Accessories
3.7 Accessories for the Electronic Trip Unit
3WJ Air Circuit breakers
90 Operating Instructions, 12/2022, L1V30828903001-01
Result of the N transformer test
If the LED flashes (1 s ON, 1 s OFF), this signals a fault with the measuring transformer of the
neutral conductor. This might be because a measuring transformer has not been installed
(e.g. no external neutral conductor transformer connected), or it has been connected
incorrectly, or is defective.
If the LED starts flashing quickly (0.5 s ON, 0.5 s OFF), this signals a fault with the energy
transformer of the neutral conductor. This might be because an energy transformer has not
been installed (e.g. when an external neutral conductor transformer is connected), or it has
been connected incorrectly, or is defective.
Testing the tripping function
• Charge the stored-energy spring mechanism manually.
• Close the Circuit Breaker
To test the tripping function, press either "L", "S", "I", "N", or "G".
The Circuit Breaker trips after the set delay time plus 2 seconds. The reason for tripping can
be queried via the "QUERY" button on the electronic trip unit. To do so, the electronic trip unit
must have been active for at least 20 minutes. If the Circuit Breaker does not trip, the
electronic trip unit is either not equipped with the relevant protection function or is defective.
Testing the measured value display
After the tripping test, the capability of the system to store the reasons for tripping must be
tested via the "QUERY" button when the ETU is deactivated.
To test the measured value display, press "I" and "N" simultaneously.
Over a period of 30 s, a current is simulated in L1, L2, L3, N, and G consecutively via the
measuring transformer. The LEDs of the corresponding transformers flash. The test is
considered successful when current is displayed at the relevant point.
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