Torsional strain in vertical recirculating pump shafts at the Peachbottom Nuclear Power Station was of interest in determining the source of shaft cracking. Philadelphia Electric Company asked ANCO to install torsional strain gages and telemetry instrumentation in order to monitor strain amplitude and frequencies during normal operations. ANCO’s system, now in successful operation for over two years, has allowed verification of analytical models and provided data for fatigue life prediction and maintenance.

FM TRANSMITTER ELIMINATES SLIP RINGS

Rotating equipment and shafts are found throughout power plants. Often there is a need to measure stress or other parameters at some critical point on the shaft or attached rotating component. In the past, noisy and unreliable slip rings were used to transfer the signals from the rotating member to a recorder (and to power the transducer). More recently, small shaft-mounted FM transmitters with integrated signal conditioning and induction power units have been developed that greatly improve the state of the art.

ANCO has experience with a number of telemetry systems and is an authorized installer of the Wireless Data Systems (formerly Acurex) equipment line. ANCO finds the WDS line to be the most accurate and reliable available today.

MANY SYSTEM PARAMETERS CAN BE MEASURED

While stress is the most often measured parameter, torsion, bending, axial load, power transfer, pressure, acceleration, and vibration caN also be monitored. Using such systems, plant personnel can monitor the health and performance of critical rotating components. A predictive and preventative maintenance program can be formulated to include: Shaft crack detection, monitoring of fatigue life, alignment, and power output, accurate measurement of loads in gear teeth and bearings, as well as, instabilities in (rotor) hydrodynamics and (turbine-generator) torsional vibrations.