AL112 Dielectric loss tester

Implementation of standards.

DL/T962-2005 

The series of equipment, which is mainly used in HV substation engineering project or in test room, gives a precision test on capacity, inductance and dielectric loss of HV capacitive and inductive test object.

1. Main components of the equipment:

HV variable frequency power supply to provide test signal for internal HV test mode

Built-in standard capacitor served as test reference in the mode of inner standard

Digital HV capacitive bridge served as main circuit of sample and measurement

High speed processing unit of digital signal high speed FFT transformation and digital filtering of the sampled signal

Controlling system realizing full-auto intelligent test

Key technology :

Adopt digital frequency technology; application of double frequency 45Hz/55Hz test avoids interference from 50Hz power network, thus making test results of high accuracy possible under interference of 50Hz high electric field in test site.

When in internal HV test mode, keep a track of frequency of power network, in accordance of which frequency of test signal is determined, and at the same time FFT frequency keeps a strict pace with test signal frequency, thus guaranteeing a perfect result in suppression of 50Hz/60Hz power network interference. For the algorithm, it will ensure a throughout elimination of interference from power network, with theoretical residue being 0.

The adoption of synchronous sampling technology presents a simultaneous sampling on two-way of test signals of standard circuit and measuring circuit, greatly improving measuring accuracy of dielectric loss.

Function and index

1. Basic function

Test of dielectric loss of CVT equipment through self-excitation;

Built-in standard capacitor

Grounded connection and ungrounded connection for selection

Three modes of tests for selection, internal HV single-frequency test, internal HV variable frequency test and external HV test;

In an external HV test, keeping track of its frequency which is strictly equal with external HV frequency;

Test procedure: retarded voltage step-up─>measurement─>voltage step- down─>display test result;

Built-in microprinter synchronizes printing of test result and follow-up test;

Through man-machine interface, data of current ambient temperature and humidity are input, which can be saved and printed together with test result;

Grounded protective detection: start ground protection when enclosure charges dangerous voltage due to poor grounding of equipment;

Over current protection: capable of effective quick protection and not causing human danger and equipment damage, when over current emerges from short circuit of test object and test wire touching ground.

2. Main technical index

Capacitive test

Test range: 10pF-63000pF varying from model to model
Test accuracy: ±（reading ×1％＋1pF）
s resolution: 0.01pF

Dielectric loss test

Test range: 0-50％
Test accuracy: ±（reading×1％±0.0004）
resolution: 0.0０1％

Detecting range of current of test object: 31uA-1A

Frequency tracking: range 45Hz-65Hz

Power source of internal HV test: nominal frequency 50Hz, 60Hz

Internal HV output frequency is related to power network owing to application of power network tracking technology.

When setting the test frequency, actual output frequency of internal HV and frequency of power network conform to the following ratio: 90%、100%、110%、120%

For example, when frequency of power network is at 60Hz:

When set at 60 single frequency, actual output frequency is 60×100%=60Hz
When set at 54Hz＼66Hz double frequency, actual output frequency is 60×90%=54Hz and 60×110%=66Hz
Voltage range: 0.5-10kV
Voltage setup: 0.5kV stepping
Voltage displaying range: 0.1-9.99kV
Voltage displaying accuracy: ≤±(1.5％×reading+5V)
Max output current: 200mA
Rated output power: 500W-2000W varying from model to model
Running method: continuous running for ≤15min

Power source of CVT test: auxiliary winding output of power source of internal HV test is used as the power source of CVT test.

Output voltage: ≤50V

Output current: ≤15A

Test voltage: ≤3000V

Power supply:

Voltage: 220V±10%
Frequency: 50Hz±0.5Hz/60Hz±0.6Hz

Ambient condition:

Temperature range: -10℃～55℃
Relative humidity:＜90％

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