Shaft Ground Monitoring: Assurance Monitoring System

OEM recommended shaft voltage checks are now safer, easier and more accurate than ever before.

—— Technical specifications
  • Enclosure NEMA 4X rated.
  • Operating Temperature Range:  +5 to +150F (-15 to +70 C)
  • Input Power Options:   AC, 85-264Vac, 47-440 Hz, 10W; DC, 20-32Vdc, 10W.
  • Real time shaft voltage, ground current and rope condition are visible on an easy to read touch screen display:
    • Voltage Zero to Peak: Range 0 to 200 V
    • Current Zero to Peak: Range 0 to 70 A
    • Voltage RMS: 0 to 50 V RMS
    • Current RMS: 0 to 30 A RMS
    • Voltage DC: +/- 25 V
    • Current DC: +/- 30 A
    • Rope Status: Pass/Fail
  • Manual input tracks date of rope change and enables operator to reset rope fault after change or inspection

Connectivity to Plant Systems:

  • The values measured above are transmitted to the plant historian or other management software via seven 4×20 mA channels and Modbus RTU.
  • For RMS and Peak measurements, 4 mA = zero and 20 mA = a full-scale reading.
  • For DC measurements, 4 mA = full-scale minus reading and 20 mA = full-scale positive reading.

Accuracy: RMS and DC readings are within +/- 2% of source.

Frequency Response: Down 10% between 10 Hz and 100 kHz

Pulse Response: Captures pulses 10 microseconds or wider. 100 kHz or slower. (based on laboratory tests with
flat-topped pulses)

Notes for Pulse Response: Negative-going pulses are converted to positive and displayed as positive readings. Accuracy, based on tests with regularly repeating pulses: +/- 2% of reading plus 5 digits, or better. Single-pulse capture holds each maximum value for 1 second. Accuracy may vary depending on the width of the pulse and its timing relationship to the internal sampling rate. Variations of around 10 to 20% of reading are possible. For example, a single 10V pulse might be displayed as anywhere between 8 and 10 volts.

Remote Test Points Readings:
  • Shaft Voltage Test Points connect directly to the isolated metering rope on the shaft and case ground. Use O-scope or Voltmeter to measure.
  • Ground Current Test Points are connected to the ground current hall effect sensor drivers. Scale is 30 mV per Amp. Use O-scope or Voltmeter to measure.
  • Rope Wear Test Points are connected to the rope status sense circuitry. Measurement of 0 V indicates the rope is in good condition. Measurement of +5 V indicates a wear indicator has worn through and is now in a fault condition.