VGM-100 Voltage & Ground Fault Monitor: 125V
Whether it’s a substation panel, switchgear cubicle, or remote telecom shelter, the VGM‑100 keeps a constant watch on your 24 V DC bus and flagging ground faults that other monitors miss. The full‑color touchscreen simplifies everything: adjust thresholds, delay timers, and IP settings in seconds. Built‑in Ethernet with Modbus TCP/IP plus four Form‑C contacts plug seamlessly into existing SCADA or automation systems so every alert reaches the right screen.
Setup is straightforward—clip the compact unit to a DIN rail, tie in two sense wires from the battery bus, and power it off that same 24 V source. No auxiliary PSU, no extra cabling. Certified to IEEE/ANSI C37.90a for noise immunity and rated for 0 – 55 °C, it’s ready for harsh service.
Choose the VGM‑100 for a cost‑effective, no‑nonsense way to secure your 24‑volt string while keeping operators fully informed.
- Color touchscreen simple interface
- Ethernet connectivity to web interface, (4) Form C Contacts
- Modbus TCP/IP output for all measured parameters
- Simple installation with mounting kit for DIN rail or wall mount
- Monitors 24V batteries
- Configurations available for different needs
| Measurement Range | Battery Voltage: TBD Fault Resistance Limit Set: 1 – 100 kΩ |
| Fault Resistance Limit Set | 1 – 100 kΩ |
| Output Contacts | (4) Form C |
| Contact Rating | 125 VAC/VDC: 0.5 A 30 VDC: 2 A |
| Maximum Switching Power | 60 W |
| Power Requirements | Powered by connected battery DC voltage |
| Noise Immunity | IEEE/ANSI C37.90a‑1989 compliant |
| Time Delay to Alarm | Adjustable 1 – 999 seconds |
| Operating Environment | Temp 0 – 55 °C (32 – 131 °F); Humidity 0 – 95 % RH |
| Dimensions / Weight | 147 × 91 × 45 mm (5.77 × 3.56 × 1.77 in) / 284 g (10 oz) |
Product Literature
Support Documents
How does the VGM detect ground fault conditions?
DC ground fault detection is determined by measurement of the voltage imbalance relative to ground. These measurements are made through very high resistance divider networks. One establishes the ground reference, and the other measures the positive and negative DC voltages. These values are applied to analog‑to‑digital converters, and the microcontroller firmware compares the sum of these DC values to the ground reference. If the sum is 0, the DC voltage is perfectly balanced relative to ground. If the sum is positive or negative, the DC voltage is unbalanced positive or negative. User settings determine the extent of imbalance that will result in an alarm condition.
Will the VGM detect a ground fault via a leaked battery jar?
The system will detect a ground fault caused by a leaking battery jar provided the ground‑fault‑resistance setting is configured correctly. Because a leak creates a resistive path to ground, the VGM senses the resulting voltage imbalance and triggers an alarm as long as the path‑to‑ground resistance is lower than the set threshold.
What is the k ohm limit for ground detection?
Up to 300 kΩ.
What are the contact ratings for the Form C contacts?
The relays are rated at 60 W with a maximum of 220 V DC and 2 A. Practically, they can switch 2 A at 30 V DC or less, 0.5 A at 125 V DC, and only 0.009 A at 220 V DC. Use an external relay if higher ratings are required.
Do the connections between the monitor and the batteries need to be fused?
No. The monitor includes an internal fuse for self‑protection. You may still choose to fuse the external wiring to guard against short circuits.
Is the VGM CSA certified?
The VGM‑Series is CE certified. For Canadian customers, CSA certification is not required for DC‑powered units. Contact Eagle Eye for clarification on specific certification needs.