On-line rotor temperature measurements

Abstract

On-line temperature measurements on hydrogenerators are usually limited to those read by resistive thermal detectors (RTD) on stators and global temperature of the cooling air and water at the input and output of the heat exchangers. Data shows that the proportion of generators where the temperature rise on the rotor is larger than on the stator is non negligible. With such units, temperature monitoring of the rotor should be considered. This paper presents the characterization of an infra-red thermal sensor installed on the stator side to measure the rotor. A single sensor can therefore scan every pole passing in front of it. Preliminary measurements on generators owned by Hydro-Québec (HQ) and Électricité de France (EDF) are presented along with details on the characterization at HQ's research laboratories (IREQ) in a controlled environment.

Analysis of Thermo-Mechanical Stress in Fiber Bragg Grating Used for Hydro-Generator Rotor Temperature Monitoring

“…Another available monitoring method is to insert an infrared (IR) probe through a vent duct in the stator to measure the temperature of the poles passing in front of the probe. However it does not define the hot spots of the field winding and the measurement depends on the emissivity of the pole surface which is not always known and can be affected by contamination [3].…”

“…field windings and pole connections) is not a trivial task. Such procedure was avoided in the past due to issues related to cost, reliability, difficulty of instrumentation and signal extraction [3], [5].…”

“…Above some acceptable limits these factors lead to premature aging of the rotor. Thermal stress normally affects the turn and ground insulation of the rotor poles [1]- [3]. This may lead to early refurbishment of the poles or in some cases to ground faults which can cause extensive damage.…”