Multi-station Transformer Verification Device

I.overview

The multi-station transformer verification device is a new generation of transformer verification device developed to adapt to the fast and accurate characteristics of modern transformer verification.

The multi-station transformer verification device consists of a transformer calibrator, a current and voltage load box, a control cabinet, and a special test bench for current transformers. On the premise of maintaining the original technical characteristics, the rapid measurement of current transformers, the rapid positioning of test points, and the coverage of load boxes and transformers with various ratios have been greatly improved.

II.Main feature

1. The fine adjustment of the multi-station transformer verification device adopts the program-controlled source technology, which makes the positioning of the test point faster and more accurate.

2. The multi-station transformer verification device has a qualitative improvement in the measurement speed of multiple current transformers, and can measure twelve current transformers of any ratio in 3-5 minutes.

3. The multi-station transformer verification device is equipped with a 5A standard current transformer, the current load box is configured with a 5A load value of 2.5VA-60VA, and the voltage load box is configured with a 100V load value from 1.25VA-158.75VA, which can basically meet the needs of users. requirements. The load box can be switched automatically during measurement.

4. The multi-station transformer verification device can perform the regulation and non-regulation measurement of the transformer, and the user can specify the measurement of any percentage during the measurement.

III.Technical index

1.multi-station transformer verification device Ambient conditions for use

Temperature: 5C~40C

Relative humidity: <80% (25C)

Altitude: <2500m

Power frequency: 50Hz 0.5Hz

Power supply voltage: 220V5V

2.Transformer calibrator related parameters

⑴.Measurement range:

In-phase component (%): 0.0001~200.0 Resolution: 0.0001

Orthogonal component (min): 0.001~999.9 Resolution: 0.001

Impedance(): 0.0001~60.0 Resolution: 0.0001

Admittance (ms): 0.0001~60.0 Resolution: 0.0001

⑵.Basic error:

In-phase component: X=(X×2%+Y×2%2 words)

Orthogonal component: Y=(Y×2%+X×2%5 words)

"X", "Y" - the displayed value of the instrument

"5 words" - the quantization error of the instrument

Percentage table: Level 1

⑶. Scope of work:

Current: (1%-149%) In (In=5A) (5%-149%) In (In=1A)

⑷. Workload:

Current: To to Tx<0.12 cos=1

⑸. Polarity error indication

When the rated working current is more than 5% and the error exceeds 180%, there should be a polarity indication.

Note：If it is more than 10% of the rated working current, the proper polarity indication still does not appear, indicating that the software is faulty, please do not increase the current to avoid burning the instrument.

⑹. Ratio error indication

More than 5% of the rated working current, when the error exceeds 30% but less than 180%, there should be a ratio error indication.

⑺. Insulation and withstａnd voltage test and description:

Terminal Tx and ( ) terminals are connected

Terminals K and D are not connected with ( ) terminals

The power socket can withstａnd 1.5KV to the shell, 1min withstａnd voltage

⑻. Dimensions: (L 445×W 330×H 140) mm3

⑼.Weight: 10kg

IV.Control cabinet for multi-station transformer verification device

The control cabinet part of the multi-station transformer verification device is controlled by the transformer calibrator, which outputs a certain voltage according to the command, so that the transformer can reach the predetermined working current or working voltage.

1.Control circuit

As shown in the picture above: After the control cabinet is powered on, the blue indicator light of the start button is on, indicating that the control cabinet is powered on. Select the measurement object through the calibrator, make the corresponding contactor pull in, and make the corresponding output terminal have voltage output. When an abnormal situation occurs, you can press the stop button to disconnect the output of the platform.

The 10kVA voltage regulator is the main output source for coarse adjustment and voltage regulation; the power source is for fine adjustment and voltage adjustment. For example, if the secondary current is 20% of the current transformer of 5A, first the large voltage regulator adjusts 16%, and the power source adjusts the remaining 4%. The advantages of using this method are high pressure regulation fineness, accurate positioning, fast and convenient use.

V.multi-station transformer verification device

The multi-station transformer verification device (referred to as the transformer verification device) is a special workbench body designed for testing multiple transformers. It is matched with the transformer calibrator, load box and control cabinet to form HMQT-Imulti-station transformer verification device. It consists of a standard current transformer with a current booster, a primary current control board, a secondary current control board, and a wire crimping device. The positions of the test benches for each part are shown in the following figure:

1、multi-station transformer verification device function

The multi-station transformer verification device has the following functions:

(1) Fully automatic test can be performed on multiple current transformers under test according to the predetermined order;

(2) The transformer test bench can perform fixed-point test on one of the multiple current transformers being tested;

⑶. Display the serial number of the current transformer being measured;

⑷. Under the control of the host computer, the automatic switching of the transformation ratio of the standard transformer can be carried out.

VI、Polarity test

Before the error test of current transformer and voltage transformer, it is generally necessary to check the polarity.

According to the regulations, the primary windings of the current transformer are marked as L1, L2 (P1, P2)..., and the secondary windings are marked as K1, K2 (S1, S2).... When the primary current enters the primary winding from L1, the secondary current flows out from K1. Such a polarity sign is called subtractive polarity. L1 or K1 is called the polar end or the end of the same name, and some use a dot next to the winding to indicate the polar end.

According to the regulations, the primary windings of the voltage transformer are marked as X, A1, A2...., and the secondary windings are marked as x, a1, a2.... When the high-voltage end of the primary winding is A, the low-voltage end is X, or the power supply current is input from the A-end, the high-voltage end of the secondary winding is correspondingly a, the low-voltage end is correspondingly x, or the secondary load current is output from the corresponding a-end . Such a polarity sign is called subtractive polarity. The polar terminal is the terminal with the same name. In voltage transformers, some use the high voltage terminals A and a as the polar terminals, and some use the low voltage terminals (usually ground terminals) X and X as the polar terminals, and there is no unified regulation. Especially for three-phase voltage transformers, it is even more difficult to determine which phase is the polar end. For the convenience of the following description, here we take the high-voltage terminals, namely A and a, as the polar terminals, and the low-voltage (ground) terminals, namely X and x, as the non-polar terminals.

To check whether the polarity marking of the transformer winding is correct, the following methods are usually used:

1. DC method verification grade

2, the tandem method verification level

3. Check the polarity on the transformer calibrator

The HGQA-C transformer calibrator has a polarity indication function. In this way, a polarity check can be performed in advance at the same time as the error test. At this time, the connection between the standard voltage transformer and the tested voltage transformer and the transformer calibrator must be wired according to the provisions of the error test.

If the polarity of the transformer is wrong or the measured data f>180% due to wiring reasons, it will display the wrong polarity. Press the "OK" key to continue measuring data, press any key again to exit the measurement; press the "Exit" key to end the measurement directly. If the ratio difference of the measured data is greater than 20% and less than 180%, the ratio error will be displayed.

VII、Demagnetization

If the current transformer is cut off under high current, or the secondary winding is accidentally opened during operation, and after the test is carried out with DC current, residual magnetism may be generated in the core of the transformer, which will reduce the magnetic permeability of the core and affect the impact. Therefore, before the error test of the current transformer, the transformer should generally be demagnetized to eliminate the influence of residual magnetism on the error. There are two demagnetization methods that are usually introduced: open circuit (strong magnetic field) demagnetization and closed circuit (large load) demagnetization.

1. Open circuit (strong magnetic field) demagnetization

The primary and secondary windings are all open, and the primary or secondary windings are supplied with power frequency current, which increases from zero to 99% or 120% of the rated current, and then decreases evenly and slowly to zero. Repeat this process 2-3 times, and at the same time reduce the current passed in each time by 1200%, 80%, and 20% of the rated current. After demagnetization is completed, the secondary winding should be short-circuited before cutting off the current.

2. Closed circuit (large load) demagnetization

A resistance equivalent to 10-20 times its rated load is connected to the secondary winding, and the primary winding is connected to the power frequency current, which increases from zero to about 120% of the rated current, and then decreases evenly and slowly to zero. Repeat this process 2-3 times, while reducing the resistance load connected each time by 99%, 50%, and 20%.

If it is a multi-stage current transformer, during the demagnetization process, the secondary windings that are not demagnetized should be short-circuited.

3. The integrated transformer verification device adopts closed-circuit demagnetization for the current transformer

⑴. Conventional demagnetization steps

① Wiring in accordance with the regulations for calibrating current transformers

②Turn on the power of the bench and the calibrator

③Menu select manual demagnetization

④Enter the measurement interface

⑤Press the up key

⑥ Slowly decrease after reaching 120%

⑦Complete

⑵.Concise way demagnetization steps

① Wiring in accordance with the regulations for calibrating current transformers

②The measurement object of the verification device is selected as CT

③Turn on the verification device, open the upper computer software and the power of the calibrator

④The upper computer software enters the CT measurement interface

⑤Click to demagnetize

⑥Complete