1.1 1. Instrument Cannot Power On / Circuit Breaker Trips During Operation
1.1.1 1.1 Instrument Does Not Power On
If the instrument fails to power on, first verify that the AC power supply is available. Check the power outlet, power reel, or distribution panel to ensure the input power is functioning properly.
If the external power supply is normal, disconnect the instrument from the AC source and inspect the internal fuse. The fuse holder is located on the right side of the AC power inlet and can be removed using a flat-head screwdriver.
Fuse Specifications
Models Manufactured Before 2023
· 433F / 433A / 433E: 5 × 20 mm, 15 A
· 433B / 436E / 436ES / 437E / 437ER / 437ESR: 5 × 20 mm, 25 A
Models Manufactured in 2023 and Later
· 433F / 433K: 5 × 20 mm, 15 A
· 433B: 5 × 20 mm, 30 A
· All other models: 5 × 20 mm, 25 A
1.2 Instrument Powers On Normally, but the Distribution Breaker Trips During Testing
If the instrument powers on normally and the output voltage can be adjusted, but the power distribution breaker trips when operating the circuit breaker (such as during opening, closing, or spring charging), the following checks are recommended:
Verify that the distribution panel is properly grounded.
Inspect all power connections for loose or poor contacts.
Try using a different distribution panel or verify the power source with another electrical instrument.
If the external power supply is confirmed to be functioning correctly, the instrument itself may require inspection.
In this case, it is recommended to perform the timing test using one of the following methods:
1.3Method 1 – External Control Power Supply
Use an external AC or DC control power supply (or the existing control power supply of the circuit breaker) while allowing the tester to control the breaker opening and closing operations.
1.1.4Method 2 – External Trigger Mode
Use an independent external control power source to operate the circuit breaker manually.
The tester should be configured for External Close or External Open mode.
Both AC and DC control power supplies are supported.
