Introduction to troubleshooting methods for the two major faults of series resonance (also known as variable frequency series resonance device)

The device that acts on the series resonance frequency is applied to the power system or power preventive testing project. When high-frequency insulation (insulation) is used for the inspection of large capacity electrical devices, the electrical pressure testing device is realized by changing the frequency characteristics of the device that acts on the series resonance frequency. The series resonance frequency of the device has not been increased before, and the method of using a DC high voltage generator with electrical insulation reliability for applying DC high voltage to the measuring equipment is used. Variable frequency series resonance can be widely used for on-site verification of capacitive voltage and current transformers of 500kV and below in China. Variable frequency series resonance is a dry-type combination series resonance device composed of an excitation transformer (pressure variable) and multiple resonant reactors. Single component units have small volume and light weight Specially suitable for field operations and protection functions, including protected zero (when the voltage output control knob (handle) is not zero, the blocking system is activated), overvoltage protection, overcurrent protection, flashover protection functions, ensuring a reliable system.

How to troubleshoot common faults of variable frequency series resonant devices? Variable frequency series resonant devices are commonly used for AC withstand voltage testing of high-voltage power equipment such as power cables. They have the characteristics of fast testing speed, high accuracy, and safe use. At the same time, they are small in size and are very popular among power workers. However, sometimes due to improper use or equipment reasons, some faults may occur. Taking the variable frequency series resonant device as an example, let me briefly introduce how to troubleshoot common faults of the variable frequency series resonant device.

1、 Fan cannot start:

1. After emergency stop, fault protection, and out of tune protection, the "fault system reset" was not pressed;

2. Internal temperature too high, thermal protection for power components;

Remedial measure: Turn off the power supply of the instrument with series resonance frequency, leave the instrument for about 30 minutes, and then turn on the power supply of the variable frequency series according to the "reset" button on the magnetic resonance instrument panel, and then start the instrument.

If the fan still cannot be started, please contact the frequency converter series resonance manufacturer. The instrument cannot be disassembled!

2、 Automatic tuning cannot be completed, resonance point cannot be found:

Phenomenon: The tuning curve is completely a straight line, and the instrument indicates that there is no resonance point after tuning is completed

Reason: Poor grounding of the circuit, incorrect wiring of the test circuit, and an open circuit in one of the instruments of the variable frequency series resonant device

Exclusion method:

1. Check the reliable grounding of the device and connect the grounding cable to the cutting point;

2. Inspect the on/off status of the high and low voltage coils of the excitation transformer (pressure controlled variable); (The resistance of the low-voltage primary winding is determined by the resistance value; the resistance value of the high-voltage working winding is determined by the output terminal of each student to the high-voltage tail.)

3. Only conduct electrical inspections on the discharge from each reactor; (Resistance of each winding)

4. Check the continuity of the signal line of the voltage divider; (High and low voltage cause capacitance)

5. Inspect the on-off state of the high and low voltage capacitor arms of the voltage divider in the frequency converter series resonant device; (1 hole to core, 2 holes to shell are respectively conductive; 1 hole to 2 holes are disconnected)

6. When the variable frequency series resonator device itself is boosted, there is no resonance point, and it is also necessary to check the on/off status of the compensation capacitor