YDQC Serial light-duty high voltage testing transformer is single-phase transformer, connection group symbol II. For operation process of single high voltage testing transformer, connect AC 220V (or 380V for above 10kVA) voltage to power supply control box, regulating 0 to 200V (0 to 400V for above 10kVA) voltage, through self-coupling voltage regulator (outside attached for above 50kVA) inside power
supply control box, to primary winding of testing transformer, according to the principle of electromagnetic induction, high voltage necessary for tests can be obtained at high voltage winding of the testing transformer. The principle is shown in Fig.2.
1. Working principle diagram of single YDQC high voltage testing transformer
R -current limiting resistor; C-high voltage filtering capacitor; Zx-product to be tested; G-silicon stack short circuit rod; FRC- capacitance-resistance divider; V-high voltage voltmeter for divider; uA-microammeter; D-high voltage rectification silicon stack.
Connect working circuit for DC leakage test according to Fig.5 and considering Fig.3. X terminal (high voltage tail) of high voltage winding of testing transformer, F terminal of instrument measure winding, housing of testing transformer and housing of power supply control box must be reliably connected to ground.
Before connecting power supply, voltage regulator of power supply control box must be adjusted to zero. After power supply is on, green indicator lamp is on, press start button, red indicator lamp is on, showing testing transformer has been connected to control power supply, starting voltage stepping up.
Turn clockwise hand wheel of voltage regulator from zero position at even speed for voltage stepping up (for voltage stepping up mode, there are quick voltage stepping up, i.e., 20S stepwise voltage stepping up, slow voltage stepping up, i.e., 60S stepwise voltage stepping up and most slow voltage stepping up to be selected). Voltage will be increased from zero, at selected stepping up speed, to necessary rated testing voltage or reference voltage at rated DC current. During testing pay full attention to indication of DC high voltage voltmeter and leakage ammeter and state of product to be tested. At the end of the test, quick reduce high voltage to zero at even speed, press stop button, high and low voltage output will stop. Cut off power supply. Now, completely discharge product to be tested and testing equipment itself with DC high voltage discharge rod.
Notes in operation of DC leakage test
(1) Persons for testing shall take respective responsibilities, setting safety distance on the testing site, carefully check product to be tested and ground of testing transformer, a person must be specially assigned for supervising safety and observing product to be tested.
(2) Before testing, exterior wiring shall be disconnected from product to be tested, product to be tested shall be discharged completely. Main portion of the product to be tested shall be clear, absolutely dry, to avoid damage of product to be tested or error for testing data.
(3) For large capacity product to be tested (capacitor, extended cable and etc.), during testing, slowly perform voltage stepping up, prevent too heavy charge current of the product to be tested from burning microammeter, if necessary, voltage stepping up in stage, respectively read stable reading of microammeter at every voltage.
(4) During testing, pay full attention to product to be tested, microammeter and testing equipment, in case of flicker, breakdown and so on, immediately decrease voltage, cut off power supply, and find out the reasons.
V. high voltage testing transformer Accessories
The following accessories are only for choice, if necessary, additional payment.
1. XZC series power supply control box, capacity: 1kVA to 5kVA, input voltage: 220V
2. KZC series power supply control box, capacity: 10kVA to 300kVA, input voltage: 220V or 380V
3. Digital microammeter: QSA
4. High voltage filtering capacitor: 0.01MF, 40 to 100kV
5. High voltage DC discharge rod: FZ- 70, 140, 210kV