Protection system for slip-ring induction motors
At a glance
To measure large currents at a low frequency (~1Hz) to check the performance of the regulator which was controlling a boiler feed pump motor at a power station.
Motor problems, such as excessive vibration, can be difficult to investigate because they can have both electrical and mechanical causes. Accurate measurement of the slip-frequency currents can help with the diagnosis.
The slip-frequency currents can be measured accurately using Rocoil rigid coils which have very good low-frequency response. The measurements can be used with a protection system to monitor phase imbalance and earth faults.