Transmitting electricity safely and without interruption is a complex, demanding process, especially at medium voltage (MV). Among the biggest problems are phase-to-phase and phase-to-earth faults. When a fault occurs, fast detection and response are critical for energy continuity. This is where the fault indicator comes in.
What Is a Fault Indicator?
A fault indicator is a compact device, usually incorporating current transformers (CTs), that detects phase-to-phase and phase-to-earth faults on medium-voltage networks and gives the operator a visual signal.
Used in MV switchgear, underground cable boxes, substations and distribution panels, these devices quickly locate fault points in the energy system. The Revotek fault indicator also has a communication port for sending data to SCADA systems, enabling remote monitoring and control.
How Does a Fault Indicator Work?
The operating principle is quite smart and can be summarised as follows:
1. Detection via Current Transformers (CTs)
The high fault current that flows during a fault is detected by the current transformer inside the system.
The CT monitors the sudden change in current at the moment of the fault and sends a signal to the device.
2. Threshold-Based Decision
The device contains preset threshold values.
These values allow it to distinguish normal operating currents from fault currents.
It is triggered when a phase-to-phase short circuit or a phase-to-earth fault is detected.
3. Fault Indication
When a fault is detected, the LED on the device lights up and the contacts operate.
Field staff can then easily see where the fault is.
4. Reset Function
Some models reset automatically, while others are reset manually.
Why Use One?
- Shorter outages: The faulty section is identified quickly, so power is restored sooner.
- Guidance for field teams: Finding the fault on large distribution networks is difficult; these devices make the job easier.
- Time and cost savings: They shorten fault-finding time and prevent unnecessary interventions.
- Strategic support for network management: They provide data for fault analysis and system improvements.
Applications
- MV overhead or underground cable systems
- Ring-main distribution systems
- Compact substations
- Urban MV distribution lines
- MV switchgear in industrial facilities
At Revotek Elektronik , our fault indicators developed specifically for MV systems make fault detection on distribution lines faster, more reliable and more user-friendly. Designed around field requirements and backed by local production, our products offer quality, durability and technical support.