Instruments & Control



Challenge :

PLTP Gunung Salak is one of geothermal power plant operated by Indonesia Power, has an old hydraulic servo valve controller to operate condensate supply and discharge valve. This controller is fully electronic based and the spare part already obsolete. 

They want to upgrade the existing controller of Condenser Inlet Valve and Condenser Discharge Valve using the state-of -the-art technology to increase its realiability and sparepart availibility.

The customer want a latest control system technology to control their hydraulic operated valve which still use the old servo valve which require +/- 100mA signal. As our AO module could only generate 4-20mA signal, we need another module to convert from 4-20mA to +/-100mA. The other challange is, as the valves quite old, the valve respons not smooth for small displacement.

For this project, we use NEXUS onCore Control System from Baker Hughes. We provide a set of baseplate with NEXUS onCore installed inside and routing the field cable from existing control system to new control system. Then, we perform stroke test to ensure the valve could operate to a full stroke and tune the PID controller to obtain a better valve response to setpoint change.

By migrating to digital control system user could save space and power consumption of the control system. This also open another possibility to integrate another field equipment, such as Variable Speed Drive of Condensate Pump to this system. 

Also, by migrating to digital system, user could monitor the servo valve condition by monitoring its current consumption during steady state. As found during commissioning test, broken servo valve has higher current consumption during steady state condition.

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