Benefits You Gain by Monitoring with the VCM
| BENEFITS | No Brush |
Un-monitored brush system |
VCM-C & brush system |
VCM-E & brush system |
| Prevent Shaft Current Damage | NO |
? |
YES |
YES |
| Shaft Current Sparking Confined or Controlled | NO |
? |
YES |
YES |
| Train Performance Tracking, Aiding Operation | NO |
NO |
YES |
YES |
| Continuous Train Performance Sensing & Tracking | NO |
NO |
NO |
YES |
| Continuous Train Trending Aiding in Maintenance Scheduling | NO |
NO |
NO |
YES |
| FEATURES | No Brush |
Un-monitored brush system |
VCM-C & brush system |
VCM-E & brush system |
| Divert Shaft Current Harmlessly to Ground | NO |
? |
YES |
YES |
| LCD Display of Shaft Voltage and Brush Current | NO |
NO |
YES |
YES |
| LED Alarm Indicating Zero Grounding Current | NO |
NO |
YES |
YES |
| LED Alarm Indicating Excessive Shaft Voltage | NO |
NO |
YES |
YES |
| Continuous Tracking of Peak Shaft Voltage, (Scale = 1 to 100V) | NO |
NO |
NO |
YES |
| Continuous Tracking of Brush Current, (Scale = .1mA to 100A) | NO |
NO |
NO |
YES |
| 4-2O mA Peak Shaft Voltage Signal to Control Room | NO |
NO |
NO |
YES |
| Alarm Excessive Peak Voltage to Control Room | NO |
NO |
NO |
YES |
| 4-2O mA Peak Brush Current Signal to Control Room | NO |
NO |
NO |
YES |
| Alarm Zero Brush Current to Control Room | NO |
NO |
NO |
YES |
Summary
When the shaft voltage and grounding brush current are monitored with the VCM-C, you gain protection from current damage to shaft bearings and guidance for improved operation. The VCM-E gives you the added benefit of continuous information and trending for effective planned and predictive maintenance.
Notes
Circuitry Power
VCM-C: powered by nine volt transistor battery when the spring-loaded PUSH-TO-READ button is pressed. No external circuitry is required.
VCM-E: powered by 120 volt or 240 volt external supply, AC or DC, for continuous monitoring and signal transmission to control room.
Sparking Avoidance in Explosive Environments
VCM-C: Select Shaft Voltage, Press PUSH-TO-READ Button
The brush ground circuit will open inside the explosion-proof enclosure to avoid possible
sparking outside as the brush is raised and the ground connection is interrupted.
VCM-E: Multiple brushes are required for continuous shaft grounding feature. One grounding brush should always remain in contact with the shaft as protection while the other brush is raised for access and replacement.
Current and Voltage
Zero current may be an indication that the brush grounding circuit is open.
VCM-C: Current and voltage ranges are fixed. The VCM reaches its heating limit when the average current exceeds two amperes. The meter will display current spikes accurately at peak limits not exceeding 20 amperes. Currents in the range of 1mA average and 10mA may not register on the display because they are below the level where bearing damage will occur. Readings not monitored continuously are uncertain indicators of condition and performance.
VCM-E: Current measuring shunts and voltage metering ranges can be set from 1mA to 100A to match the characteristics of most any unit. Continuous monitoring and trending of train performance provides accurate assessment of the brush grounding system performance and provides useful operational and maintenance information.