Cummins/Onan — Procedure (4 steps)

For these Cummins/Onan models: LT III, TGHAA.

Applies to: Cummins Onan Lt Iii, Cummins Onan Tghaa

Procedure

1. 6. 13 . . . . . . . . . . . . . . . . . . INCORRECT SERVICE OR REPLACEMENT OF PARTS CAN RESULT IN DEATH, SEVERE PERSONAL INJURY, AND/OR EQUIPMENT DAMAGE. SER- VICE PERSONNEL MUST BE QUALIFIED TO PERFORM ELECTRICAL AND/ OR MECHANICAL SERVICE. Redistribution or publication of this document, by any means, is strictly prohibited. OT3-UG-3 iii This manual includes the following symbols to indi- cate potentially dangerous conditions. Read the manual carefully and know when these conditions exist. Then take the necessary steps to protect per- sonnel and the equipment. This symbol warns of immediate hazards that will result in severe personal injury or death. unsafe practice that can result in severe per- sonal injury or death. unsafe practice that can result in personal inju- ry or product or property damage. High voltage in transfer switch components pres- ents serious shock hazards that can result in severe personal injury or death. Read and follow these suggestions. Keep the transfer switch cabinet closed and locked. Make sure only authorized personnel have the cabi- net and operational keys. Due to the serious shock hazard from high voltages within the cabinet, all service and adjustments to the transfer switch must be performed only by an electrician or authorized service representative. If the cabinet must be opened for any reason:
2. 1. Move the operation selector switch on the gen- erator set or Stop/Auto/Handcrank switch on the automatic transfer switch (whichever ap- plies) to Stop.
3. 2. Disconnect the starting batteries of the genera- tor set (remove the ground [–] lead first).
4. 3. Remove AC power to the automatic transfer switch. If the instructions require otherwise, shock hazard. Place rubber insulative mats on dry wood platforms over metal or concrete floors when working on any electrical equipment. Do not wear damp clothing (particularly wet shoes) or allow skin surfaces to be damp when handling any electrical equipment. Jewelry is a good conductor of electricity and should be removed when working on the electrical equipment. Do not work on this equipment when mentally or physically fatigued, or after consuming alcohol or any drug that makes the operation of equipment un- safe. Redistribution or publication of this document, by any means, is strictly prohibited. iv Redistribution or publication of this document, by any means, is strictly prohibited.
5. 1. 1
6. 1. Introduction ABOUT THIS MANUAL This manual contains service procedures for an LT diagram package that was shipped with the transfer tion. before starting any service procedures. Identify all al. Whenever troubleshooting, remember that the generator set, transfer switch, and utility power source are all interdependent. This transfer switch is available with two control packages: control package A has the standard fea- ture set, and control package B has a higher level of features. This manual covers both control pack- ages. TRANSFER SWITCH APPLICATION Transfer switches are an essential part of a build- ing’s standby or emergency power system. The Normal power source, commonly the utility line, is backed up by an Emergency power source, often a generator set. The transfer switch supplies the electrical load with power from one of these two power sources. The load is connected to the common of the transfer load is supplied with power from the Normal source (as illustrated). If the Normal power source is inter- rupted, the load is transferred to the Emergency power source. When Normal power returns, the load is retransferred to the Normal power source. The transfer and retransfer of the load are the two most basic functions of a transfer switch. AUTOMATIC TRANSFER SWITCHES Automatic transfer switches, capable of automatic operation without operator involvement, perform the following basic functions:
7. 1. Sense the interruption of the Normal power source.
8. 2. Send a start signal to the generator set (Emer- gency power source).
9. 3. Transfer the load to the Emergency power source.
10. 4. Sense the return of the Normal power source.
11. 5. Retransfer the load to the Normal power source.
12. 6. Send a stop signal to the generator set. LOAD NORMAL EMERGENCY OVERCURRENT PROTECTIVE DEVICE OVERCURRENT PROTECTIVE DEVICE (TYPICAL FUNCTION) Redistribution or publication of this document, by any means, is strictly prohibited.
13. 1. 2 TRANSFER SWITCH PROTECTION Transfer switches are continuously rated devices. With proper maintenance, they will carry load cur- rents up to their nameplate ratings for any time duration. Transfer switches are designed to safely withstand normally occurring surge currents from electrical devices in their load circuits. They are also designed to safely withstand the surge currents, which can occur on a short circuit or fault condition, as long as the available fault current does not ex- ceed the rating of the switch and it’s protective de- vice, and the transfer switch is installed with proper protective equipment. All automatic transfer switches are required to be installed with appropriate overcurrent protection on the normal source side of the transfer switch, and
14. 1. 1). Protective devices may be circuit breakers, tem components. A list of allowable protective equipment is affixed to the transfer switch. The listed protective device must be installed at some point in the circuit between the transfer switch and the electrical services that feed the device. REMOVING AND REPLACING ELECTRONIC CONTROL COMPONENTS rear side of the cabinet door presents a shock hazard that can cause severe personal injury or death. Disconnect connector J1/P1 before working on the electronic control system. Disconnecting J1/P1 removes all power to the door. Be sure to remove all power before replacing components. control system components. The transfer switch must always maintain com- pliance with any applicable codes and standards. Improper servicing can create an unsafe installation that might cause severe personal injury, death, and/ or equipment damage. For proper operation, f ield connections to Normal, REQUIREMENTS SWITCH SIZE TIGHTENING WIRE (AMPS) RANGE Ground Lug (All) 35 inlbs (4 N•m)
15. 4. 14 AWG CU 30 35 inlbs (4 N•m)
16. 3. 10 AWG CU 60 75 inlbs (8.5 N•m)
17. 2. 10 AWG CU 100 80 inlbs (9 N•m) 2/0-14 AWG CUAL 150 80 inlbs (9 N•m) 3/0-6 AWG CUAL 200 275 inlbs (31 N•m) 300 MCM-6 AWG CUAL 260 275 inlbs( 31 N•m) 400 MCM-6 AWG CUAL placement of parts can result in severe personal injury, death and/or equipment damage. Ser- vice personnel must be qualified to perform electrical and/or mechanical component instal- lation. MODEL IDENTIFICATION Identify your model by referring to the Model and Electrical characteristics are shown on the lower portion of the nameplate. The nameplate is located on the cabinet door. If it is necessary to contact a dealer or distributor re- garding the transfer switch, always give the com- listed on the nameplate. This information is neces- sary to properly identify your unit among the many types manufactured. feature/option codes for transfer switches at spec level J and above. On spec J transfer switches, the model number is made up of code segments that designate various features or options: LT 60 00000 J 1 2 3 4
18. 1. LT - 3-Pole Transfer Switch Series
19. 2. Ampere Rating 30 150 60 200 100 260
20. 3. Sequentially assigned spec number - issued for each specific combination of accessories, voltages, frequency and standards codes.

Source: manual:913-0503 Onan LT III 30-260 Service Manual (2-1997).pdf. Figures and steps are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.