Insulation fault location, how does it work?
The insulation fault location system consists of an insulation fault locator and an insulation fault evaluator in conjunction with one or more measuring current transformers.
The insulation fault locator is integrated in the ISOMETER® iso685-x-P.
What is the procedure?
- Start troubleshooting by activating the insulation fault locator, the ISOMETER®.
- The active conductors are briefly connected to earth.
- An electronic current limiter, this connection and the insulation fault create a closed circuit in which a mains voltage-dependent test current IT flows. The test current is limited to a maximum value.
- The locating current pulse flows from the insulation fault locator via the live lines, the insulation fault Rf and via the earth line (PE line) back to the insulation fault locator.
- The locating current signal is detected by all measuring current transformers in the circuit and evaluated by EDS insulation fault evaluators.
- The fault location can be localized based on the measuring current transformer/circuit assignment.
What is the difference between manual insulation fault location?
A distinction is made between manual insulation fault location:
- A portable insulation fault evaluator is used for insulation fault location in subordinate outgoing circuits, in addition to the permanently installed EDS system.
- If no insulation fault locator is available, a portable insulation fault locator is used.
- If the IT system is de-energized, a portable insulation fault locator with an integrated measuring voltage source is used.
What is the distinguishing feature of the main circuit/control circuit?
The main difference between the two applications is the significantly reduced test current for use in control circuits and the response sensitivity.
Features of a switching function?
- All measuring channels are scanned in parallel during insulation fault location.
- Maximum scanning time is ≤ 10 s.
- After this time, the relay contact of the faulty measuring channel switches.
- This switching contact can be used to switch off the faulty outgoing circuit via a switching element.
