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Signal Power Distribution Inspection and Maintenance

Course 207 PARTICIPANT GUIDE PREVIEW O

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COURSE 207: INSPECTION AND MAINTENANCE OF SIGNALS POWER DISTRIBUTION

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TABLE OF CONTENTS PAGE How to Use the Participant Guide ........................................................................................... v

MODULE 1: SIGNAL POWER DISTRIBUTION INSPECTION AND MAINTENANCE

OVERVIEW .............................................................................................................................. 1

1-1 OVERVIEW ......................................................................................................................... 2

1-2 SAFETY ............................................................................................................................... 3

1-3 TOOLS AND MATERIALS .............................................................................................. 24

1-4 MAINTENANCE SCHEDULES ....................................................................................... 29

1-5 RECORD KEEPING .......................................................................................................... 30

1-6 SUMMARY........................................................................................................................ 31

MODULE 2: INSPECTION AND MAINTENANCE OF SIGNAL POWER

DISTRIBUTION ..................................................................................................................... 32

2-1 OVERVIEW ....................................................................................................................... 38

2-2 PRIMARY POWER FEED EQUIPMENT AND COMPONENTS .................................. 38

2-3 GENERAL POWER DISTRIBUTION EQUIPMENT AND COMPONENTS ................ 45

2-4 CIRCUIT EQUIPMENT AND PROTECTION................................................................. 73

2-5 OTHER: MOTOR GENERATOR SETS AND PHOTOVOLTAIC SYSTEMS .............. 81

2-5 SUMMARY........................................................................................................................ 86

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COURSE 207: INSPECTION AND MAINTENANCE OF SIGNALS POWER DISTRIBUTION

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LIST OF FIGURES Figure 1.1 Effects of Electrical Current on the Human Body, courtesy of OSHA ............................ 5 Figure 1.2 Arc Flash, courtesy of Fluke Corporation and OSHA ................................................... 10 Figure 1.3 Lockout/Tagout Equipment ............................................................................................ 14 Figure 1.4 Signals Power Distribution PPE.................................................................................... 16 Figure 1.5 Oscilloscope ................................................................................................................... 25 Figure 1.6 Oscilloscope ................................................................................................................... 25 Figure 1.7 Megohmmeter................................................................................................................. 26 Figure 1.8 Analog Multimeter ......................................................................................................... 26 Figure 1.9 Digital Multimeter.......................................................................................................... 26 Figure 1.10 DC Ground Detector for Continuous Monitoring ....................................................... 27 Figure 1.11 AC Ground Detector for Continuous Monitoring ........................................................ 27 Figure 1.12 Electrical Tape and Fuse Puller .................................................................................. 28 Figure 1.13 Cable Locator .............................................................................................................. 28 Figure 1.14 Resistance Made of Grounds Test Documentation Form ............................................ 30 Figure 1.15 Relay Case Battery Inspection Documentation Chart ................................................. 31 Figure 2.1 Main Power Feed Meter ................................................................................................ 39 Figure 2.2 Primary Power at the Automatic Transfer Panel .......................................................... 41 Figure 2.3 Timer Relay .................................................................................................................... 42 Figure 2.4 Transfer Switch .............................................................................................................. 43 Figure 2.5 Distribution Panel fed from Transfer Panel and Switch with Door Open..................... 44 Figure 2.6 Distribution Panel with Door Securely Closed.............................................................. 45 Figure 2.7 Distribution Panel with Door Open ............................................................................... 45 Figure 2.8 Intact and Secure Conduit.............................................................................................. 48 Figure 2.9 Wire going to Ground .................................................................................................... 49 Figure 2.10 Ground Rod .................................................................................................................. 50 Figure 2.11 Typical Signal Cable .................................................................................................... 54 Figure 2.12 Megger Insulated Resistance Test Documentation Form ............................................ 54 Figure 2.13 Junction Box at a Switch Machine ............................................................................... 60 Figure 2.14 Overhead Conduit and Cable Trays in a CIL .............................................................. 60 Figure 2.15 Main Disconnect Switch in the CIL ............................................................................. 61 Figure 2.16 Buss Bar ....................................................................................................................... 62 Figure 2.17 Ground Buss Bar .......................................................................................................... 62 Figure 2.18 Battery Bank and Rectifiers ......................................................................................... 64 Figure 2.19 Battery Plates, courtesy of SEPTA ............................................................................... 65 Figure 2.20 Battery Test .................................................................................................................. 65 Figure 2.21 Monthly Battery Inspection and Checklist ................................................................... 67 Figure 2.22 Battery Buss Voltage .................................................................................................... 68 Figure 2.23 Battery Rectifier Clear of Debris ................................................................................. 68 Figure 2.24 Battery Rectifier Charge Rate ...................................................................................... 68 Figure 2.25 Isolation Transformer .................................................................................................. 69 Figure 2.26 Hot Caps ...................................................................................................................... 70 Figure 2.27 Power Off Relay ........................................................................................................... 71 Figure 2.28 Electrical Schematic for Power Off Relay ................................................................... 71 Figure 2.29 Frequency Converter ................................................................................................... 72 Figure 2.30 Circuit Breakers ........................................................................................................... 74

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COURSE 207: SIGNAL POWER DISTRIBUTION INSPECTION & MAINTENANCE MODULE 1: Maintenance & Inspection Overview

DRAFT Intended For Use by Signals Training Consortium Members Only ©Transportation Learning Center Page 1

Module 1 SIGNAL POWER DISTRIBTUION

INSPECTION & MAINTENANCE OVERVIEW Outline

1-1 Overview1-2 Safety1-3 Tools1-4 Record Keeling1-5 General Schedules1-6 Summary

Purpose and Objectives

The purpose of this module is to provide the participant with an overview for maintenance and inspection of signal power distribution inspection and maintenance.

Following the completion of this module, the participant should be able to complete the exercises with an accuracy of 70% or greater: • Describe safety practices as related to performing inspection & maintenance for signal power

distribution.• Identify and explain the use of tools signal power distribution inspection and maintenance.• Identify agency specific schedules for signal power distribution inspection and maintenance.• Describe inspection and maintenance documentation for reporting as per agency regulations.

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Figure 1.2 Arc Flash, courtesy of Fluke Corporation and OSHA

Hazards associated with arc blasts include burns, wave blasts, and equipment meltdown. Burns that occur from arc blasts are due to thermal radiation and intense light. The use of proper clothing, work distances, and overcurrent protection can help reduce this risk. Wave blasts which can occur with a 25,000-amp arc can result in a force of approximately 480 pounds on the front of the body at 2 feet away. While these wave blasts can throw individuals away from the arc and resulting thermal radiation, serious ear damage and memory loss due to concussion can still occur. The pressure waves can also send equipment flying and can knock over walls. The melting of equipment is another risk of an arc flash. As equipment melts down, droplets of molten equipment metal can be projected by the arc blast. These droplets can cause burns and/or fires even at distances of 10 feet or more away.

Arc Flash Safety by Eaton Videos https://www.youtube.com/watch?v=uJUC2_w_mms

Arc Flash Awareness 2007 - National Institute for

Occupational Safety and Health, Part 1

https://www.youtube.com/watch?v=ORuXr-Kjw18

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https://www.youtube.com/watch?v=uJUC2_w_mms





As determined by the NFPA 70E, approach boundaries consist of four boundary levels determined by distance to protect from exposed live parts and arc flashes or blasts.

The three boundaries used to protect individuals from exposure to live parts include the following:

• Limited approach boundary – the closest approach for unqualified person unlessaccompanied by a qualified person.

• Restricted approach boundary – the closest approach without proper PPE for aqualified person. Careful attention of tools and movements that could be exposed to liveparts with unintentional movement.

• Prohibited approach boundary – distance a person must keep from live parts to preventflashover or arcing in the air. A person closer than the prohibited approach boundarywould essentially be in contact with a live part.

Electric Shock Boundaries to Live Parts 300 – 600 Volts

Limited Approach Boundary

3 feet 6 inches

Restricted Approach Boundary

1 foot

Prohibited Approach Boundary

1 inch Power Source

The fourth boundary is intended to protect against arc flash and is known as the flash protection boundary. At this boundary, PPE is required to prevent incurable burns in the event of an arc flash. In many transit agencies, only qualified persons are allowed to enter areas identified as “Arc Flash and Shock Hazard” locations.

Flash Protection Boundary to Live Parts 300 – 600 Volts

Flash Protection Boundary

4 feet Power Source

Your Agency Policy and Procedures Regarding Approach Boundaries PREVIEW ONLY

COURSE 207: SIGNAL POWER DISTRIBUTION INSPECTION & MAINTENANCE MODULE 2: Power Distribution Components


Primary Power Automatic Transfer Panel and Switch

The transfer equipment (panel and/or switch or relays) is the initial point of entry for commercial AC power into the signal system for some rail agencies. In the event the commercial voltage goes outside the value that is set, the transfer switch will transfer from the primary commercial power feed to an alternate primary power either generated by a generator or provided by an alternate commercial or agency-provided primary power feed and ultimately provides protection for the signal equipment and operation.

The signal maintainer should be aware of the three types of power being distributed through the transfer panel including primary power, alternate power (also known as secondary or standby power), and signal circuit power supply:

• Primary power – normal power and preferred power source• Alternate power (also known as Secondary or Standby power) –is power supplied to the

signal system when preferred power is unavailable or lost.• Power Supply to Signal and Related Circuits – sometimes known as “load power”, the

power provided to the signal system after leaving the transfer power switch, eitherprimary or secondary. The load side of the transfer switch supplies the CIL, and cablesdistribute power to the components in the signals system.

Figure 2.2 Primary Power at the Automatic Transfer Panel

Inspection and Maintenance for Transfer Panels and Switches

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Tools for inspection and maintenance of the automatic transfer panel switch include standard signal maintainer tools and standard signal maintainer PPE.

Inspection and maintenance tasks for the primary transfer panel begins with an understanding of all agency-specific power-down operating procedures. The signal maintainer then should ensure primary and secondary power to the panel switch has been de-energized. Agency recommendations and policies should be stated and must always be followed for inspection and maintenance practices.

General inspection and maintenance practices for these components include inspecting insulation, inspecting contacts for pitting or burning, inspecting the integrity of wiring for corrosion, cleaning and/or replacing contacts as per agency recommendations or policies, a visual inspection of terminations to ensure good connections, replace lamps as required, and test the timer relay test, also known as a timer test. The timer relay will keep the signal red until switching is complete. To test the timer relay, observe the relay to ensure it is working as intended. The FRA under 234.265 requires timer relays shall be maintained at not less than 90% nor more than 110% of the predetermined time interval. Most agencies consider lower than the predetermined interval as failing.

Figure 2.3 Timer Relay While some agencies utilize an in-house electrical department for troubleshooting and repair, signal maintainers are often tasked with general inspection and maintenance of transfer panels.

Caution: High voltage may be present. Signal maintainers should follow all-agency policies and procedures when working with or around high voltage.

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Testing for the automatic transfer panel and switch includes the following steps:

1. Verify stand-by power is available through indicator light or with a meter.2. Place in stand-by mode by either using test feature on transfer switch or removing

normal power3. Ensure the power transferred over to emergency / secondary power4. Restore normal power - verify transfer switch restores to normal by checking indicator

light or checking with the appropriate meter after appropriate time has expired peragency specific setting or via timer relay.

Figure 2.4 Transfer Switch

Caution: Always coordinate with your agency operational control center or obtain proper authority before completing any testing.

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• The commercial feed meter is locked in some agencies.• Cables should not be exposed.• Meters should be clean, free of debris and sealed.• All junction boxes and enclosures should be sealed and clean.• Tags and labels are legible.• All parts are properly position with no tripping hazards present.• Inspection for pinched wires or potential for grounds.• Terminations are properly maintained per agency standards.

Figure 2.6 Distribution Panel with Door Securely Closed

Figure 2.7 Distribution Panel with Door Open

2-3 GENERAL POWER DISTRIBUTION EQUIPMENT ANDCOMPONENTSGeneral power distribution equipment and components for signal systems include the distributive devices themselves along with circuit and equipment protection devices. These devices all serve various purposes and include the following:

• CIL• Insulate wires, cables and conduit• Load Center and Main Power Feed

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Wire and cable tests to be completed by signal maintainers include grounds tests and insulation resistance tests.

Wire and Cable Testing

Grounds Tests

The term “ground” in the power distribution system means just that: earth and ground all around including the ground outside where one walks, the dirt, rocks, etc. The earth is considered electrically neutral and to be at zero for reference in voltage measurements.

Per the National Electrical Code, a true earth ground is made up of a conductive pipe or rod driven into the earth to a minimum of 8 feet per depth.

Figure 2.9 Wire going to Ground

According to FRA 236.2, each circuit, the functioning of which affects the safety of train operations, shall be kept free of any ground or combination of grounds which will permit a flow of current equal to or in excess of 75 percent of the release value of any relay or other electromagnetic device in the circuit, except circuits which include any track rail and except the common return wires of single-wire, single-break, signal control circuits using a grounded common, and alternating current power distribution circuits which are grounded in the interest of safety.

For signal maintenance, two grounds tests should be performed: a traditional grounds test and a battery / energy busses grounds test.

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3. Take a voltage reading on the buss being tested to verify that meter is functioning andbuss voltage is at the correct level as shown below.

4. Leave one meter lead connected to one side of the energy buss and relocate the othermeter lead to ground as shown in Figure 30-2. If zero voltage potential is detected,take a voltage potential reading between the other side of the buss and ground. If bothsides of the buss read zero voltage to ground, a current reading to ground is notrequired. Record the buss nomenclature, buss voltage and current on the requiredground records, and repeat Step# 3 and 4 on remaining energy busses.

5. If voltage potential to ground is detected on any energy buss, a current reading toground must be taken.

Note: it is recommended that before this is done, precautions must be taken to ensurethat trains are not at or near the location involved.

Maximum allowable current to ground is 0.001 amperes on a low voltage buss (lessthan 110V) and 0.025 amperes on a high voltage buss (110V or higher). Currentreadings should be taken in progressive lower scales. If current exceeding this

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Figure 2.11 Typical Signal Cable

Test results are recorded as per agency specific guidelines for documentation. Figure is an example of a megger test documentation form used in SEPTA.

Figure 2.12 Megger Insulated Resistance Test Documentation Form

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Megger testing is comprised of three separate tests: the continuity test, the conductor to conductor test, and the conductor to earth insulation test.

Continuity Test Procedure

Preparation for Test

The first part of the test is the continuity test to ensure there is no break and the cable is continuous from end to end.

Test Procedure

1. Positively identify the conductor being tested starting with 12. Set multimeter to check resistance at 200 Ω range3. Check continuity of conductor 1 with respect to earth:

a. On one end of cable at location Ai. Apply negative lead from the meter to earth ground

ii. Apply positive lead to identified wire in the open conductor at the oppositeend

b. On opposite end of cable at location B, 2nd technician connects end of conductorto earth

c. Energize megger

Ohms Values –

• 0 Ω– 200k Ω– NG – remedy immediately if these values are found – cableis taken out of service

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Junction Boxes and Conduit

Junction Boxes are used throughout any power distribution system and contain electrical connections for protection and containment of those connections. Some junction boxes are located within the CIL and some are located outside. Depending on their purpose in the signal system, the shape of a junction box may vary. Conduit is a tube or channel used throughout a power distribution system to house to carry and protect wiring and signal circuits.

Inspection and Maintenance

Junction boxes should be observed to ensure they are properly placed, intact, relatively clean and free of excessive wear.

Figure 2.13 Junction Box at a Switch Machine

Conduit and cable trays holding wire and cable should be secure and in-place. Conduit that has become dislodged or broken should be replaced as per agency policy and direction.

Figure 2.14 Overhead Conduit and Cable Trays in a CIL

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Inverters are used to convert DC energy when AC energy is not available. Like a rectifier, the inverter does not produce power and the power is supplied by the DC source.


Prior to inspection and maintenance of batteries, rectifiers and inverters, signal maintainers should determine proper protection is in place for any work completed that may impact the signal system and identify any potential electrical hazards in the immediate area. Signal maintainers should obtain proper PPE to include safety glasses, aprons, gloves as well as any other PPE as determined by their agency.

Batteries should be inspected monthly. Any maintenance needed indicated at this inspection should also be completed. Steps to ensure inspection and maintenance of batteries is completed include:

• Ensure batteries are free of oxidation.o If oxidation is present on plates, use a small brush (similar to a tooth brush) to

clean the oxidation.• Ensure battery caps and vents are clean.

Figure 2.18 Battery Bank and Rectifiers

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• If batteries are a maintenance-free type, then replace the batteries per OEMrecommendations (an average of every five to six years).

• If batteries are not a maintenance-free type:o For Nickel Cadmium batteries: check mineral oil on top of water, add distilled

water as needed to the indicated “full” line.• Record the date, voltages per agency documentation procedures, side is cell one.

Figure 2.19 Battery Plates, courtesy of SEPTA

Battery Voltage Reading

Figure 2.20 Battery Test

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Transformers

A transformer is used in power distribution to increase or decrease voltage and current in an alternating current circuit. Transformers also provide a means to isolating one part of a circuit from another part of a circuit. Transformers are often found on the line side of a power source in a system or sub-system. For instance, a transformer typically be found on the line side of the main disconnect.

As discussed in Course 107, Introduction and Overview of Power Distribution for Signal Systems, three types of transformers are used in power distribution for signal systems which include: step-down transformers, step-up transformers, and isolation transformers.

Figure 2.25 Isolation Transformer

Inspection and Maintenance of Transformers

The inspection and maintenance of transformers involves a sensory inspection. The sensory inspection should include:

• Ensure the transformer is clean.• Ensure any bare connections are adequately covered/protected by means of safety caps or

hot caps.• Inspect the main input cap off (insulation on the wire connections) where there is high

voltage.

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POR has been de-energized and AC power is lost. In some cases, the light flashes or is in the light is visible in the central command center.

Figure 2.27 Power Off Relay

Figure 2.28 Electrical Schematic for Power Off Relay


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POR: The inspection and maintenance for a POR includes a test. The test includes the following steps in conjunction with batteries:

1. Check plug board, relay post contacts, e-post, and dust/clean relays. Complete a visualinspection of contacts and relays to ensure no pitting or debris are present.

2. Ensure testing schedule is up-to-date.3. Visually make sure relay drops and determine equipment is operating as designed.4. After test, ensure power is restored and POR is up.

Frequency Converters

A frequency converter is an electronic device that converts alternating current (AC) of one frequency to alternating current of another frequency.

Figure 2.29 Frequency Converter

Inspection and Maintenance of a Frequency Inverter

Caution:

• Be aware of all present voltages and potential electricalhazards.

• Ensure proper protection is in place for work affectingthe larger signal system.

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Required by NEC Article 110.9, circuit breakers must have an interrupting rate equal to or greater than the available fault current.

A circuit breaker panel also contains a neutral buss and grounding bar which is sealed off by a panel cover for safety.

Figure 2.30 Circuit Breakers


Circuit breakers should visually inspected. A visual inspection should include the following:

• Circuit breakers are clean.• Any labels are legible and clear.• Identify any tripped breakers.

o If a main breaker is tripped, the signal maintainer should follow their agencypolicy and procedure.

o If a feeder or branch circuit breaker is tripped, as indicated in some cases by agreen color, the breaker can be re-set but moving the switch back to the “On”position. The “On” position may be indicated by a red color.

Note: If a breaker is tripped, this may be an indication of a problem with circuits or equipment on either load or line side of the breaker. Affected circuits and equipment should be carefully observed and later monitored for proper operation. PREVIEW O

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• Using prints, verify accurate type and properly rated fuses are in place.• Ensure all fuses are seated properly.• Inspect for blown fuses as indicated by an indicator if available, discoloration or open

filament.• Check voltage across each fuse

Figure 2.33 Fuses in the CIL Figure 2.34 Properly Seated Fuses

Ground Wires

A ground wire creates a path for electric current to go to the earth, or ground. In powered equipment, metal parts are connected to ground through this wire to prevent voltage contact in the event electrical insulation fails. These connections also limit the build-up of static electricity which is important when handling flammable products or electrostatic sensitive devices. Electrical ground wires are typically green in color and should have appropriate current-carrying capability.

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Figure 2.36 GFCI

Inspection and Maintenance of a GFCI

The inspection and maintenance for a GFCI involves testing the trip function. To test the trip function of any GFI, push the test button and ensuring the GFI trips. Reset the GFCI test button when the test is completed.

Figure 2.37 GFCI Test Button

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Oil levels, oil quality, air filters and coolant should all be inspected during routine generator maintenance and inspection. The oil level of every generator should be inspected and changed per manufacturer recommendations. Likewise, air filters quality will be dependent on hours used, OEM recommendations, or not to exceed one year. Coolant levels should be inspected and maintained per OEM recommendations. Hours used should be annotated in a log book. Ensure overall cleanliness of the equipment and ensure labels are clear and legible. Inspect the integrity of ground and all electrical connections. Check the fuel level before starting. Generators should be refueled after cooling.

Figure 2.42 Portable Generator Figure 2.43 Portable Generator

Generators should be tested once a month to ensure they run as intended.

Portable Generator Hook Up Guidelines

1. Obtain permission from the dispatcher or control authority to apply temporary power feed2. (Familiarize yourself with the power circuits), consult power distribution plans,

determine power source voltage (110 volts, 220 volts), ensure generator matches sourcevoltage

3. Verify power is out, check the power feed with a multi-meter to ensure 0 volts4. Disconnect main and all other alternate back-up feeds5. Isolate all loads (circuits), open circuit breakers (open knife switch, open or remove fuse,

etc.)6. Verify proper phase of generator source7. Identify where temporary feed will be connected (inlet, breaker panel, or fuse block) or

directly connected to buss8. Terminate or connect temporary power supply cord or cable to house or location

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Figure 2.44 Solar Panels

Inspection and Maintenance of Generators

Prior to the inspection and maintenance of any solar panel, proper PPE should be obtained and used based on your agency recommendations. Inspection and maintenance of solar panels includes a battery check, a visual inspection and cleaning to include:

• Ensure solar panels are clean. Follow OEM recommendations for cleaning methods.• Inspect and replace battery per OEM and/or agency recommendations.• Ensure hydraulic fluid levels are in accordance with OEM and agency requirements,

typically marked in the hydraulic fluid reservoir.• Visually inspect wires in accordance with recommendations earlier outlined in this

module.• To confirm proper solar charging, open the charging fuse and use a meter set to DC to

read the amperage. Take readings across the fuse block. Solar panel size and amperagesare listed below:

o 36-watt Panel = 1 to 2 Amps*o 75-watt Panel = 3 to 4 Amps*o 100-watt Panel = 4 to 5 Amps*

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preview only - transit training...figure 1.2 arc flash, courtesy of fluke corporation and osha ....

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