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REGION 6
CONTROL PANEL SELECTION GUIDE
FOR SMALL WATER AND WASTEWATER SYSTEMS
TABLE OF CONTENTS
Introduction Page 1
Chapter Page
I Mandatory Regional Standards 3
II Recommended Basic Control Components 4
III Optional Electrical Control Compnents 7
IV Examples of Commonly Used Systems 13
INTRODUCTION
This guide was developed to assist project managers, system designers, and maintenance personnel in the design and selection of electrical control panels and components that are safe, functional, and cost effective to construct and maintain.
The guide is only useful in determining the control needs of the facilities designed. The facility itself is the result of many considerations including ROS class, setting, customer desires, terrain, water, power, sanitation needs, etc. The facility design criteria needs to be completed long before the control panel discussions take place. Except in extreme circumstances, the design criteria is established during the "feasibility study" of a proposed project which takes place a year ahead of the "design" phase and two years preceding "construction". Do no let the tail wag the dog. The controls should meet the needs of the facility, rather than the other way around.
The guide should be used to facilitate discussions between the design engineer and the project manager concerning design criteria for the panel. Though the mandatory components assure required protection of personnel, the project manager and designer assume responsibility for selecting the additional components needed for additional safety and/or reliability. Design concerns such as life expectancy of the system, level of required maintenance, operating costs, consequences of system failure, and customer service all need to be incorporated into the analysis criteria. It boils down to risk management. The project manager (Rec. Staff, Ranger, etc.) must determine the acceptable risk for reliability, personnel safety, vandal resistance, etc., and either convey that accurately to the designer or stay involved with the project to its conclusion. The results of this analysis should be documented in the design prospectus and the engineering report.
The sections that describe controls available for use are divided into four chapters:
I. Mandatory Regional standards for electrical controls.
II. Recommended basic control components
III. Optional electrical control components.
IV. Examples of commonly used systems
Chapter I provides the mandatory R-6 standards for electrical control that all designs must incorporate into systems. These standards were developed to assure that all legal requirements are met on all installations in the Region. Because of their significance to health, safety, and design function these standards cannot be compromised.
Chapter II outlines recommended basic electrical control panel components that include the mandatory standards plus selected features and design criteria that experience has shown will make the control panel safer, more effective, and more efficient for the average situation. These added features will provide better protection to critical machinery and greatly enhance basic trouble shooting. Therefore, project managers are encouraged to incorporate these recommended components into their system controls.
These components are available individually and as integrated systems, from many sources, including field wired combinations, premanufactured assemblies, and custom designed/factory built assemblies typified by traditional standardized Regional Office designs. The systems could be combinations of standardized parts (desirable for interchangeability) and premanufactured components. Procurement could be through a consolidated Regional contract, contractor design/construct, FS design/contractor furnish, or other combinations. See Chapter IV for illustrative examples.
Chapter III presents a representative array of the optional electrical control components available. This section provides a variety of features that can be incorporated into a panel to deal with project requirements determined by site-specific considerations. In choosing which options to incorporate into the basic panel, the project manager and designer should consider the need and costs of the additional options. Some considerations are size of the system, remoteness of the facility, need for fire (or other) response, environmental concerns should the system fail, and local maintenance expertise. Optional controls need to be selected during the design phase of a project so that correct panel size and configuration are obtained.
Chapter IV provides the designer and local managers examples of commonly used systems. Examples include: pre-manufactured, sealed systems (black boxes); field assembled kits from "off the shelf" components (commonly employed for simple operations or contractor-provided controls); and custom designed, factory built, electro-mechanical systems (commonly used in the Region since 1975 in over 400 control panels). The Regional panel employs 4 standard plug-in relays to perform the majority of the control functions. All the starters, relays, push buttons, indicator lights, selector switches, running time meters, and operation counters are of the same manufacturer. This allows standardization and interchange as well as simplifying operation and maintenance.
Limitations of the Guide
This guide does not adequately discuss the design and options for large complex control systems. The type of controls needed for complicated systems like water or wastewater treatment plants are unique to each installation. The Regional Office should be contacted for design assistance on these projects. The selected options for system and resource protection must directly relate to site specific conditions, proximity to service and monitoring, funds available and potential risks. The project manager must consider each of these variables and, through the use of a decision matrix or other tool, provide the designer and Regional Office Facilities Group with the required criteria.
This guide does not address the Forest Service design/review/approval delegation of authority. Designers are cautioned to follow current procedures.
I. Mandatory Regional Standards for Electrical Controls
The following standards are required for the safety of personnel and to minimally protect the equipment and facilities. All electrical control and alarm systems must meet the requirements of:
National Electrical Code (NEC),
Underwriter's Laboratory (UL) (applicable to each component part),
Underwriter's Laboratory (UL) 508 Industrial Control Standard (Does
not apply to field built units.),
American Society of Mechanical Engineers (ASME),
Uniform Plumbing Code (UPC),
Uniform Fire Code (UFC),
Forest Service Health & Safety Code,
and all other nationally recognized codes and pertinent local codes. Provide GFCI protection on all line voltage control circuits. The use of low voltage control circuits wherever feasible is strongly urged for personnel safety.
In addition, all electrical control and alarm systems must include a complete electrical schematic diagram showing the overall system, physical wiring diagram, and parts list for each component. This is necessary for trouble shooting, procurement of replacement parts or modifications in the future. A plumbing schematic, including valves, sensors, regulators, pumps, backflow preventers, storage facilities, etc. is indispensable for the same reasons.
Pre-manufactured, sealed systems (black box) and field assembled kits from "off-the-shelf" components must satisfy the above requirements.
The designer is cautioned that these codes were never intended to be design manuals. The primary function of electrical controls is to safely operate the connected equipment. Secondary functions such as adequate protection of investments, reliability, maintenance, and trouble shooting are not likely to be accomplished by minimally meeting codes. The sole function of the electrical code is to protect people and property from damage due to shock and overheating. Codes do not require, for instance, the interchangeability of parts, a desirable feature if a component fails. The recommendations in the next section of this Guide address these problems.
II. Recommended Basic Control Components
The components described in this section are highly recommended for use in most panels because they not only meet the mandatory requirements of I, above, but they provide improved reliability, trouble shooting capability, and ease of operation. The primary function of these basic components is to control operation, and to provide the secondary functions of safety, monitoring, and alarms. A discussion is presented for each component, explaining what it does and what risk is being diminished or eliminated. When selecting components, consider using standardized parts to enhance interchangeability of parts.
Enclosure Installed Cost $ (varies)
The control enclosure(s) are NEMA-rated metal or plastic box(s) designed to contain the system components. They satisfy NEC and UL requirements for isolating electrically live or moving parts from personnel. They also afford mechanical protection from physical damage.
Typical ratings are:
- NEMA 1 - mechanical protection only
- NEMA 3R - protection from rain
- NEMA 4 - protection from water spray
- NEMA 4X - corrosion resistance
- NEMA 12 - dust and moisture protection
NOTE: UL 508 REQUIRES DOOR INTERLOCKS ON ALL FACTORY BUILT PANELS. INTERLOCKS ARE OPTIONAL FOR FIELD BUILT PANELS. See "Door Interlock" under "Optional Components."
Hand-Off-Auto Selector Switches Installed Cost $XXX
Three-position Hand-Off-Auto selector switches are used for each motor. The HAND position allows the motor to be turned ON continually with no automatic shutdown for testing or emergency operation. OFF position stops the motor, overriding all other pilot devices; this allows work to be done on the pump motor, or the use of only one pump of a duplex pump station. AUTO position allows the motor to run when the pilot devices (float or pressure switches, etc.) call for the motor to run.
Motor Circuit Protectors (MCP's) Installed Cost $XXX
MCP's are specially designed quick trip circuit breakers for motor short-circuit protection.
Motor Starters Installed Cost $XXX
Motor starters with thermal overload relays provide overload protection for all motors. This prevents failure of the motor from overheating should the motor be worked harder than designed because of equipment failure. Motor starters turn motors on when activated by the pilot devices.
Low Voltage Circuitry (Cost is included with other devices.)
Control transformers and power supply are used to reduce incoming voltage to 24 VAC and 24 VDC for personnel safety.
24 volt AC relays and 24 volt DC relays are standard and readily available from suppliers. Only four types of relays need to be stocked.
24VAC and 24VDC systems are used for safety concerns to minimize shock hazards to people who may come in contact with the control circuits. Component prices are the same for 24VAC or 120VAC systems.
AC controls are not used over long distances because they have problems operating reliably over small gage wires. Typical problems are voltage drop and failure to de-energize due to the self-generating AC voltage. Consequently, the relay remains energized even though the sensing device is not sending any signal. Therefore, 24 volt DC relays are used for controls which have their pilot or sensing devices located long distances from the control panel or in hazardous areas.
Running Time Meter Installed Cost $XXX (used for each motor)
A running time meter totals the time of operation of each motor. It is useful for scheduling maintenance of the equipment. When used together with an operation counter, it can detect abnormal operation of motors starting and stopping excessively, thus causing overheating and wear. In a system where alternating motors are used, running time meters can indicate an unequal use, and therefore faulty mechanical equipment.
Operation Counter Installed Cost $XXX (used for each motor)
Operation counters advance one count for each motor start. This is the only indication of excessive motor on-off cycles which may be caused by improper setting of the setpoints or the malfunction of one of the control components. An unusually high number of operations on the counter may show that motor failure or deterioration was not caused by overloading, but by some other system failure.
Power-On Lights Installed Cost $XXX (each)
POWER-ON lights indicate when line voltage, 24VAC or 24VDC are present. This is the most rudimentary indication of an electrically live panel.
Single Phase Voltage Monitor Installed Cost $XXX
This device monitors the voltage supplied to the control panel and the motors. It provides protection for motors and circuits against overvoltage or undervoltage by shutting off the power. When the voltage returns to normal, the system automatically resets itself.
Three Phase Voltage Monitor Installed Cost $XXX
This device provides the same protection as the single phase monitor, but for a three phase system. It also protects against undervoltage between the phases or phase to ground, phase reversal, or loss of one phase. Loss of one of the phases may not be readily apparent without this device, but will ultimately cause motor burn-up.
Lightning Arresters Installed Cost $XXX per block of 4
Modern gas tube type arresters are recommended by the NEC for areas exposed to lightning. This includes virtually all areas encompassed by R6 National Forests. They allow voltage surges caused by lightning to bleed off to ground instead of destroying the control system components. The older type carbon arresters are still available but should be avoided as they cannot be reused and are not as reliable.
Additional options allow the user to monitor performance, document critical operations, facilitate trouble shooting, and maintain reliability of the system. The designer is encouraged to weigh the risks and include those components from the next section that are cost effective.
III. Optional Components
Each one of these individual device prices includes the relays, wiring, indicator lights, and test switches to control that device.
Door Interlock Installed Cost $XXX
The main disconnect door interlock disconnects all power to the panel when the door latch mechanism is rotated to unlock the door. This is a safety device that prevents access to energized parts within the panel by unknowledgeable people.
NOTE: UL REQUIRES DOOR INTERLOCKS ON FACTORY BUILT PANELS AND THOSE CONTAINING SERVICE ENTRANCE EQUIPMENT! A DISCONNECT IS REQUIRED IMMEDIATELY ADJACENT TO THE PANEL IF NOT CONTAINED IN THE PANEL.
Strip Heater Installed Cost $XXX
Thermostatically controlled strip heaters reduce condensation and eliminate component corrosion which could cause malfunctions. This is recommended practice when control panels are located in unheated, high humidity locations.
Service Entrance Installed Cost $XXX
Install circuit breakers for building lights, heat and outlets if required. The panel must be UL Service Entrance Rated if it is the sole service to the building. Otherwise, it must be sub-fed from a separate Service Entrance Rated panel, circuit breaker, or fused disconnect.
A separate power panel is saved where the control panel is used as the service entrance. This practice may be undesirable because all building power is interrupted when the panel is shut down.
Test Switches (Cost is included in related pilot device costs.)
Test switches enable simulation of system operation for each pilot device. They are installed for every sensor outside the panel to allow testing of the control panel functions without disconnecting any wiring or shorting any wiring. This allows a semi-skilled person to check all the panel functions without disconnecting line wiring and the possibility of replacing wiring in the wrong place. The typical system can be completely tested in 5-10 minutes with the test switches, allowing the operator to isolate the problem without test equipment.
Indicator Lights (Cost is included in related indicator or alarm function cost, unless otherwise noted.)
Indicator lights indicate which functions (motors, pumps, valves, etc.) are activated. Alarm lights indicate malfunction (breaker trip, motor overload, water level or pressure too high or too low, low flow, phase loss, general alarm, etc.) These lights are usually the quickest and easiest way to determine system condition and the cause(s) of a shutdown. Lock-in circuits are often included so the light has to be "cleared" manually. With this feature, a transient malfunction is much easier to detect.
Low-Level Alarm Installed Cost $XXX
This indicates that liquid is below some established critical level resulting from a malfunction or excessively high demand. It serves as a redundant shut-off on sewage pump station to keep water level above motor.
High-Level Alarm Installed Cost $XXX
This may indicate that the pump of a water system is on "HAND" or the control logic failed and let the tank flood. It also serves as a redundant shut-off to keep the tank from flooding due to control malfunction. In a wastewater pump station, it indicates the level is too high due to pump malfunction, control logic malfunction, or manual shut-off of the pumps.
Well Low-Level Alarm Installed Cost $XXX
This alarm indicates that the water level in the well has dropped below the "cutout probe" and was too low for the well pump to operate. This may be the reason why the pump is not running when the system calls for water. The "Well Pump Cutout/Restore" function is needed to energize this alarm. Wells are normally designed so the pumping rate is less than the well capacity. If this alarm activates, it may indicate that the demand has increased, groundwater level is dropping, flow into the well has decreased, or a flow control valve is not properly set. See "Well Pump Cutout/Restore Probes" above.
Well Low level protection Current Monitoring Devices Installed Cost $XXX
Patented "off-the-shelf" devices such as "Coyote" or "Sub-trol" (by Franklin Electric) monitor motors for over or under current. When water level drops below pump intake, blockage occurs in the piping, impellers erode, coupler splines shear, or for any other reason that water flow decreases or stops, an under current condition results and the monitor shuts the motor off for an adjustable pre-determined period. An over current condition resulting from a locked rotor, lowered pumping head, etc., will also cause the monitor to shut the motor off.
Low-Flow Alarm Installed Cost $XXX (used on clean water systems)
This alarm has a similar function to the well probes. The low-flow alarm consists of a flow switch in line with the pump discharge that monitors liquid flow. If the motor starts and does not produce flow within a pre-set time period, the pump is shut down. This alarm is manually reset if a low flow occurs. This will detect a no flow condition for the following causes:
a. Frozen line
b. Stuck check valve
c. Clogged intake
d. Discharge valve closed
e. Pump failure
Breaker Trip-Overload Alarm Installed Cost $XXX (used on any system)
The breaker trip overload alarm indicates that the motor circuit breaker has tripped or the motor overload relays have tripped. This alarm is used for any motor. The motor circuit breaker will trip on a short circuit fault. The motor overload relay will open when the motor is overloaded or when the voltage is reduced, causing the current to increase and overheat the motor windings. This will, in time, cause the motor to fail. Once the problem is corrected, these devices must be manually reset before the motor will run. The alarm will tell you that these protective devices are the reason the motor is not running. There could be other reasons that would keep the motor from running; no voltage, faulty motor, broken leads, broken or burned contact in the motor starter; but this alarm will not indicate these conditions.
Chlorine Low-Level Alarm Installed Cost $XXX (used on a water system with chlorine or other chemicals added)
This alarm indicates that the chlorine or other solution tank is almost empty. This alarm also shuts the well pump off. It is used to prevent untreated water from being pumped into the system.
Pump Seal Failure Alarm Installed Cost $XXX (used on submersible sewage pumps only)
This alarm detects leakage of moisture into the bearing housing of submersible sewage pump motor only. This moisture will cause corrosion and eventual failure of the motor. The alarm allows the opportunity to replace the seal before complete failure of the pump motor.
High and Low Pressure Alarms Installed Cost $XXX each (used on hydro- pneumatic tank water systems or sewage pumps)
These alarms indicate a sewage pump malfunction or that the pressure of a hydro-pneumatic tank is outside the designed operating limits. This could be caused by a malfunction of the pump, a logic malfunction in the panel, or leak in the system that the pump cannot overcome. High pressure alarms usually indicate blocked lines, failed pressure switches, or stuck valves. An additional pressure switch will have to be added to the system to operate one or both of these alarms. The alarm pressure switch works independently and serves as a backup sensor to the pump pressure switch. These alarms indicate either high or low pressure and shut the pump off. On duplex pump systems, high or low pressure will shut off the failed pump and start the alternate pump. Pumps which run against closed valves or blocked lines will overheat, destroy the seals, and damage the pump. Motor overloads will not detect a blocked line because the motor draws less current.
General Alarm Light Installed Cost $XXX
This alarm is an indicator light on panel with provision for hookup of external 24 VDC strobe light. This gives a visual alarm outside a building in which the panel is located. The general alarm light does not work in case of a power failure or tripped circuit breakers without battery backup. The general alarm will activate when any of the individual panel alarms engage. There are two other options that will give a warning that the system is down due to a power failure; (1) general alarm horn with a battery backup and DC power loss alarm, or (2) a phone dialer which has its own battery power. Descriptions of these follow.
Audible General Alarm Installed Cost $XXX
This audible alarm indicates that one of the alarms has been set off. A small alarm horn (sonalert) is placed on the control panel door and an external horn hookup is provided. The horns can be either 120VAC or 24VDC. The 120VAC system does not have emergency backup power supply, and is nonfunctional when power fails. The 24VDC system can have an emergency battery backup which will power the horns during a power failure, or if control system has a circuit breaker trip. The additional cost for the battery backup and alarm for loss of DC power is $XXX.
Phone Dialer Installed Cost $XXX
A recorded message is transmitted to up to five phones whenever the general alarm is activated. This assures that someone is alerted in a timely manner whenever the system is not functioning properly or a power outage occurs. A time clock can be added so that the dialer would not be activated during normal duty hours when personnel are available to monitor the alarm functions ($XXX). The message is repeated and the dialer continues to call until someone answers their phone and stops the dialer.
Operation and Maintenance Manual Estimated Cost $XXX
It includes operation instruction, troubleshooting guide, electrical diagrams, mechanical diagrams, functional descriptions, material list and suppliers and catalogue cutsheets for all the parts used. This manual details how the logic in the panel works, and how each relay functions. Anyone who is new to the system can become very familiar simply by reading the narrative and following the schematic and wiring diagrams. This manual's primary use is for troubleshooting any problem and locating the faulty part.
Spare Parts Cost $ (Varies)
Systems may be supplied with spare parts, relays, light bulbs, contacts, power supplies, etc. This cost is about 3%-5% of the panel price. If spare parts are not on hand, the downtime on a system could be 2-4 weeks. The spare parts are not always available locally and must be ordered from the manufacturer.
On-Site Testing $XXX (8 hrs. @ $XXX/hr.)
If project money is limited, rather than eliminate some equipment protective function, this optional cost of start-up by the control manufacturer should be eliminated.
The control panel manufacturer's representative and the Regional Office Electrical staff come to the site at completion of construction to assist the construction contractor in the initial start-up of the system. All circuits entering and leaving the control panel are tested to assure the integrity of the insulation of the conductors, and that all the circuits have been routed and connected correctly. The control panel is cycled through all its various functions to assure that no damage has been done during installation. Final field adjustments of the panel are performed to confirm proper system operation. The control panel manufacturer's representative conducts training for the local personnel who will be dealing with the control panel. The training will include normal, manual, and emergency operation covering the operation of the logic and how the switches affect the operation of the entire system. All the alarm functions are discussed along with the associated equipment failure or wrong switch position which could cause the alarm. There is no charge for Regional Office start-up assistance.
The control panel manufacturer's representative does the many adjustments and calibrations that have to be accomplished on larger, more complicated systems. The 1-year warranty on the panel begins at start-up of the system. Adjustments and calibrations usually must be made at that time. Should someone other than the control panel manufacturer's representative do this, and damage results to the control panel, the warranty may be voided.
ADDITIONAL CONSIDERATIONS
External Conductors Connected to Control Panels
Multiple pair, #22 AWG direct burial control cable (telephone cable) is used to transmit contact closures from sensing devices like float switches in water tanks to the control panel. The control cable is the smallest size manufactured. It is designed to be directly buried in a trench and to prevent water and mechanical damage to the conductors. The cable is double jacketed for protection from water damage, and double metal shielded to protect against mechanical or rodent damage. This is the same cable used by the telephone company, and it is made by many manufacturers.
#12 AWG, XLP-USE in conduit is used if all equipment is located in the same building. This is cross-linked polyethelene insulation that will not fail even if submersed in water.
Telephone cable is used because it is less expensive than individual conductors installed in conduit. Telephone cable for 12 pair, 22 AWG installed is about $XXX/ft., excluding trenching and backfilling. The cost of 8 #12 XLP-USE in 3/4" PVC conduit is about $XXX0/ft.
Splices
Splices are used primarily to correct damage caused by the contractor during installation. Continuous runs of cable up to 5,000 feet are available from the manufacturers. This enables installations to be made without using splices except for runs over 5,000 feet or where branch runs are joined together. The re-enterable splice kit specified is 1-1/2 feet long and is totally insulated to protect the cable pairs from corroding and failing ($XXX). To protect the splice kit from mechanical damage, and to provide access, the kit is normally placed in a concrete vault ($XXX) which is large enough to allow routing of the cable and working room for the person to do the splice. The concrete construction of the splice vaults is strong enough to be driven over with a vehicle without damaging the splice, and allows easy access to the splice through the removable metal cover of the vault. The splice kit and vault is typically specified to be furnished by the contractor at his expense to repair all installation faults. This discourages unnecessary splices due to contractor negligence. An optional above grade pedestal is available for above grade splices.
IV. Examples Of Commonly Used Systems
General Discussion
As discussed in the Introduction, the decision to install a "Standardized" control panel or a collection of "Black Box" components, depends on several considerations. The "Standardized" panel provides interchangeability of parts, individual component replaceability, familiarity of operation and maintenance, ease of trouble shooting, and telephone consultation with R.O. and S.O. Facility Engineers. Consequently, down time is minimized, repairs can economically be made by F.S. personnel, and since preventive maintenance is easier to accomplish, the system is less likely to break down unexpectedly.
The "Black Box" system may be as simple as the "Pressure Tank Water System" described below, a pre-manufactured integrated control system designed specifically for the particular application, or a complex assemblage of electronic controls that fills an entire control room. These systems typically have lower initial costs, are more quickly available, and are more familiar to non-industrial electricians and pump installers. These systems may be designed and installed by contractors; thus, code requirements, personnel safety (beyond code), and functionality are often overlooked. The Engineer should secure adequate review of plans by a qualified controls designer, ensure thorough review of submittals, and require construction (of the controls) by qualified individuals. The extreme complexity of code requirements for the control and safety of electrical equipment cannot be overstated. The typical Forest Service Civil Engineer is a "generalist" who cannot be expected to know and stay current with the specialized field of electrical controls and related code requirements.
The first two examples are described as "Black Box" control systems. The remaining examples are described as "Standardized" systems; however, the functions of the listed components are available in "Black Box" systems.
Specific Examples
Pressure Tank Water System $1,000 - Pump Control Box with Pressure Switch
This system pumps water from a well directly to a pressure tank as needed to maintain the desired system pressure. A pressure switch starts and stops the well pump by controlling the pump capacitor box provided for the pump. The system is deactivated and minimally protected by a circuit breaker. The components are individually mounted on the wall surface and connected by conductors in conduit.
This type of system would typically be used for a private single-family residence. Forest Service applications include a single comfort station with a drinking fountain, a guard station, and similar small developments. This example is included to illustrate the simplest pre-manufactured, field assembled electrical control system meeting minimum mandatory standards.
Surface Storage Tank with Duplex Booster Pumps to Pressure Tank
Refer to the flow schematic for this system. In this example, water is supplied from either a well or a packaged treatment plant and pumped to a ground level or buried storage tank. This system might be used in a campground where an elevated storage tank is infeasible due to flat terrain, and the water source (either well or treatment plant) produces a low flow that cannot meet instantaneous peak demand. However, by pumping to a storage tank, the maximum daily requirement can be met. Well flow is often determined by the aquifer rather than the designer's sizing of the pump, and standard sized treatment plants in the lower flow ranges are sometimes less expensive (than one sized for the peak flow), even with the storage tank included. In some cases, chlorine contact time requires a storage tank. The duplex booster pumps provide higher reliability and greater flow range flexibility than any single pump system, but a simplex booster pump could be used in lieu of the duplex where the risk of breakdown is more affordable than the cost of reliability.
The well pump or plant delivery pump, controlled by float switches in the tank, runs as necessary to maintain the water level for adequate storage. A chlorine pump can be included to automatically inject chlorine when the supply pump is running. Auxilliary contacts are available with most pump controllers to operate the chlorine pump simultaneously with the source pump. The duplex booster pumps, controlled by a pressure switch, run as necessary to maintain system pressure in the campground water piping. If chlorine contact time is a criteria, the low level alarm in the storage tank is set accordingly, and the booster pumps should shut down at that point. If that is not an issue, the pumps may be allowed to continue until the low flow switch shuts them off due to lack of output. A higher risk, lower cost option (compared with the flow switch) is PS 1. This is an optional set-point, available on most pump controlling pressure switches, which is typically set at 20 psi (minimum pressure required by Uniform Plumbing Code). If the pressure drops below 20 psi, the booster pumps cut out. To reset, the switch must be manually held closed until the pressure rises above 20 psi. The addition of a time delayed relay allows the flow switch (FS) cut out to be automatically interrogated as frequently as desired. The pressure switch cannot be automatically restarted, and it fails to protect the booster pumps against loss of water supply unless there is a simultaneous outflow through the system from the pressure tank.
A patented current monitoring device detects a drop in the running amperage of the well pump motor within seconds of drawdown below its intake. Several different brands are available. One could also be used to protect the packaged treatment plant source pump if it does not have a sensor (such as a flow switch or a low level float) to provide this function.
Selection of alarms and their annunciation (indicator light, flashing beacon, audible horn, telephone dialer, etc.) depends on availability of personnel to respond, proximity to residences (F.S., private, public, campers, etc.), type of power available (commercial utility or site generator), and the degree of risk that is acceptable to the facility operator or manager. Compliance with safety issues such as state mandated chlorine residuals is far more critical than the inconvenience of a closed shower building. Accordingly, the alarms and annunciations should be selected by the informed recreation project manager, after thorough consultation with the designers of both the water system and the control system.
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Surface Storage Tank with Duplex Booster Pumps to Pressure Tank
EXTENDED
COMPONENTS - INSTALLED COSTS QUANTITY UNIT PRICE PRICE
Combination Duplex Controller (Furnas - Class 83, 84, 86, 87, 88) $X,XXX
(Operates duplex booster pumps)
Voltage and phase monitor XXX
Selector switch - Hand-off-auto Duplex (2) XXX
Power-on indicator light AC XX
Low Voltage control transformer XXX
Lightning arrester (8) XXX
Power-on indicator light Low Voltage AC XX
Run timer meters -duplex booster pumps (2) XX
Operation counter -duplex booster pumps (2) XXX
Breaker/overload alarm indicator light XX
Simplex Pump Controller (Furnas - Class 83, 84, 86, 87, 88) X,XXX
(Operates well or treatment plant pump and chlorinator via auxilliary contacts)
Low Voltage control transformer XXX
Storage tank level switches OFF-ON (2) w/ related hardware XXX
Run time meter-well or treatment plant pump XX
Run timer meter-chlorinator XX
Operation counter-well or treatment plant pump XXX
Operation counter-chlorinator XXX
Chlorinator pump auxilliary contacts XX
NEMA 3 Enclosure containing field wired pilot devices & annunciation XXX
Chlorine low-level alarm XXX
Duplex pump low-flow alarm XXX
Storage tank high-level alarm XXX
Storage tank low-level alarm XXX
Pressure tank-high pressure alarm XXX
Current monitoring device (Coyote Mnft., Inc. or Franklin Electric) XXX
Chlorinator starter and motor circuit protector XXX
Chlorine low-level float switch XX
Storage tank low-level float switch XX
Storage tank high-level float switch XX
Pressure switch w/ low pressure cut out (Furnas, Square D) XXX
Pressure switch for high pressure alarm (Furnas, Square D) XXX
Flow switches (2) XXX
NEMA 7 junction box with lightning arresters on water tank 250
Spare parts 300
Operation and maintenance manuals 400
Options
General alarm horn 75
General alarm beacon with battery 75
Phone dialer (Radio Shack or Verbatim by RACO) 250 to 1,700
Most of the items listed indented below Furnas brand controllers are available as options and are listed in their Industrial Control Catalog No. 126. Operation counters and running time meters, though not listed in their catalog, are available by special request and will be custom mounted on the panel face in their fabrication shop. Many UL listed shops are also capable of producing a comparable panel with components as specified. This example is shown to illustrate yet another way to procure "code legal" control systems. A similar system has already been built with an R6 "standardized" control panel.
Well Pump to Tank Installed Cost $XXX - Basic Panel
Refer to the flow schematic for a water pump to tank water system. The system pumps water from a well to a storage tank. In automatic operation, a chlorine pump can be added to add chlorine to the water while the well pump motor is running. The well pump runs as necessary to maintain the water level in the storage tank and is controlled by float switches in the tank. Provision is made for well probes to automatically cut off the pump if the level in the well gets too low. Optional safety circuits are available to shut down the system (on AUTO) if the chlorine supply gets too low, or if the flow rate while the well pump is running is too low. High and low-level alarms can be provided on the water storage tank.
The basic panel consists of essential logic needed to operate the system in either the automatic or manual pumping mode. Overload and short circuit protection is incorporated for the motors and the electronic components. A strip heater is installed in the panel to keep the inside of the panel warm and the humidity low, and the panel is a NEMA 12 dust and oil tight construction. This keeps the terminals and components from corroding and failing. Two float switches in the storage tank deliver a signal to the relays in the control panel which energize the well pump starter. The panel uses 24 volt DC, and 24 volt AC relays to complete the logic and deliver the signal to the motor starter which delivers 240 volts to the well pump motor. In case of logic failure or an emergency, the logic can be over-ridden by use of a selector switch on the front of the panel, and the pump can be operated in manual. You still have the pump motor overload protection, but the level in the tank will have to be monitored visually or with a gage to determine when to manually shut off the pump. The approximate additive costs of optional alarms and indicators are listed following. Each option is described under the OPTIONAL COMPONENTS section.
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WELL PUMP TO TANK
EXTENDED
OPTIONS - INSTALLED COSTS QUANTITY UNIT PRICE PRICE
Basic panel $6,500
On-site testing 8 hrs. $ 65.00 520
Well low-level alarm 230
Well pump cutout/restore 100
Operation and maintenance manuals 400
Voltage monitoring relay 110
Power-on indicator light AC 30
Power-on indicator light DC 30
Run time meter-well pump 40
Run timer meter-chlorinator 40
Operation counter-well pump 100
Operation counter-chlorinator 100
General alarm horn 125
Battery backup-general alarm horn 140
General alarm light 145
Well pump DC power loss alarm 65
Breaker/overload alarm 90
Chlorinator pump breaker/overload alarm 90
Chlorine low-level alarm 133
Well pump low-flow alarm 203
Storage tank high-level alarm 238
Storage tank low-level alarm 238
Phone dialer 300-1,700
Chlorinator starter and motor circuit protector 260
Spare parts 300
Basic Operating Pilot Devices (Construction Costs Outside of Panel)
Installed
Cost
Well pump ON-OFF float switches: 2 floats, associated hardware $700
Nema 7 junction box with line protectors on water tank for control $250
cable for voltage surge protection cause by lighting strikes or
short circuits.
Associated Option Constructions Costs
Well probes (plus $.30/ft. per conductor) $125
Well pump low flow switch 75
Chlorine low-level float switch 80
Storage tank low-level float switch 80
Storage tank high-level float switch 80
General alarm horn 75
General alarm light 75
Chlorinator pump 300
Control panel installation 200
Hydro-Pneumatic Water System $4,600 - Basic Panel
Refer to the flow schematic for a hydro-pneumatic water system. The system pumps water from the well to a storage tank. The level in the storage tank is controlled by two well pump ON-OFF float switches with additional float switches for cutout-restore of the centrifugal pumps and two for tank high-low-level alarm. In automatic operation, a chlorine pump can be added to add chlorine to the water while the well pump is running. The well pump runs as needed to maintain the level in the storage tank. The storage tank water is pumped by a centrifugal pump into a hydro-pneumatic tank to maintain system pressure. The hydro-pneumatic tank is kept at the desired pressure by pressure switches that automatically start and stop the centrifugal pump. Optional safety switches are available to shut down the system; if the well gets too low, if chlorine supply gets too low, if there is insufficient water in the storage tank, if the pressure in the hydro-pneumatic tank is abnormally high, or if the flow from the pumps is stopped.
The basic panel consists of the same logic controls as the basic "Well Pump to Tank" panel, with addition for control of the centrifugal pump. The logic can also be over-ridden by use of a selector switch for the centrifugal pump. In HAND, the automatic shutoff capability is lost, and the pressure in the hydro-pneumatic must be monitored visually with a pressure gage to determine when to manually shut off the pump.
The optional alarms and indicators, and approximate additive cost are listed following. Each option is described under the OPTIONS section.
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HYDRO-PNEUMATIC PRESSURE WATER SYSTEM
EXTENDED
OPTIONS- INSTALLED COSTS QUANTITY UNIT PRICE PRICE
Basic panel $ 4,600
On-site testing 8 hrs. $65.00 520
Well low-level alarm 95
Operation and maintenance manuals 400
Voltage or phase monitoring relay 110
Power-on indicator lights 2 30.00 60
Run time meters 3 40.00 120
Operation counters 3 100.00 300
General alarm horn 125
Battery backup-general alarm horn 140
General alarm light 145
DC power loss alarm 65
Well pump breaker/overload alarm 90
Chlorinator pump breaker/overload alarm 90
Centrifugal pump breaker/overload alarm 90
Chlorine low-level alarm 133
Well pump low-flow alarm 203
Storage tank high-level alarm 200
Storage tank low-level alarm 133
Centrifugal pump low-flow alarm 203
Tank low-pressure alarm 133
Tank high-pressure alarm 133
Tank pressure gage 150
Phone dialer 1,700
Chlorinator starter & motor circuit protector 260
Spare parts 300
Basic Operating Pilot Devices (Construction Costs Outside of Panel)
Installed
Cost
Well pump ON-OFF float switches, 2 floats, associated hardware $ 700
Centrifugal pump restore float switch, 1 float, additional hardware 100
Centrifugal pump cutout float switch, 1 float, additional hardware 100
Centrifugal pump start/stop pressure switch 150
Associated Option Construction Costs
Well probes (plus $.30/ft. per conductor) $ 125
Well pump low-flow switch 75
Chlorine Low-Level float switch 80
Storage tank low-level float switch 80
Storage tank high-level float switch 80
Centrifugal pump low-flow switch 75
Tank low and high pressure switch, combined into one, 2-pole switch 155
General alarm horn 75
General alarm light 75
Chlorinator pump 350
Control panel installation 200
Hydro-Pneumatic Water System Without Storage Tank $3,400 - Basic Panel
Refer to the flow schematic for a hydro-pneumatic water system. This system pumps water from a well directly to a pressurized tank. In automatic operation, a chlorine pump can be added to add chlorine to the water while the pump is running. The well pump runs as needed to maintain the desired system pressure in the tank. The hydro-pneumatic tank is kept at the desired pressure by pressure switches that automatically start and stop the well pump. Optional safety switches are available to shut down the system; if the well gets too low, if the chlorine supply gets to low, if the pressure in the hydro-pneumatic tank is abnormally high, or if the flow from the well pump is stopped.
The basic panel consists of the same logic controls as the basic well pump to tank panel without the logic circuits and associated hardware for the float switches that would be in the storage tank. The well pump can be run in manual by use of a selector switch. The automatic shutoff capability is lost, and the pressure in the hydro-pneumatic tank must be monitored visually with a pressure gage to determine when to manually shut off the pump. The optional alarms and indicators, and approximate additive costs are following. The centrifugal pump options, or the storage tank options do not apply. Each option is described under the OPTIONS section.
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HYDRO-PNEUMATIC PRESSURE WATER SYSTEM
WITHOUT STORAGE TANK
EXTENDED
OPTIONS - INSTALLED COSTS QUANTITY UNIT PRICE PRICE
Basic panel $ 3,400
On-site testing 8 hrs. $ 65.00 520
Well low-level alarm 95
Operation and maintenance manuals 400
Voltage or phase monitoring relay 110
Power-on indicator lights 2 30.00 60
Run time meters 3 40.00 120
Operation counters 3 100.00 300
General alarm horn 125
Battery backup-general alarm horn 140
General alarm light 145
DC power loss alarm 65
Well pump breaker/overload alarm 90
Chlorinator pump breaker/overload alarm 90
Chlorine low-level alarm 133
Well pump low-flow alarm 203
Tank low-pressure alarm 133
Tank high-pressure alarm 133
Tank pressure gage 150
Phone dialer 1,700
Chlorinator starter & motor circuit protector 260
Spare parts 300
Basic Operating Pilot Devices (Construction Costs Outside of Panel)
Installed
Cost
Well pump start/stop pressure switch $ 150
Associated Option Construction Costs
Well probes (plus $.30/ft. per conductor) $ 125
Well pump low-flow switch 75
Chlorine low-level float switch 80
Tank low and high pressure switch, combined into one, 2-pole switch 155
General alarm horn 75
General alarm light 75
Chlorinator pump 350
Control panel installation 200
Duplex Wastewater Pump Station $4,975 - Basic Panel
Refer to the flow schematic for a duplex sewerage pump station. The system pumps sewage from a sump in response to level switches (float switches) in the sump. Submersible pumps #1 and #2 run as required to keep the level in the sump from getting too high. With relatively low flows into the sump, the pumps alternate running one at a time to keep the liquid between the "pumps off" level switch and the "pumps on" level switch. If the in-flow to the sump is too great to be handled by a single pump running, the second pump will come on when the level of the second pump level switch is reached. Low-level and high-level alarms are provided to indicate trouble in the system.
The basic panel consists of essential logic needed to operate the system in either the automatic or manual mode. Overload and short circuit protection is incorporated for the motors and the electronic components. A strip heater is installed in the panel to keep the inside of the panel warm and the humidity low, and the panel is a Nema 12 dust and oil tight construction. This keeps in the sump tank deliver a signal to the relays in the control panel which energizes the sump pump motor starters. The panel uses 24 volt DC and 24 volt AC relays to complete the logic and deliver the signal to the motor starters which turn on power to the sump pump motors. In case of logic failure or an emergency, the logic can be overridden by use of a selector switch on the front of the panel, and the pumps can be operated in HAND. You still have the pump motor overload protection, but the level in the sump tank will have to be monitored visually or with a gage to determine when to manually shut off the pumps.
The control panel will alternate the pumps as well as transfer to the other pump if the one being used fails and the system still calls for pumping. There is a third float switch in the tank which is above the primary ON float switch. Should the effluent continue to rise with one of the pumps operating and reach this third float switch, the second pump will be turned on simultaneously. Both will continue to pump until the level gets down to the OFF float switch. Both pumps can also be operated manually in case of emergency or logic failure.
Because a sewerage pump station is considered a hazardous area by State and National codes, the following four additive items are standard:
1.A low-level alarm to warn that the liquid is below the normal pump shutoff level float switch. This is a redundant shutoff to the OFF float. This could be caused by one of the pumps not shutting off, or a leak in the tank below the "pumps off" float switch. The pump motors are liquid cooled and should the effluent be below the pump intake and the pumps continue to run, the motors could burn out. This could lead to excessive heating or arcing which could ignite the flammable gases or liquid in the sump tank. This alarm is required if the pumps are not explosion-proof.
2. A high-level alarm to warn of imminent overflow of sewerage and contamination of the area due to pump failure, or clogged lines preventing the pumps from operating properly.
3. The control circuits are intrinsically safe. That is, the control relays limit the current so an explosion cannot occur if there are flammable liquids present in the wet well, and a spark occurs in the control circuits, or if a float switch cord should arc due to damaged insulation.
4. A pump breaker trip/overload alarm indicates that a pump will not operate due to electrical overload. This alarm allows you to fix a problem with a particular pump before you also have a problem with the other pump and have a completely inoperable system.
5. A general alarm light and horn mounted on the outside of the building visually and audibly warn of an alarm being displayed on the control panel. All the individual alarms trigger the general alarm. The other optional alarms and indicators, and approximate additive cost are listed following. The options are described under the OPTIONS section.
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DUPLEX WASTEWATER PUMP STATION
EXTENDED
OPTIONS - INSTALLED COSTS QUANTITY UNIT PRICE PRICE
Basic control panel $ 4,975
On-site testing 8 hrs. $ 65 520
Operation & maintenance manuals 400
Voltage monitor relay 110
Power on indicator light - AC 30
Power on indicator light - DC 30
Run time meter 2 40 80
Operation counter 2 100 200
Low-pressure alarm 133
High-pressure alarm 133
Battery backup-general alarm horn 140
DC power loss alarm 65
Pump motor thermal alarm 50
Pump seal failure alarm 238
Phone dialer 1,700
Spare parts 300
Basic Operating Pilot Devices (Construction Costs Outside of Panel)
Installed Cost
Pump ON-OFF float switches, 3 floats, associated hardware $ 900
High-level alarm, 1 float, additional hardware 100
Low-level alarm, 1 float, additional hardware 100
Nema 7 junction box with line protectors at sump for voltage 250
surge protection caused by lightning strikes or short circuits
External alarm light 75
External alarm horn 75
Associated Option Construction Costs
Low-pressure switch $ 70
High-pressure switch 70
Control panel installation 200
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