Description
2.9 Self-monitoring and diagnostics
3WA1 air circuit breaker
176 Equipment Manual, 02/2023, 92310000002-06
2.9.2 Software-assisted testing
In order to check and log the parameterized protection settings and the functionality of
the circuit breaker, the 3WA air circuit breaker offers the possibility of software-assisted
testing. These tests can be easily performed during commissioning, inspection and
maintenance (see Chapter Inspection and maintenance (Page 387)) or service.
In contrast to previously used test equipment and test procedures, software-assisted
testing offers simple test execution, without assembly work on the circuit breaker and
comprehensive documentation. It is therefore more effective, more fail-safe, and its
mode of operation makes it very flexible and meaningful.
2.9.2.1 Circuit breaker operating principle
The basis for testing an 3WA air circuit breaker is its operating principle.
The following graphic shows in simplified form what you have to test on a 3WA air circuit
breaker in order to be able to verify its functionality.
Operating principle
The air circuit breaker uses current sensors to measure the current currently flowing
through the main contacts. The current sensors convert the primary current into an
analog measured signal. The analog measured signal is converted into a digital
measured signal in an analog-to-digital converter.
The digital measured signal is compared with the set protection settings in protection
electronics. If the current measured by the main contacts exceeds the set limits, the
tripping solenoid F5 is activated immediately or after the set delay time. The tripping
solenoid F5 unlatches a breaker latching mechanism. The energy stored in the breaker
latching mechanism opens the main contacts of the circuit breaker and thus interrupts
the electric circuits.
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