Cummins/Onan OT3-UG-3 — Transfer Inhibit

For the Cummins/Onan OT3-UG-3.

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Procedure

1. 1. 7 OPERATION Automatic Operation The utility-to-generator set automatic transfer switch is set for automatic operation by placing con­ trol switches in the positions given below. The gen­ erator set must also be set for automatic operation. Test/Normai/Retransfer switch: Normal position. Motor Disconnect switch: Auto position. Operation selector switch (engine control): Remote position. (Two-wire start for water-cooled generator sets only.) Stop/Auto/Handcrank switch: Auto position. (Three-wire start for air-cooled gen­ erator sets only.) Manual Operation The transfer switch has operator handles for manu­ ally transferring the load. Use the following proce­ dure: rear side of the cabinet door presents a shock hazard that can cause severe persona/Injury or electrical contacts whenever the cabinet door Is open. If possible, remove all AC power to the transfer switch before manually operating the switch. If It Is necessary to perform manual operation with AC power connected, follow the "Safety Related Work Practices" listed In NFPA 70E. 1 . Open the cabinet door of the automatic trans­ fer switch.
2. 2. Move the Motor Disconnect switch to the Off position.
3. 3. Transfer - from the Normal to the Emer­ gency power source: A. Pull the upper manual operator handle down. B. Push the lower manual operator handle down. Retransfer -from the Emergency to the Nor­ mal power source: C. Pull the lower manual operator handle up. D. Push the upper manual operator handle up.
4. 4. Before moving the Motor Disconnect switch back to the Auto position, remember the trans- www . ElectricalPartManuals . com fer switch will transfer load to the active power source {if both power sources are available, it will transfer the load to the Normal source). eration results In rapid movement of the manual operator handles and presents a hazard of severe personal Injury. Keep hands clear of handles wher,r switching back to automatic operation.
5. 5. Move the Motor Disconnect switch to the Auto position.
6. 6. Close the cabinet door. Generator Set Exercise Run the generator set for at least 30 minutes once each week, with at least 50 percent load {if possi­ ble). If you do not have an optional exerciser, use the Test/NormaVRetransfer switch to test the gen­ erator set each week. The optional exerciser has preselected exercise periods and exercises the generator set automati­ cally with or without load depending on the position of the Exercise With/Without Load switch. If the Normal power source has an interruption while the generator set is exercising without load, the auto­ matic transfer switch will transfer the load to the generator set. Generator Set Start Test rear side of the cabinet door presents a shock hazard that can cause severe persona/Injury or electrical contacts whenever the C;flblnet door Is open. 1 . Place the Test With/Without Load selector switch, on the Power Sentry control, in the Without Load position. The Test WHh/Without Load selector switch must be In the WHhout Load position.
7. 2. Close the cabinet door. and the rear side of the cabinet door pre­ sents a shock hazard that can cause severe persona/ Injury or death. Close the cabinet door.
8. 3. Move the Test/NormaVRetransfEǔr switch to Test. The generator set should start and run.
9. 4. At the end of the test period, move the Test/ Normai/Retransfer switch to the Normal posi­ tion. The generator will stop.
10. 1. 8
11. 5. In anticipation of scheduled or automatic gen­ erator set exercise, check that the With/With­ out Load selector switches are in the desired
12. 6. Close and lock the cabinet door. With-Load Standby System Test rear side of the cabinet door presents a shock hazard that can cause severe persona/Injury or electrical contacts whenever the cabinet door Is open. 1 . Place the Test With/Without Load selector switch, on the Power Sentry control, in the With Load position. The Test With/Without Load selector switch must be In the With Load position In order to test with load.
13. 2. Close the cabinet door. and the rear side of the cabinet door pre­ sents a shock hazard that can cause severe persona/ Injury or death. Close the cabinet door.
14. 3. Move the Test/Normai/Retransfer switch to Test. The generator set should start and as­ sume the load after the transfer time delay.
15. 4. At the end of the test period, move the Test/ NormaVRetransfer switch to the Normal posi­ tion if you want to retransfer load back to the Normal power source after the retransfer time delay. To bypass the retransfertime delay and cause immediate load retra

Source: manual:962-0512 Onan OT III series (spec G) 40 to 1000 Amp Transfer Switch Service manual (11-1992).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.