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We just had our Wartsila-Cummings and Leroy Somer generator being serviced – taken out to a workshop and after the repair, reinstalled back at our plant. The repair is for the engine parts only – the alternator parts were only serviced.

The alternator is Leroy Somer LSA 54M75, 2450 KVA, 415 V, 50 Hz, 4 poles. AVR is Leroy Somer R 449 and R 726 (see attached diagrams). After the installation we could not get the voltage ( we get 50 V instead of 415V). Site reps has checked the connections and even testing the AVR – OK.

At this time the contractor rep. did try to use an external battery – he did connect an external battery to the excitation unit for 2 seconds during rated speed and managed to get the 415 VAC as required. But when he put back the R 449 connection back to the excitation unit – we could not get the voltage level of 415 V but manage only get 50 V.

R 449 has connection from an auxilliary winding for power supply, we measured the voltage level of this auxilliary winding during rated speed and get about 88V.

Another guy came in yesterday and brought in external battery 12 V 200AH and connected to the excitation unit (he removed the cables from R 449 to the excitation unit and connected that to the battery). He did not disconnect other cables. After running for 2 minutes to rated speed, the cables from auxilliary winding to the R 449 got burnt and we stopped the test. However during the test we did get the voltage of about 488 V at the terminal.

The differential relay tripped at this time even though the genset was running without any connection to the bus-bar.

Hope to get your assistance.

Thank you

We just had our Wartsila-Cummings and Leroy Somer generator being serviced – taken out to a workshop and after the repair, reinstalled back at our plant. The repair is for the engine parts only – the alternator parts were only serviced.

The alternator is Leroy Somer LSA 54M75, 2450 KVA, 415 V, 50 Hz, 4 poles. AVR is Leroy Somer R 449 and R 726 (see attached diagrams). After the installation we could not get the voltage ( we get 50 V instead of 415V). Site reps has checked the connections and even testing the AVR – OK.

At this time the contractor rep. did try to use an external battery – he did connect an external battery to the excitation unit for 2 seconds during rated speed and managed to get the 415 VAC as required. But when he put back the R 449 connection back to the excitation unit – we could not get the voltage level of 415 V but manage only get 50 V.

R 449 has connection from an auxilliary winding for power supply, we measured the voltage level of this auxilliary winding during rated speed and get about 88V.

Another guy came in yesterday and brought in external battery 12 V 200AH and connected to the excitation unit (he removed the cables from R 449 to the excitation unit and connected that to the battery). He did not disconnect other cables. After running for 2 minutes to rated speed, the cables from auxilliary winding to the R 449 got burnt and we stopped the test. However during the test we did get the voltage of about 488 V at the terminal.

The differential relay tripped at this time even though the genset was running without any connection to the bus-bar.

Hope to get your assistance.

Thank you