How to test the transformer ratio?

Transformer ratio testing is an important step to ensure that the transformer is working properly, and is usually done using a transformer ratio tester. The following is the specific operation method:

1. Connect the ground wire

Ensure that the ground wire of the tester is properly grounded to ensure safe operation.

2. Wiring

According to the type of transformer, connect the test clamps correctly:

Single-phase transformer:

The yellow and black wire clips of the high voltage end cable are connected to the terminals on the high voltage side of the transformer under test.

The yellow and black clamps of the low-voltage end cable are connected to the terminals on the low-voltage side of the transformer under test.

Three-phase transformer

(Mode 1): The 3-color clamps (yellow, green and red) of the high-voltage and low-voltage cables are connected to phase A, phase B and phase C respectively.

(Mode 2): The 4-color clamps (yellow, green, red and black) of the cables at the HV and LV ends are connected to phase A, phase B, phase C and neutral point (O) respectively.

3. Variable Ratio Measurement

After all the wiring is completed, turn on the power switch, or press the “reset” button, the screen will display the power-on interface.

Select the measurement mode:

Mode 1:

Press F4 key to enter the menu.

Automatic test: measure the ratio, group number and no-load current of three-phase transformer under unknown conditions.

Three-phase test: when the connection mode of the high-voltage side is known, press F4 to enter the setting menu, select the high-voltage connection mode, and measure the low-voltage connection mode, ratio, group number and no-load current of the three-phase transformer.

Single-phase test: used to measure single-phase transformer or PT, CVT (160V test), press F4 and then measure ratio, polarity and no-load current.

Z-type transformer test: used to measure Z-type transformer, after selecting this menu, press F4 to test its low-voltage connection mode, ratio, group number and no-load current.

Mode II:

Press F4 to enter the menu, use F2 and F3 keys to select high voltage and low voltage connection mode, then press F4 to start the test.