable continuous current equal to the rated continuous current. For this case, the loadability factor is 1.00.

If a specific air disconnect switch nameplate rating and ACCC designation is verified, then a higher allowable continuous current rating for that air disconnect switch can be developed.

2. Emergency Ratings

Emergency Ratings for switches are not provided by the manufacturer. They are calculated based on the methodology herein.

To determine the Emergency Rating, the loadability factor is multiplied by the rated continuous current of the air disconnect switch (nameplate value).

When calculating the emergency loadability factor for all air disconnect switches, the equations in section 6.2 of IEEE 37.37 – 1996, are used to calculate all four values applicable to FPL switches: (1) AO1, (2) DO4, (3) FO6 for contacts in air, and (4) FO6 for conducting mechanical joints, and the lowest resulting loadability factor is selected. This will ensure safe utilization of Emergency Ratings, regardless of whether the switch has an ACCC of AO1 or DO6.

For specific cases where the air disconnect switch nameplate rating and ACCC designation is verified, it is allowable to use the loadability factor associated with that ACCC designation, rather than the overall worst case scenario.

4.5 Circuit Switchers

Introduction

Circuit Switchers on the FPL BES are given current ratings based on the manufacturer’s recommendations, which are based on industry standards. Circuit Switchers are not manufactured in accordance with industry breaker standards; however the load current ratings are based on the industry breaker standard listed below.

Design Criteria/Industry Standards

• ANSI/IEEE C37.010 - 1999, IEEE Application Guide for AC High-Voltage Circuit-Breakers Rated on a Symmetrical Current Basis.

Rating Methodology

Allowable continuous load current ratings are based on section 5.4.3.2 of IEEE C37.010- 1999.

Allowable short-time load current ratings are based on section 5.4.3.3 of IEEE C37.010-1999.

Allowable emergency load current capability ratings are based on in IEEE C37.010-1999, Section 5.4.4.

Considerations

To allow for the creation of simplified guidelines, ambient temperatures are defined as 20 degrees-C for winter, and 40 degrees-C for summer. For actual ambient temperatures above -10 degrees-C, up to and including 20 degrees-C, the winter rating will be used. For actual temperatures above 20 degrees-C, up to and including 40 degrees-C, the summer rating will be used. Temperatures outside of the -10 degrees-C to 40 degrees-C window are not expected within FPL Utility’s service territory.

The calculations in ANSI/IEEE C37.010 allow for ratings to be based on the loading prior to the short-time loading. FPL assumes the pre-loading to be 100% of the rated continuous current.

Temperature rise limit of various circuit switcher components is 65°C (149°F).

The switcher is at an altitude above sea level of 1000m (3300 ft), or less.

Normal and Emergency Ratings (Manufacturer/Industry Standard/Custom)

1. Normal Ratings are provided by the manufacturer but may be modified pursuant to IEEEC37.010-1999 as described below.

Rated Load Current:

The equipment is designed for normal application where sustained load current does not exceed the rated continuous current at an altitude above sea level of 1000m (3300 ft), or less, and an ambient temperature that does not exceed 40 deg C. See IEEE C37.010-1999 Section 5.4.3.1

Allowable Continuous Load Current:

When the actual applied ambient temperature is other than 40 deg C a conversion factor can be applied to determine the actual allowable continuous load current. See IEEE C37.010- 1999 Section 5.4.3.2

Short Time Continuous Load Current:

Standard equipment design provides for 40 deg C ambient temperature, 65 deg C rise limit and 105 deg C maximum temperature limit. When a circuit switcher has been operating at a current level below its allowable continuous load current, it is possible to increase the load current for a short time to a value greater than the allowable current without exceeding the permissible temperature limitations. The length of time that the short-time load current can be carried depends on these factors: (See IEEE C37.010-1999, Section 5.4.3.3.)

- The magnitude of short time current to be carried

- The magnitude of initial current carried prior to the application of the short time current

- The thermal-time characteristics of the circuit breaker

- Typical design time constant t = 0.5 hr

- Typical design exponential temperature increases as 1.8 power as the current increases

2. Emergency Ratings are not provided by the manufacturer. They are calculated based on the methodology below.

Emergency Load Current Carrying Capability:

During emergency periods, operation may be required at higher load currents than permitted by the ambient compensation procedures. Limits of the total temperature for the circuit switcher will be exceeded under the specified emergency which may cause reduced operating life of the circuit switcher: - IEEE C37.010-1999, Section 5.4.4.

Under all conditions FPL internally determines its own inspection and maintenance policy following emergency load current operation. In special applications FPL may apply criterion different than those suggested by IEEE standard C37.010 based on manufacturer recommendations and/or prudent internal engineering evaluation. The IEEE standard is used as a guide. Specific FPL criterion may differ in special cases.

4.6 Line Traps

Introduction

Line Traps, sometimes referred to as wavetraps, are series connected devices usually in one or more phases of the high voltage power system. These are used in conjunction with the power line carrier system to block relay carrier such that the carrier signal is forced or trapped to all go into the coupling capacitor where it is routed into the power line carrier transmitter/receiver. The current carrying element consists of a large coil plus a tuning pack and internal arrestor, rated for a given ampacity. The line trap is generally used at the ends of a transmission line; however, there are other applications where it may be used in conjunction with capacitor banks or power transformers to block the carrier signals from getting lost into the “remote” devices so that the carrier signal only goes down the transmission line.

Design Criteria/Industry Standards

• ANSI C93.3-1995, Standard Requirements for Powerline Carrier Line Traps.

Rating Methodology

Line trap ratings are developed and provided by the manufacturer.

Considerations

The assumptions/considerations for the ratings are:

• Ambient temperature is - 40°C to + 45°C

• Altitude is less than 1000m

• Any values of currents in excess of the rated current in this standard may cause the designed temperature rise to be exceeded and may shorten the life expectancy of the line trap.

Normal and Emergency Ratings (Manufacturer/Industry Standard/Custom)

The Normal Rating for line traps are provided by the manufacturer. The Emergency Rating for line traps are provided in ANSI C93.3 - 1995.

4.7 Relay Protective Devices

Introduction

For the purpose of this document relay protective devices will be defined by the term “Relay” from IEEE C37.90-2005. “A relay is an electric device designed to respond to input conditions in a prescribed manner and, after specified conditions are met, to cause contact operation or similar abrupt change in associated electric control circuits.”

Relay protective devices are not directly connected to high voltage equipment but are connected indirectly through instrument transformers.

Relay Protective Devices (Relays) have evolved from the electromechanical to the solid state to the microprocessor protection packages. The ratings of these devices typically do not limit the transmission facilities. However, should the rating of the relay protective device be less than other equipment in the Facility, the Facility Rating will equal the most limiting equipment rating.

Design Criteria/Industry Standards

• IEEE C37.90-2005 - Standard for Relays and Relay Systems Associated with Electric Power Apparatus

Rating Methodology

Relay ratings are developed and provided by the Manufacturer.

Considerations

Relay protective devices are specified, designed and applied for the full range of expected system conditions to which they will be subjected through the instrument transformers.

The assumptions/considerations for the ratings are:

• Elevation is less than 1500m

• Ambient temperature and humidity as specified for application

Normal and Emergency Ratings (Manufacturer/Industry Standard/Custom)

The Normal and Emergency Ratings for relay protective devices are provided by the manufacturer.

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[1] Glossary of Terms Used in Reliability Standards, February 12, 2008. Facility Rating – The maximum or minimum voltage, current, frequency, or real or reactive power flow through a facility that does not violate the applicable equipment rating of any equipment comprising the facility.

[2] FPL has a separate Rating Methodology Document for Generation.

[3] Standard FAC-008-1 – Facility Ratings Methodology: Adopted by Board of Trustees February 7, 2006, Effective date of August 7,2007

[4] Glossary of Terms Used in Reliability Standards, February 12, 2008. Normal Rating – The rating as defined by the equipment owner that specifies the level of electrical loading, usually expressed in megawatts (MW) or other appropriate units that a system, facility, or element can support or withstand through the daily demand cycles without loss of equipment life.

[5] Glossary of Terms Used in Reliability Standards, February 12, 2008. Emergency Rating – The rating as defined by the equipment owner that specifies the level of electrical loading or output, usually expressed in megawatts (MW) or Mvar or other appropriate units, that a system, facility or element can support, produce, or withstand for a finite period. The rating assumes acceptable loss of equipment life or other physical or safety limitations for the equipment involved.

[6] Glossary of Terms Used in Reliability Standards, February 12, 2008. Facilit[pic][7]y – A set of electrical equipment that operates as a single Bulk Electrical System Element (e.g., a line, a generator, a shunt compensator, transformer, etc.)-

[8] Glossary of Terms Used in Reliability Standards, February 12, 2008. Element - Any electrical device with terminals that may be connected to other electrical devices such as a generator, transformer, circuit breaker, bus section, or transmission line. An element may be comprised of one or more components.

[9] Glossary of Terms Used in Reliability Standards. Equipment Rating – The maximum or minimum voltage, current, frequency, real and reactive power flows on individual equipment under steady state, short circuit and transient conditions, as permitted or assigned by the equipment owner.

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