Introduction to test methods of transformer capacity tester

Instructions

The following will be divided into two parts to introduce: active capacity load loss and passive loss measurement part.

(1) Active transformer capacity and load loss measurement part

1. Basic concepts

Active capacity test: Determine the actual capacity value of a transformer through some necessary data; thereby checking whether the nameplate capacity of the tested transformer is true.

2. Test method

The capacity tester is equipped with three test clamps (yellow, green, and red). Each clamp leads to two test wires, one thick wire and one thin wire. The clamp meter is connected to the aviation plug on the panel through an adapter wire; follow the corresponding Connect the color and thickness of the adapter cable to the jack of the corresponding color and thickness, and then clamp the clamps according to the color on each phase terminal of the high-voltage side of the transformer under test. The low-voltage side of the transformer should be well shorted with special short wires. catch. as the picture shows:

After connecting the lines, select the capacity test item on the main interface. At this time, you will enter the capacity parameter setting screen and follow the following steps to set:

u Set the current temperature, use the up and down keys to point the hand pointer to the 'Current Temperature' option, and use the left and right keys to adjust the temperature value. It is required to be as accurate as possible. It is best to refer to the indication value of the thermometer.

u Set the rated voltage of the high-voltage side, use the up and down keys to point the hand pointer to the 'High rated voltage' option, and use the left and right keys to adjust the high rated voltage range. For example, if the transformer under test is a 10KV/400V distribution transformer, set this item to 10KV

u Set the transformer type, use the up and down keys to point the hand pointer to the 'Transformer Type' option, and use the left and right keys to adjust the option so that it matches the nameplate.

u Set the tap position, use the up and down keys to point the hand pointer to the 'tap position' option, use the left and right keys to adjust the option, usually tap to the 2 tap position, if the tap of the transformer under test is at Otherwise, set this option to the correct location.

u Use the up and down keys to point the hand pointer to the 'Tested Sample Number' option, and use the left and right keys to adjust the option to a certain number value.

u Press the start button to perform the test, and the results will be automatically retained on the LCD

u Select 'Save' to save the results to the internal memory. If you do not need to save, do not select this option.

u Select 'Print' to print out the test results.

The wiring method of the active load test is exactly the same as the capacity test, and the operation is equally simple. It is worth noting that the parameter setting of the active load test is to use the third item 'Parameter Settings' in the main interface, and it must be set correctly.

(2) Passive transformer loss measurement part

1. Basic concepts

No-load test: Apply the rated voltage of the sine wave rated frequency from a certain winding of the transformer (generally from the secondary low-voltage side), open the other windings, and measure the no-load current and no-load loss. If the test conditions are limited and the power supply voltage cannot reach the rated voltage, the test can be performed under non-rated voltage conditions. This test method has a large error and is generally only used to check whether the transformer is faulty. Only when the test voltage reaches more than 80% of the rated voltage It can be used to test no-load loss.

Short circuit test: artificially short-circuit the low-voltage high-current side of the transformer, pass the test voltage at rated frequency from the rated tap of the coil on the high-voltage side, so that the current in the winding reaches the rated value, and then measure the input power and applied voltage ( That is, short circuit loss and short circuit voltage) and current value.

2. Test method

Different test items are introduced below:

(1) Measurement of no-load loss of three-phase transformer with single-phase power supply: When the on-site test conditions cannot meet the requirements of using three-phase power supply for no-load test, single-phase power supply (AC 220V) can be used to conduct no-load test of three-phase transformer. test. Each phase of the transformer is tested separately, and the test results are automatically converted to the three-phase power test. See the appendix for specific wiring diagrams.

Use the Ua and Ub of the instrument to measure the voltage, use the A-phase current loop to measure the current, and then power up the low-voltage side Ao, Bo, and Co of the transformer under test for testing.

(2) To measure the no-load loss of the transformer with three-phase power supply: open the non-test end of the transformer and connect the wires as shown in the figure.

Three-phase power supply measuring transformer no-load loss

(3) Measure the short-circuit loss of single-phase transformer: Connect according to Figure 19.

Single-phase transformer short circuit loss measurement

(4) Three-phase three-wire power supply to measure the short-circuit loss of the transformer: Apply the three-phase test power from the high-voltage side of the transformer, and use a special short-circuit wire to short-circuit the low-voltage side well, as shown in Figure 20.

Three-phase power supply measuring transformer short circuit loss

Note: The method we use here is equivalent to the previous two-power meter method. The voltage measurement is the three-phase voltage value of UAB, UCA and UCB, and the result is the average of the three phases. The power loss only measures the two-phase power of PAB and PCB, and the total loss is two sum of phase power losses.