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Generator Condition Monitor – Explosion-Proof Design (GCM-X)


Corrective action prompted by early warning of generator overheating can mean the difference between a brief shutdown for minor repairs and a major overhaul involving weeks or even months of costly downtime. E/One pioneered the development of the Generator Condition Monitor (GCM) and in more than 1,500 applications worldwide, operators have the opportunity of taking corrective action if and when a critical situation occurs.

Building on more than three decades of proven field experience, and incorporating international requirements for hazardous area locations, the Generator Condition Monitor-Explosion-Proof Design (GCM-X) assures a new level in generator performance, reliability, and safety.

How the GCM-X Works

Predictive maintenance is an essential tool in electric power generation. The GCM-X uses real-time detection to give early warning of generator overheating and potential failure.

High concentrations of submicron particles (pyrolytic products) are produced whenever any materials within the generator are heated sufficiently to produce thermal decomposition. These "hotspots" can lead to catastrophic failure if not detected in a timely manner.

When present in hydrogen, pyrolytic products are quickly detected by the sensitive ion chamber of the GCM-X. The GCM-X warns of impending generator failure faster and more reliably than temperature sensors such as RTD's or thermocouples.

If an emergency situation occurs, upon detection of generator hotspots, the GCM-X microprocessor initiates and monitors an alarm verification sequence. If the alarm is confirmed, a verified alarm indication is given; alarm contacts are switched; and a fixed amount of the hydrogen flow automatically passes through the sampling system. Particles are then collected for laboratory analysis to determine their source.

Alarm confirmation is quickly made by the automatic alarm verification system, which activates the solenoid valve in the filter/solenoid valve assembly. All the hydrogen then passes through the filter, which removes the submicron particles. If the alarm is valid and thermally produced particles are present, their removal will cause the ion chamber detector to return to its normal level, confirming the presence of pyrolytic particles and the existence of overheating.

GCM-X Features and Benefits

  • Microprocessor-based with self-diagnostics
  • Flameproof, intrinsically safe design
  • Differential pressure transmitter for stable flow control
  • Dual bar graphs for flow and output
  • Separate warning and trouble indicators
  • Automatic alarm verification
  • Optional remote control/display and communication
  • Easy installation
  • Maintenance-free operation


Download the GCM-X brochure


GCM-X Specifications

Measurement Characteristics
Technology Principle Ionization Chamber
Flow Rate Adjusted by internal valve
Differential Pressure 4" to 5" (102 mm to 127 mm) minimum
Bar Graph Readout  
Normal Operation 80% of scale, typical
Alarm Condition 50% of scale, typical
Flow 1.5
Electrical Characteristics  
Power - Input Voltage 115/230 VAC
Input Frequency 50/60 Hz
Input Power 100 Watts
Inrush Current 2A
Output Signal 4-20 mA current output, self-powered (0 to 100%)
Flow output signal 4-20 mA current output, self-powered (0 to 3")
Output, Relays 3A @ 250 VAC
Alarm, NO and NC 3A @ 30 VDC resistive
Warning, NO and NC 100 mA @ 125 VDC resistive
Trouble, NO and NC  
Mechanical Characteristics  
Overall Dimensions 21.8"W x 23.6"D x 30.8"H
Weight 240 lbs. (110 Kg)
Temperature 32-149 F (0-65 C)
Relative Humidity 0-95%
Area Classification ATEX Zone 2, H2
Gas Pressure 100 psi maximum
Gas Connections 150 lbs., ½" pipe flanges, standard