When a Small Leakage Becomes a Bigger Question
A control panel can run normally for months. Then one day, insulation deterioration, moisture or wiring damage creates a path to earth. The leakage may be small, but ignoring it can affect equipment safety and plant operation.
That is why an earth leakage relay should be selected as part of the protection strategy, not simply added as another panel component.
Good earth leakage protection starts with detecting the right current at the right time.
What Does an Earth Leakage Relay Do?
An ELR relay monitors leakage current flowing towards earth. When the measured value crosses the selected threshold for the set duration, its output can initiate a trip or alarm.
Minilec offers dedicated earth leakage relay models within its monitoring relay range.
The relay is useful only when its sensing and trip settings match the application.
How Does CBCT-Based Detection Work?
A CBCT for earth leakage relay surrounds the phase conductors and neutral, where applicable. Under healthy conditions, the currents balance. When current leaks to earth, the balance changes and the CBCT sends a signal to the relay.
Minilec recommends considering CBCT primary/secondary current, inner diameter, outer diameter and relay model while ordering.
The CBCT and relay should be selected as one protection system.
Earth Fault Relay vs Earth Leakage Relay
The terms are sometimes used loosely, but the required sensing level matters.
Minilec’s S2 ELR2 Earth Leakage Relay uses a 300 mA CBCT secondary input with adjustable leakage and trip-delay settings. By comparison, Minilec earth fault models such as F3 EFR2 use 1 A / 5 A CT or CBCT secondary inputs for earth/ground fault monitoring. Minilec
Do not select by product name alone—select by the fault level you need to detect.
Where Are ELRs Used?
Minilec lists applications including generator panels, AMF panels, MCC panels, synchronising panels, motor control panels, ACBs and MCCBs with shunt-trip arrangements. Minilec
Different panels may require different leakage settings and response logic.
Earth Leakage Relay Selection Checklist
Before specifying an earth leakage protection relay, check:
- Expected leakage-current range
- Correct CBCT size and secondary rating
- Adjustable leakage setting
- Required trip-time delay
- Reset logic
- Panel type and application risk
Correct selection reduces both protection gaps and unnecessary trips.
Minilec ELR Solutions
Minilec’s earth leakage range includes models such as S2 ELR2 and F3 ELR2, supported by CBCT options for different panel requirements. Minilec
Talk to Minilec for earth leakage relay selection based on your application.
