Communications Interoperability



Communications Interoperability

Device

Power Test Document

Version 1.4

Senior Design II 2006

Lafayette College

Table of Contents

1 Overview 3

2 Low Voltage Alarm Test 4

2.1 Setup 4

2.2 Method 4

2.3 Results 4

3 Backup Battery, Battery Charger, and LV Alarm Integration Test 5

3.1 Setup 5

3.2 Method 5

3.3 Results 6

4 Crossover from External AC to Backup Battery Test 6

4.1 Setup 6

4.2 Method 6

4.3 Results 6

5 Distribution Board – Without Load Test 6

5.1 Setup 6

5.2 Method 6

5.3 Results 7

6 Distribution Board – With Load Test 7

6.1 Setup 7

6.2 Method 7

6.3 Results 7

7 Test vs. Functionality and Requirements 9

Table of Figures

Figure 1 – Low Voltage Alarm Test Setup 4

Figure 2 – Low Voltage Alarm Test Results 4

Figure 3 – Backup Battery, Battery Charger, and LV Alarm Setup 5

Figure 4 – Distribution Board without Load Test Results 7

Figure 5 – Test Amperage vs. Expected System Amperage 8

Figure 6 – Converter Efficiency 8

Figure 7 – Ripple Effects on System Voltage Levels 8

Figure 8 – Testing vs. Functionality and Requirements Matrix 9

Overview

This document contains a description of the test performed to test the power subsystem of the CID. The POWER block distributes power to each block of the system. The Communications Interoperability Device plugs into a 120 VAC outlet. The POWER block charges the battery while the system is receiving 120 VAC. If the 120 VAC should fail, a battery backup powers the system for as long as possible. An alarm will be set if the battery is almost discharged. The POWER block trips the system if it detects an overcurrent. We will test each functional subblock in our POWER block: BACKUP BATTERY, VOLTAGE CONVERSION, and PROTECTION SYSTEM.

Tests Performed

• Low Voltage Alarm (R002, R009)

• Backup Battery, Battery Charger, and LV Alarm Integration (R006, R007, R011)

• Crossover from External AC to Backup Battery (R006)

• Distribution Board – Without Load (R006, R010)

• Distribution Board – With Load (R006, R010)

Tests NOT Performed

• Protection System – We assume the fuses and circuit breakers in our design work correctly. A fuse will be permanently damaged by testing. Circuit breaker testing degrades the part’s performance and may impair future operation of the breaker.

Low Voltage Alarm Test

1 Setup

[pic]

Figure 1 – Low Voltage Alarm Test Setup

The low voltage alarm circuitry was connected to a typical lab bench power supply. A digital multimeter was connected to the low voltage alarm output.

2 Method

The voltage range from 9 VDC to 15 VDC was applied at the input. The output of the low voltage alarm was recorded. We expected the alarm to be high at 11.5 VDC and lower.

We also tested the low voltage alarm with a voltage divider attached. The voltage divider is necessary to decrease the alarm voltage from 3.8 V to 3.3 V.

3 Results

The results for the testing are shown in Figure 2. All tests were successful

|Input Voltage |LV Alarm |LV Alarm with |

|(V) | |Voltage Divider |

| | |(V) |

|14 Volts. Fully charging the backup battery took a few hours. The bus bar was measured to be at 14.2 V. All voltages were found to be accurate.

Crossover from External AC to Backup Battery Test

1 Setup

This part of the system will be setup from backup battery, battery charger, and LV alarm test.

2 Method

The battery charger will be connected to an external 120 VAC. The external power will be removed from the system by switching the power supply (battery charger) off. The Communication Interoperability Device should remain powered via the backup battery.

3 Results

The power supply (also known as the battery charger) and the back up battery are connected in parallel. When the power supply was flipped off, the system did not lose power. The FPGA did not reset. All power was transferred with zero crossover time.

Distribution Board – Without Load Test

1 Setup

The power distribution board was connected to a lab bench power supply at 13.8 VDC. 13.8 V is the charging voltage from the battery charger. According to material specifications, the DC to DC converters will work in the 9 to 18 V range. The 13.8 VDC was connected to the distribution board input connector.

2 Method

A digital multimeter was used to check the input and output voltages at the backplane connector. The backplane connector is a great test point because this is where all signals will be entering and leaving the board.

3 Results

The results for the testing are shown in Figure 4.

|At Connector |Correct |

| |Voltage? |

|12 VDC in |yes |

|5 VDC out |yes |

|5 VDC out |yes |

|3.3 VDC out |yes |

Figure 4 – Distribution Board without Load Test Results

The spot checks of the inputs and outputs were taken with a multimeter. Each voltage level was correct.

Distribution Board – With Load Test

1 Setup

We connected the distribution board to a lab bench power supply at 13.8 VDC. A 4 Ohm 20 W resistor was placed on each DC to DC converter to draw a large amount of current.

2 Method

The 4 Ohm 20 W resistor drew a large amount of power from the DC to DC converter. The amount of power used in testing is more than the expected maximum value during real time operation of the Communication Interoperability Device. We determined how much power was being dissipated over the 20 W resistors. This would verify that our power distribution board can handle up and above our expected system load.

The load was left connected to the DC to DC converters for a long period of time. Ripple effect is an adverse effect of the AC to DC rectifier within the BATTERY CHARGER causing the output voltage to dip up and down. Any ripple effect in the output voltages was analyzed.

3 Results

The amount of current used in our testing exceeded the expected amount of current that our system will pull. We assumed all eight communication interface boards were in use. We also assumed that all chips were pulling their maximum current at the same time. In reality, this is unlikely to happen and chip power usage will be more diversified. The test load is much larger than what we ever expect our system load to be. The percent difference between the test load and expected load can be seen in Figure 5.

|Supply VDC |Power Max W |Max Current A|Expected System|Test Load A |% of Expected |

| | | |Load | | |

|5 |15 |3 |0.3 |1.25 |416.67% |

|5 |10 |2 |0.91 |1.25 |137.36% |

|3.3 |5 |1.52 |0.2 |0.825 |412.50% |

Figure 5 – Test Amperage vs. Expected System Amperage

The input and output currents and voltages to and out of the DC to DC converters were measured. Power is equal to the product of current and voltage. Using the ratio of the power input and power output, the efficiency of each converter is found. The converter specification sheets are close to the efficiencies measured in lab.

|DC DC Converter Input |DC DC Converter Output |Calc. |Data Sheet |

| | |Efficiency |Efficiency |

|V |I |W |

|5 |15 |Small, but noticeable |

|5 |15 |insignificant |

|3.3 |15 |insignificant |

Figure 7 – Ripple Effects on System Voltage Levels

Test vs. Functionality and Requirements

The following table maps the above Tests to the Functions created to meet the requirements, and then maps the tests to those exact requirements.

[pic]

Figure 8 – Testing vs. Functionality and Requirements Matrix

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