Test System CAT + SAT for CB Testing

Test system CAT+SAT provides a complete set of functional tests for a circuit breaker including:

Timing test,
Contact resistance measurement (DRM and SRM),
Undervoltage condition test,
Motor test,
Minimum trip voltage test,
Coil resistance measurement,
Motion measurement.

All these tests are performed without change of connection during testing.

To establish the test system CAT+SAT and perform all above listed tests, the CAT and SAT devices should be connected to the circuit breaker auxiliary circuitry as shown in Figure 1. Motor output of the SAT device is directly connected to the motor terminals. Coils outputs of the SAT device are connected to the Coil supply inputs of the CAT device. Coil control outputs of the CAT device are connected to the appropriate Open and Close coil terminals.

Also, SAT should be connected to the CAT device by USB cable to provide its control from the touch screen of the CAT device.

Figure 1. Connection scheme for CAT + SAT test system

There are two testing modes with the test system CAT+SAT:

Performing the tests supported by the CAT device, while the SAT device serves as a power supply for CB auxiliary circuit;
Performing tests supported by the SAT device, while the CAT device serves as a connection between the SAT and a circuit breaker under the test.

For both testing modes all settings related to the SAT device are set from the touch screen display of the CAT device and all results obtained by SAT device are shown on the display of the CAT device.

The first test mode

In the first testing mode the SAT is used as the power supply for the coils and motor, providing voltage levels of up to 300 V DC or 250 V AC.

With the voltage generated at the coil’s outputs of the SAT device (working as a power supply) it is possible to perform the following tests with the accompanying CAT device:

Timing tests (O, C, CO etc.) at rated coil supply voltage,
Undervoltage condition timing tests,
Static resistance measurement (available for CATs with a built-in Micro Ohmmeter),
Dynamic resistance measurement (available for CATs with a built-in Micro Ohmmeter)

Since SAT is a controllable power source, the rated coil voltage and minimum coil supply voltage (for undervoltage condition simulation) can be set and generated.

The second test mode

In the second testing mode, the SAT works as a coil analyzer. Internal relays in the CAT device need to be closed to provide connection of the SAT coil outputs to the control circuit (to the trip and close coils) of the circuit breaker. To enter this testing mode, it is needed to select “Coil/ Motor tests” option on the display of the CAT device and then select desired test in the following screen (Figure 2).