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Cummins/Onan OTPCA — Service Procedure

For the Cummins/Onan OTPCA.

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Procedure

  1. 1. Sense the interruption of the Source 1 power.
  2. 2. Transfer the load to the Source 2.
  3. 3. Sense the return of Source 1.
  4. 4. Retransfer the load to Source 1. Level 2 controllers can control a two-utility configu- ration for prime power. One utility is designated the preferred source. The control automatically trans- fers the load between the two utilities and detects alarm conditions. The exercise routine is not avail- able in this configuration. The operator can select either source as the pre- ferred source. See the Digital Display Menu System section. GENERATOR-TO-GENERATOR CONTROL The genset-to-genset control can be set up for two types of applications: • Prime Power – Two gensets provide all of the power (utility power is not available) • Dual Standby – Two gensets are used to back up utility power Note: The Test/Exercise function and Load Shed feature are not available in this configuration. If one genset fails to operate within the specified range of voltage and frequency, the transfer switch automatically starts and connects the other genset. Preferred Source Selection With both prime power and dual standby applica- tions, either genset can be set up to be the preferred source. If the preferred source is changed while one of the gensets is running, the control starts the sec- ond genset and transfers the load to it, when it be- comes available. Time Delays All the time delays are factory set and are adjust- able through the front panel display. The factory set- tings are: TDNE 10 SEC TDEN 600 SEC TDESa 3 SEC TDECa 600 SEC TDESb 3 SEC TDECb 600 SEC Note: TDESa and TDECa are for the Source 2 gen- set and TDESb and TDECb are for the Source 1 genset. Use the Time Delay sub-menus under Setup or the PC Service tool to change the settings. Prime Power (Plant to Plant) Operation In prime power applications, utility power is not available. The system includes one transfer switch and two gensets. One genset is always running and supplying power to the load while the other genset is the backup genset. An external power supply is not needed in this application. Preferred Source Selection – Under normal op- eration, one genset is designated as the preferred source and supplies power to the load. The second genset is the backup power source. If the preferred genset fails, the backup genset starts and the trans- fer switch transfers the load to the backup genset. At any time, the PC Service tool or the Test sub- menu can be used to designate either genset (Source 1 or Source 2) as the preferred genset. If the preferred genset is changed and the backup genset becomes the preferred genset, the transfer switch transfers the load to the new preferred gen- set when it becomes available. The unit that is car- rying the load is always considered the preferred source. Automatic Changeover – The transfer switch can be set up to change the preferred source automati- cally by enabling the changeover timer. The Time Delay sub-menus under Setup or the PC Service tool can be used to enable the changeover timer and specify a changeover delay time period. The automatic changeover timer automatically changes the preferred source and transfers the load to the new preferred genset after a TDEN time delay. After the transfer is complete, the control initi- ates a cool-down period (TDEC) on the old pre- ferred genset before shutting it down. The old pre- Redistribution or publication of this document, by any means, is strictly prohibited.

Source: manual:962-0516A Onan OTPC (40-1000 Amp) Transfer Switch Service manual (10-2002).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.