QLDJS-EA (FA) Dielectric Loss Tester

Safety Measures

1. The operator of the instrument should have a general understanding of the use of electrical equipment or instruments.
2. This instrument can be used both indoors and outdoors, but it should be kept away from places where it may be exposed to rain, corrosive gases, excessive dust, high temperatures, or direct sunlight.
3. The instrument should be kept away from severe vibration.
4. The maintenance, care and adjustment of the instrument should be carried out by professionals.
5. Before any wiring, the grounding terminal of the instrument must be reliably connected to the earth with a grounding cable.
6. As the testing equipment generates high voltage, the testers must strictly follow the safety operation procedures to prevent others from touching the high-voltage components and circuits. Personnel directly engaged in the test must have a thorough understanding of the high-voltage test circuit and the key points of instrument operation. Non-testing personnel must stay away from the high-voltage testing area. The testing area must be clearly marked with fences, ropes, warning signs, etc.
7.  The adjustment, repair and maintenance of the instrument must be carried out without power on. If power must be on, the operator must be very familiar with the high-voltage hazardous components of this instrument.
8. When the fuse is damaged, it is essential to ensure that the same type of fuse is replaced. It is strictly prohibited to replace fuses of different models or directly short-circuit the fuse for use.
9. When the instrument malfunctions, turn off the power switch and wait for one minute before checking again.

Performance Characteristics

1. The instrument adopts Fourier transform digital filtering technology to measure capacitance, dielectric loss and other parameters. The test results are highly accurate and convenient for achieving automated measurement.
2. The instrument adopts frequency conversion technology to eliminate the 50Hz power frequency interference on site, and can measure reliable data even in an environment with strong electromagnetic interference.
3. It adopts a full-touch large LCD display, which is easy to operate. The full touch LCD screen and the super-large full graphic operation interface enable operators to use it without additional professional training. The entire measurement process can be completed with just a gentle touch.
4. Data storage: Equipped with a calendar chip and a large-capacity memory internally, it can save the test results at any time. Historical records can be viewed at any time and printed out. Both the current time and the storage time can be displayed and printed at any time.
5. Scientific and advanced data management: Instrument data can be exported via a USB flash drive and viewed and managed on any PC through dedicated software.
6. The instrument is easy to operate. The measurement process is controlled by a microprocessor. As long as the appropriate measurement method is selected, the data measurement can be automatically completed under the control of the microprocessor.
7. Integrated model, equipped with standard capacitors and high-voltage power supply, facilitating on-site testing and reducing on-site wiring.
8. The instrument has a high measurement accuracy and can meet the requirements of oil dielectric loss measurement. It only needs to be equipped with a standard oil cup to achieve oil dielectric loss measurement.
9.  It has the function of reverse connection low-voltage shielding. Under the condition that the 220kV CVT busbar is grounded, the dielectric loss of C11 can be measured in reverse connection at 10kV without disassembling the wires
10.  It is capable of conducting AC withstand voltage tests. It is convenient for the secondary AC withstand voltage test of PT and CT, and for the withstand voltage test of 400V low-voltage system.
11. It can identify the frequency of external high-voltage power supply ranging from 40Hz to 70Hz, allowing for large-capacity high-voltage dielectric loss tests using industrial frequency power supply or series resonant power supply.
12. It has the CVT testing function and can realize the self-excitation method test of CVT. Four protection limits, namely high-voltage voltage/current and low-voltage voltage/current, can be set to ensure the safety of personnel and equipment.
    When testing CVT, it can not only automatically test the capacitance and dielectric loss values of C1 and C2, but also test the total capacitance and dielectric loss values of the CVT equipment.
13. It is equipped with a thermal printer for print output, a calendar clock, which is convenient for users to generate test reports, and a USB flash drive for output.
14. With a computer interface. One computer can control 32 instruments and can be integrated into a comprehensive high-voltage test vehicle to achieve measurement, data processing and report output.
15. Grounding protection function: When the instrument is not grounded or poorly grounded, it will not enter the normal program and will not output high voltage. The overcurrent protection function ensures that the instrument is not damaged when the test sample is short-circuited or broken down.
16. Electric shock protection function: When the operator of the instrument accidentally gets an electric shock, the instrument will immediately cut off the high voltage to ensure the safety of the test personnel.
17. Comply with the State Grid’s technical specifications for data and communication of digital test instruments for electrical equipment. Built-in Bluetooth communication. (Optional)

Technical Indicators

Accuracy: Cx: ± (reading ×1%+1pF)
tgδ: ± (reading ×1%+0.00040)
Anti-interference index: Variable frequency anti-interference, it can still achieve the above-mentioned accuracy under 200% interference
Capacitance range: Internal high voltage application: 3pF to 6000pF /10kV, 60pF to 1.5μF/0.5kV
External high voltage: 3pF to 1.5μF/10kV, 60pF to 30μF/0.5kV
Resolution: Up to 0.001pF, 4 significant figures
tgδ range: unlimited, resolution 0.001%, automatic recognition of three types of test samples: capacitance, inductance and resistance.
Test current range: 5μA to 5A
Internal high voltage application: Set voltage range: 0.5 to 10kV, maximum output current: 200mA
Voltage rise and fall mode: The voltage can be set freely. For example, 5123V.
Test frequency: 40-70Hz, single frequency can be set freely. For example, 48.7Hz.
The automatic dual frequency conversion can be set freely from 50±0.1Hz to 50±10Hz.
The automatic dual frequency conversion can be set freely from 60±0.1Hz to 60±10Hz.
Frequency accuracy: ±0.01Hz
External high voltage: The maximum test current when connected in positive direction is 5A, and it is 40-70Hz at power frequency or variable frequency
When connected in reverse, the maximum test current is 10kV/5A, with a power frequency or variable frequency range of 40-70Hz
Low-voltage output of CVT self-excitation method: Output voltage 3 to 50V, output current 3 to 30A.
Measurement time: approximately 40 seconds, which is related to the measurement method
Input power supply: 180V to 270VAC, 50Hz±1%, powered by mains electricity or generator
Computer interface: Standard RS232 interface, USB flash drive port (automatic USB flash drive data storage).
Printer: Micro thermal printer. Ambient temperature: -10℃ to 50℃. Relative humidity: <90%
Dimensions: 500mm*377mm*330mm Instrument weight: 28kg

Measurement methods and principles

There are two measurement methods based on whether the test subject is grounded, namely the positive connection measurement method and the reverse connection measurement method. The principles of the two measurement methods are shown in Figure 1:

On the 10kV side of the high-voltage power supply, the high voltage is divided into two paths. One path is supplied to the standard capacitor CN inside the machine. The dielectric loss of this capacitor is very small and can be regarded as zero, which is a pure capacitive current. This current ICN can be used as the reference for capacitive current. On the side of the Cx sample, the sample current Icx is drawn into the machine through the sampling resistor R. This Icx can be decomposed into horizontal and vertical components as shown in Figure 2. The tgδ value can be obtained by calculating the ratio of the horizontal component to the vertical component.

In Figure 1 (a), Cx is a non-grounded test sample, and the test sample current Icx enters the sampling resistor R from the end of the test sample to obtain the full current value. In Figure 1 (b), Cx is a grounded test sample, and the Cx end inside the machine is directly grounded. The current Icx enters the sampling resistor inside the machine from the high-voltage end of the test sample to obtain the full current value.

Instrument Function Introduction —- The instrument panel is shown in Figure 3 below:

1. C_N socket – It is the measurement input terminal for the external standard capacitor signal. When using the internal standard, this terminal is left suspended.
2. C_Xsocket – It is the measurement input terminal for the test sample signal. When connected in the correct direction, it is connected by a dedicated low-voltage cable. This cable is single-layer shielded with a specially made alligator clip, 8 meters long, and is connected to the lower end of the test sample. When connected in reverse, this end is left empty.
3.  RS232 interface – used to connect to a computer, control the instrument and upload data.
4. Usb flash drive port – used for exporting data stored in the instrument.
5.  Printer – Prints measurement data.
6.  Color touch screen display -640*480 resolution, controls and displays menus, various prompt information and measurement results.
7.  Self-excitation current output terminal – a dedicated terminal for measuring CVT, usually connected to the auxiliary winding da.
8.  Self-excited current output terminal – a dedicated terminal for measuring CVT, usually connected to the auxiliary winding dn.
9.  Grounding terminal – It is the terminal for grounding wire connection.
10. High-voltage switch – responsible for starting and stopping the high-voltage power supply inside the instrument.
11. Power socket – AC 220V±10%, 50±1Hz power input port, with 5A fuse.
12. Power switch – for turning on and off the power of the entire machine.
13. High-voltage wiring diagram on the side of the instrument

High-voltage line HV socket, high-voltage line grounded shielded socket (already grounded inside, just plug it in)

The small black clip is a high-voltage shield and is generally suspended (with high voltage).  Connect the large red clip to the high-voltage part under test