Western Power
Western Power
Pinjar Gas Turbines - Cranking MotorsVibration Monitoring
The Western Power Pinjar Gas Turbines Plant is one of eleven gas-fired power generation plants in Western Australia. It is the 3rd largest contributor to WA's power grid, producing up to 586MW of electricity for the state.
As gas turbines are generally very well engineered, the failure rates for these machines is relatively low. When they do fail, the cause is usually due to the failure of external systems, such as lubrication systems, gas supply systems, or cranking systems. The cranking systems are our focus point, as these are required to run the turbine up to operating speed and warm up the system. Failure of a cranking motor means that when electricity demand spikes, the unit cannot fire up and blackouts can result.
Being a rotating machine, the cranking motor's most common failure points are the bearings. Since vibration monitoring of bearings is a proven method and a standard for determining the condition and life of bearings and their elements, this was the method chosen to monitor the cranking motors.
A Bruel & Kjaer AS-062 industrial accelerometer was mounted on each bearing casing (on both Drive-end and non-drive-end bearings) to capture the overall level of vibration evident in each bearing. An analyser can also be connected directly to the accelerometers through the monitoring unit to view spectral data for a thorough vibration analysis.
Back in the Equipment Building, each pair of accelerometers is wired to a SIMS Compact Monitor. The SIMS has configurable trip points that were set during commissioning at pre-determined levels of vibration. If the vibration level reaches either of the limits (low or high), then the corresponding relays are activated allowing warnings to be sent back to the control room, or automatic shutdown of the motor.