Simode with frequency drive

S

Thread Starter

Ster_pan

On site we had an application with a direct starting motor, 6 poles, 53A nominal current, giving power to the turning gear of a steam turbine.

In our trial to get lower speed of steam turbine turning gear and also having soft start we installed a frequency converter downstream the power contactor. the problem faced during commisioning was that the turning gear, originally consumed 27A in DOL power contactor and with inverter consumed 19A but the simocode was reading 5 A lower that the cut off limit. As result the SImocode was losing the feedback signal and tripping from RTS fault.

We understand that the use of frequency converter (inverter) is not the best way downstream of a simocode but now can you please share any experience with that problem? The existing Simocode is 25-100A, the motor current is 27A in DOL but 19A in inverter.

Some thoughts:
1) connect a three phaseheater 3 kw in parallel with inverter supply to increase the current,
2) pass two times each wire from Simocode in order to understand double current,
3) make complete new installation with direct feed of power to the inverter and bypassing the Simocode.
 
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