I. Overview

MOEORW-4700DAbnormal frequency dielectric loss testerIt is a high-precision testing instrument used for testing the dielectric tangent and capacitance of various high-voltage power equipment on site or in laboratories, such as power plants and substations. The instrument is an integrated structure with a built-in dielectric loss testing bridge, a variable frequency voltage regulating power supply, a step-up transformer, and SF₆ High stability standard capacitor. The high-voltage source for testing is generated by the inverter inside the instrument and is used for testing the test sample after being stepped up by a transformer. The frequency can be changed to50.0Hz、47.5Hz\\52.5Hz、45.0Hz\\55.0Hz、60.0Hz、57.5Hz\\62.5Hz、55.0Hz\\65.0Hz， By using digital notch technology, the interference of power frequency electric fields on testing is avoided, fundamentally solving the problem of accurate measurement under strong electric field interference. It is also applicable to situations where a generator is used for power supply testing after a complete power outage. This instrument is equipped with an insulating oil cup and a temperature control device to test the dielectric loss of insulating oil.

Abnormal frequency dielectric loss testerIt mainly has the following characteristics:

lLarge LCD Chinese display

Easy to operate, the instrument is equipped with a full touch LCD display screen and a super comprehensive touch operation interface. Each process is very clear and understandable, and operators do not need additional professional training to use it. With just a gentle click, the entire measurement process can be completed, making it an ideal intelligent dielectric loss measurement device at present.

lMassive storage of data

The instrument is equipped with a calendar chip and a large capacity memory to store data inside200 sets, able to save test results in chronological order, view historical records at any time, and print and output.

lScientific and excellent data management

Instrument data can be obtained throughUSB drive export allows you to view and manage data on any PC.

lMultiple testing modes

The instrument can be tested using various methods such as internal high voltage, external high voltage, internal standard, external standard, positive connection method, reverse connection method, self-excited method, etc; Under high voltage conditions outside the standard, high voltage (greater than) can be applied10kV) dielectric loss.

lCVT testing in one step

This instrument can also test fully sealedThe dielectric loss and capacitance of CVT (Capacitive Voltage Transformer) C1 and C2 have been tested simultaneously. This instrument can also test the CVT ratio and voltage angle difference.

lMeasurement without dismantling the high-voltage lead wireCVT

The instrument can be used without dismantlingAccurately measure the dielectric loss and capacitance values of the CVT under high voltage lead conditions.

lMeasurement of C0 using CVT reverse shielding method

The instrument can be measured using reverse shielding methodThe dielectric loss value and capacitance value of C0 at the upper end of CVT.

lHigh speed sampling signal

The inverters and sampling circuits inside the instrument are all digitally controlled, and the output voltage is continuously adjustable.

lLCR fully automatic measurement

Fully automatic measurement of inductance, capacitance, and resistance, with angle display.

lSimultaneous testing of four channels

When using the positive connection method to test wiring, the total capacitance of the four test samples should not exceed the maximum capacitance value that can be tested by a single test sample, and it is possible to test the dielectric loss values of all four test samples simultaneously.

lMultiple protection, secure and reliable

The instrument is equipped with multiple protection measures such as input voltage fluctuation, high voltage current, output short circuit, power failure, overvoltage, overcurrent, temperature, etc., ensuring the safety and reliability of the instrument. The instrument also has a grounding detection function to ensure that ungrounded equipment is not allowed to operate and start testing.

2、 Working principle

Under the action of AC voltage, the dielectric consumes some electrical energy, which will be converted into thermal energy and result in losses. This type of energy loss is called dielectric loss. When an alternating voltage is applied to a dielectric, there is a phase difference between the voltage and current in the dielectricψ. The remainder angle δ of ψ is called the dielectric loss angle, and the tangent tg δ of δ is called the dielectric loss angle tangent. The TG δ value is a parameter used to measure the dielectric loss. The instrument measurement circuit includes a standard circuit (Cn) and a test circuit (Cx), as shown in Figure 2-1. The standard circuit consists of a built-in high stability standard capacitor and a measurement circuit, while the test circuit consists of the test sample and the measurement circuit. The measurement line consists of a sampling resistor, a preamplifier, and an A/D converter. By measuring the amplitude and phase difference of the standard circuit current and the tested circuit current through the measurement circuit, the capacitance value and dielectric loss tangent value of the test sample are obtained through vector operation using a digital real-time acquisition method by a digital signal processor. The instrument has adopted anti-interference measures internally to ensure accurate measurement under external electric field interference.

3、 Main technical parameters