The test transformer operation box (also known as the control box, control console or voltage regulator) is the core control unit of the high-voltage test system, responsible for safely, smoothly and accurately regulating and outputting the voltage required by the high-voltage test transformer.
1. Main functions
Voltage regulation
As the core function, the output voltage can be adjusted smoothly and continuously either manually or automatically, and the voltage adjustment usually starts from 0V. Control
Implement control over the power input of the test transformer, covering the execution of key operation instructions such as startup, stop, and emergency stop. Measurement
Real-time display of the primary input voltage and current of the test transformer, as well as the secondary output voltage and current. The secondary electrical parameters can be directly read by the instrument or obtained through an external voltage divider. Protection
Integrates multiple protection functions to provide reliable security guarantees for the equipment and personnel during the test process.
Signal linkage
Equipped with interfaces for related equipment such as high-voltage test transformers, voltage dividers, and protection gap, supporting signal transmission and collaborative work among multiple devices.
II. Core Components
Reducer
Traditional type: Generally uses autotransformer reducers, including single-winding type or electric type, featuring simple structure and economic practicality.
Modern type: Uses induction-type reducers or electronic-type voltage regulation schemes, among which electronic-type voltage regulation can adopt thyristor voltage regulation technology. The advantage of induction-type reducers lies in large capacity and small waveform distortion; electronic-type voltage regulation has the characteristics of fast regulation speed, support for programmable control, and ease of achieving automated operation.
Control and Input Unit
Equipped with power switch, start/stop buttons, and emergency stop button, among which the emergency stop button is a key component for ensuring safety; also includes working status indicator lights, which can directly display the equipment status such as power, operation, and alarm.
Measurement and Display Unit
Equipped with input voltage meter and input current meter for monitoring the electrical parameters of the primary side of the test transformer.
Equipped with output voltage meter, usually reading the voltage value on the low-voltage side and converting it to the high-voltage side voltage according to the transformation ratio, or directly receiving the signal from an external voltage divider to display the high-voltage value.
Equipped with output current meter, generally reading the current value on the low-voltage side, or receiving the signal from an external sampling resistor to obtain the current data.
Protection Circuit
Overcurrent protection: When the output current exceeds the set threshold, quickly cut off the power supply to prevent equipment damage due to overcurrent.
Overvoltage protection: When the output voltage exceeds the set value, the protection device immediately acts to ensure system safety.
Zero position protection: Ensures that the reducer is in the zero position before starting the equipment to prevent damage to the equipment from voltage shock during startup.
Limit position protection: Used to prevent mechanical reducers from rotating past the head, protecting the mechanical structure of the reducer.
Time Relay: Can be used to set the duration of the withstand voltage test. When the test duration reaches the preset value, it automatically controls the voltage to drop back to zero.
Box
Usually uses a metal protective box, with grounding terminals on the box, ensuring the safety of the operation process through reliable grounding.
III. Working Process (Taking Power Frequency Withstand Voltage Test as an Example)
Preparation stage
Confirm the reliable grounding of the operation box, complete the connection of relevant equipment such as test transformers, test items, protection gap, etc., and rotate the reducer to zero position.
Connection and Setting stage
Connect the measurement lines, such as voltage dividers, etc., according to the test requirements to set the overcurrent protection value, test duration, etc. as key parameters.
Startup stage
Close the power switch, press the start button. At this time, the zero position protection function takes effect, allowing subsequent operations to be carried out.
Rising stage
Rise the voltage slowly and evenly by rotating the handwheel of the reducer (manual mode) or pressing the rise button (automatic mode). During the voltage rise process, closely monitor the values of the voltage meter and current meter. The value of the voltage meter should rise steadily to the preset test voltage; the value of the current meter is used to indicate the leakage current and capacitance current of the test item, and this value should remain stable without sudden changes.
Timing stage
When the voltage reaches the preset test voltage, start the timing program, which can be selected for manual or automatic timing. During the timing period, continuously monitor the value changes of the instruments.
Voltage reduction and end stage
When the test duration reaches the preset value, uniformly and rapidly reduce the voltage to zero position, then press the stop button, and finally disconnect the power switch.
Discharge stage
After the test item is fully discharged, the subsequent work such as changing the wiring can be carried out.
Post time: Jan-19-2026