I. Equipment Overview
The high and low voltage switch cabinet power-on test bench is a mobile test power supply device that integrates multiple voltage levels and current output capabilities. This equipment does not belong to precise measurement instruments for specific electrical parameters. Its core function is to be a mobile dedicated power supply device with voltage regulation, power distribution, and status monitoring indicators.
The core working principle of the equipment is based on internal multi-winding isolation transformers, autotransformers, and other core components, which convert the external 380V industrial power supply into various fixed and adjustable AC and DC voltages suitable for the secondary system of the switch cabinet. Operators can safely and conveniently provide preset test power for different specifications of switch cabinets through the conversion switch, operation buttons, and indicator instruments on the equipment panel, thereby testing the action reliability of components such as relays, contactors, instruments, and intelligent protection devices inside the cabinet, and verifying the correctness of the equipment circuit wiring, ensuring that the overall operating performance of the switch cabinet meets the standards.
II. Main Technical Functions and Output Characteristics
The standard high and low voltage switch cabinet power-on test bench is equipped with multiple independent core functional modules, which can meet the requirements of power-on tests, protection calibration, and circuit detection for various switch cabinets. The specific output characteristics and functions are as follows:
(1) AC Power Output Unit
1. Fixed Output
Mainly adapted to the basic circuit testing requirements of equipment such as lighting, heating, and control, with conventional single-phase 220V socket-type output and three-phase 380V terminal-type output. This part of the output is directly powered on when the equipment main power is started, without additional adjustment, and can quickly complete the basic circuit power-on test.
2. Adjustable Output
Used to simulate voltage fluctuations in different working conditions on site and precise verification of the action values of various protection devices. The equipment is conventionally equipped with multiple voltage output levels for three-phase adjustable voltage, including 0-430V, 0-520V, 0-100V, etc., which can cover most of the AC circuit testing scenarios for high and low voltage switch cabinets. It also includes 0-10A single-phase or three-phase adjustable current output, which can simulate the overcurrent operation conditions of the equipment, precisely detecting the overcurrent action characteristics and response performance of the protection devices inside the cabinet.
(2) DC Power Output Unit
1. Adjustable Output
Conventionally provides continuous adjustable DC voltages of 0-260V or 0-300V, which can replace the DC screen equipment of the substation and provide stable and adjustable DC working power for the closing and opening operation mechanisms of the switch cabinet, as well as comprehensive protection devices and secondary control circuits, suitable for the performance testing of various DC action components.
2. Fixed Output
Integrated with 24V, 36V, 110V, 220V industry-standard DC voltage levels for fixed output ports, without voltage adjustment, it can quickly supply power to low-voltage control circuits, signal indication equipment, and small protection components, significantly improving the efficiency of routine simple tests.
(3) Operation and Safety Protection Logic
1. Electrical Interlock Function
To avoid equipment failure caused by multiple voltage sources being connected in series and circulating current, all adjustable output circuits of the equipment are equipped with exclusive electrical interlock logic, covering three-phase adjustable high voltage, three-phase adjustable low voltage, and DC adjustable voltage for all adjustable output channels. During equipment operation, only one adjustable output can be started at a time, from the hardware logic level to completely prevent accidental operation that may cause equipment damage or circuit short circuits.
2. Zero Position Protection Function
All adjustable output circuits are equipped with zero position start protection mechanisms, which are the core safety protection design. Before starting the adjustable output of the equipment, the handwheel of the voltage regulator must be returned to zero position, and the system can then be connected to the output circuit, ensuring that the voltage and current are started smoothly from zero, with full control of the working conditions, effectively avoiding damage to components due to pressure start-up.
III. Standard Operating Procedures and Safety Regulations Standardized operation is the core prerequisite for ensuring accurate test results and avoiding personal injury and equipment damage risks. The general standard operating procedures and safety guidelines for the equipment are as follows:
(1) Test Preparation
Move the test bench smoothly to the area where the switch cabinet to be tested is located, ensuring that the equipment is placed stably without tilting or shaking. Prioritize the connection of protective grounding wires to ensure reliable grounding and good contact. This is the most critical safety step before the operation. Then, select the appropriate cross-sectional area of dedicated cables and reliably connect the input terminals of the test bench to the external three-phase four-wire 380V industrial power supply. Check that the connections are firm without loosening and there are no exposed copper wires.
(2) Secondary Circuit Wiring
Before the operation, it is necessary to confirm that the main output switch of the test bench and all branch control switches are in the off state, and all regulators are set to zero. Follow the electrical drawing specifications to connect the secondary control lines, closing lines, energy storage lines, and other test cables of the switch cabinet to be tested to the dedicated output terminals on the rear panel of the test bench, checking that the wiring circuits are correct and there are no errors, and avoiding incorrect connections, missed connections, or false connections.
(3) Equipment Startup and Parameter Adjustment
1. Close the main power switch of the test bench and observe the status of the power indicator lights on the panel to confirm that the equipment is powered on normally and there are no abnormal alarms.
2. As an example of using a three-phase adjustable 0-100V output: First, rotate the handwheel of the corresponding circuit regulator counterclockwise to zero position, confirm that the zero position protection is unlocked, then press the circuit start button. Wait for the output contactor to engage and the circuit to enter the ready-to-power state.
3. Slowly and uniformly rotate the handwheel of the regulator in the clockwise direction, observe the values of the panel voltmeter and ammeter in real time, gradually increase the voltage to the required rated parameters of the test, strictly avoid rapid and large voltage adjustments to prevent sudden voltage changes from impacting the tested equipment.
(4) Test Completion and Wire Removal Operations
After the test is completed, follow the principle of “return to zero first, then stop the machine”, first slowly turn all regulator handwheels to zero position to confirm that the output voltage and current are zero. Then press the circuit stop button. Then, disconnect the main power switch of the test bench. Wait until all power indicator lights on the panel are completely extinguished and the circuit is completely de-energized before removing the test cables and grounding wires in sequence to complete the entire operation.
(5) Core Safety Precautions
1. Throughout the process, it is strictly prohibited to connect or disconnect wires while the equipment is powered on. All cable connections, removals, and adjustments must be carried out after the equipment is completely powered off and the circuit has no residual voltage.
2. The operation of adjustable power sources must strictly follow the standardized principle of “zero position start, slow voltage increase, zero position stop”, and no illegal operations are allowed.
3. Regularly conduct equipment maintenance and inspection to focus on checking the internal insulation resistance, grounding continuity, and promptly identify and eliminate potential hazards such as aging lines, insulation damage, and poor contact to ensure that the equipment is in a safe and compliant operating state for a long time.
Four. Core Points for Equipment Selection
When purchasing an on-load test bench for high and low voltage switch cabinets, it is necessary to combine the on-site testing conditions and the parameters of the tested equipment, and carefully check the following core indicators to ensure the compatibility and practicality of the equipment:
(1) Input Power Compatibility
Confirm that the standard input specification of the equipment is three-phase four-wire 380V/50Hz industrial power supply. At the same time, check the power supply capacity at the work site and the load carrying capacity to ensure that it can meet the requirements for full-load operation of the test bench and avoid power shortage causing equipment tripping and unstable parameters.
(2) Output Parameter Coverage
1. Voltage Level: Verify that the fixed and adjustable output of AC needs to cover the conventional working conditions of 220V and 380V, and the DC output needs to cover common voltage levels such as 24V, 48V, 110V, and 220V, to meet the testing requirements of various high and low voltage switch cabinet secondary circuits.
2. Current Capacity: Based on the test thresholds of current relays, overload protection devices, etc. of the tested equipment, confirm that the maximum adjustable current output can meet the on-site calibration conditions, and the mainstream specifications are 10A and 20A. 3. Total machine power: Based on the total power demand for simultaneous operation of multiple outputs, match the rated capacity of the equipment. The commonly used rated capacity is 10kVA or 15kVA to avoid overloading.
(III) Measuring accuracy of instruments
The panel voltage and current meters of the equipment are standardly equipped with accuracy of 1.5 grade or above, which can meet the requirements of routine on-off tests and basic parameter detection. If precise action value verification and high-precision parameter calibration operations are required, additional high-precision portable calibration instruments can be equipped to use professional portable equipment data as the precise judgment basis, without relying on the basic panel meters of the equipment.
(IV) Structure and portability performance
The equipment should be compatible with the mobile operation requirements in various scenarios such as workshops and construction sites. Standardly equipped with load-bearing casters and anti-slip operation handles. The overall size of the regular machine is approximately 550×660×1000mm, with a weight range of 45-75kg. It is lightweight and easy to move, and can be adapted to the transportation and use in narrow operation spaces.
(V) Safety protection configuration
The equipment must be equipped with complete safety protection mechanisms, including basic functions such as multiple circuit output electrical interlock, zero position start protection, overload protection, and short circuit protection, to fully avoid equipment failures and safety accidents caused by operational errors or abnormal loads, and ensure the stable operation of the work.
Post time: May-27-2026