Current transformer test method of transformer tester

CTP-1000B variable frequency transformer tester is a new generation of CT and PT testing instrument developed on the basis of traditional voltage transformer volt ampere characteristic tester based on voltage regulator, voltage booster and current transformer, after widely listening to users’ opinions, after a lot of market research and in-depth theoretical research. The device adopts high-performance DSP and FPGA, and advanced manufacturing technology to ensure stable and reliable product performance, complete function, high degree of automation, high test efficiency and is in the leading level in China. It is a professional test instrument for transformer in power industry.

1. The wiring steps of current transformer test are as follows

Step 1: according to the description of CT test items described in Table 1, conduct wiring according to figure 1 or figure 2.
 
Table 2.5 Description of CT test items

Figure 2.1 Connection mode of CT DC resistance, excitation and transformation ratio test

Figure 2.2 Connection mode of CT secondary load test
 
Step 2: other windings of the same CT are open circuit, the primary side of CT should be grounded, and the equipment should also be grounded.
Step 3: turn on the power and prepare for parameter setting.
 

2. Test parameter setting of current transformer

The test parameter setting interface is shown in Figure 3.

 
The parameter setting steps are as follows:
Rotate the mouse to switch the cursor and select the test item to be carried out. When the cursor stays at a certain test item, the screen displays the parameter settings related to the test item; when the cursor leaves the test item, the screen displays the wiring diagram corresponding to the selected test item.
 
The parameters that can be set are as follows:
 
(1) Number: input the number of this test, which is convenient for printing, saving, management and searching.
(2) Rated secondary current Isn: the rated current at the secondary side of current transformer, generally 1A and 5A.
(3) Grade: the level of the tested winding. For CT, there are 8 options, such as P, TPY, metering, PR, PX, TPS, TPX, TPZ.
(4) Current temperature: the winding temperature during the test. Generally, the air temperature during the test can be input.
(5) Rated frequency: optional values are: 50 Hz or 60 Hz.
(6) Maximum test current: generally, it can be set as the rated secondary current value. For TPY class CT, it can be set to 2 times of the rated secondary current value. For class P CT, if it is 5P40 and rated secondary current is 1A, then the maximum test current should be set as 5% * 40 * 1A = 2A; if it is 10P15 and rated secondary current is 5A, then the maximum test current should be set as 10% * 15 * 5A = 7.5A.
 
If you want to see the following results, you need to set the basic parameters accurately (it is recommended that you set them).
(1) Turn ratio error, ratio difference and phase difference
(2) Accurate calculation of limit electromotive force and its corresponding compound error
(3) The accurate limit value of the safety factor and the safety factor of the instrument
(4) Measured transient area coefficient, peak instantaneous error and secondary time constant
For different levels of CT, the parameter settings are also different, as shown in Table 2.

1. Step 5: select the start button on the right to test.

2. Test results of frequency conversion transformer comprehensive tester
The results are shown in Figure 4.

Figure4 Test result interface
For different levels of CT and selected test items, the test results are also different, as shown in Table 3.
Table 3