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XDDZ transformer neutral point resistance current limiting complete device
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  • XDDZ transformer neutral point resistance current limiting complete device

XDDZ transformer neutral point resistance current limiting complete device

1. Product Overview The transformer neutral point resistance current limiting device (hereinafter referred to as the device) is composed of a high-power resistor and a graphite discharge gap in parallel, and is installed between the neutral point of the transformer of 110KV and above and the ground. The device mainly aims to suppress the DC bias of the transformer by increasing the loop resistance and limiting the DC current flowing through the transformer winding. When the AC grounding fault occurs in the AC system, once the neutral point voltage of the transformer exceeds the threshold value of the discharge gap, the discharge gap is instantaneously broken down to ensure reliable grounding of the neutral point of the transformer and protect the current limiting resistor. The device can be widely used to solve the single-maximal return line operation of the HVDC transmission system, and the DC bias problem caused by the urban rail transit stray current and other main AC main transformers, and ensure the safe operation of the power grid.

Category: Product Center

Key words: equipment


Product Description

1. Product Overview
The transformer neutral point resistance current limiting device (hereinafter referred to as the device) is composed of a high-power resistor and a graphite discharge gap in parallel, and is installed between the neutral point of the transformer of 110KV and above and the ground. The device mainly aims to suppress the DC bias of the transformer by increasing the loop resistance and limiting the DC current flowing through the transformer winding. When the AC grounding fault occurs in the AC system, once the neutral point voltage of the transformer exceeds the threshold value of the discharge gap, the discharge gap is instantaneously broken down to ensure reliable grounding of the neutral point of the transformer and protect the current limiting resistor. The device can be widely used to solve the single-maximal return line operation of the HVDC transmission system, and the DC bias problem caused by the urban rail transit stray current and other main AC main transformers, and ensure the safe operation of the power grid.
2, system structure
The device consists of a resistor, a graphite gap and a Hall current sensor, and is capable of displaying the real-time current flowing through the resistor in the field.
XDDZ transformer neutral point resistance current limiting complete device
3. Technical parameters
Name Unit Performance parameter
Rated resistance Ω See product model
Resistance deviation range at 25℃ ± 5%
Adjustable range of resistance Ω 0.5~rating
Adjustable resistance difference Ω 0.5
Temperature coefficient of resistance Ω/℃ ≦5.6×10-4
Dynamic steady current kA/0.2s(peak) 25
Thermally stable current kA/1s(effective value) 10
Thermally stable temperature rise limit (10kA/1s)K <760
Long working current A(effective value) 100
Long-term temperature rise limit (100A/4h)K <385
Rated power frequency withstand voltage kV/60s(effective value) 95
Rated lightning impulse withstand voltage kV(peak) 185
Absolute resistance to ground 2500
Graphite gap flow capacity kV/1s(effective value) 10
Graphite power frequency breakdown voltage kV(effective value) 3~5
Box size (length * width * height) mm*mm*mm 3600*2200*2800
Total weight of the complete set Kg 3500
4. Technical characteristics
1.XDGZ series current limiting resistor device has small size, compact structure, convenient operation and maintenance, and is suitable for indoor and outdoor installations of substations and outdoor occasions.
2. The resistor is made of stainless steel resistor, which has low temperature coefficient of resistance, high temperature resistance, corrosion resistance and high mechanical strength.
3. The device resistance can withstand 1400 ° C high temperature, and fireproof and explosion-proof, stable resistance.
4. The device can monitor the DC and AC current flowing through the resistor, and has real-time display function on site. It has a field communication bus, which can transmit the monitoring data to the substation monitoring center.
5, monitoring unit description
The device is equipped with two sets of Hall current sensors with 50A and 2000A ranges, which can monitor the neutral and DC currents of the transformer in real time. Open the monitoring unit door of the unit at the site to view real-time data. The meanings of the display in the display interface are:
Idc: neutral point DC (50A sensor measurement data);
Iac: neutral point communication (50A sensor measurement data);
Im: neutral point communication (2000A sensor measurement data, showing large current values);
Num: The number of neutral point overcurrents (existed as an overcurrent when the AC current is greater than 100A).
The real-time values ​​of Idc, Iac, and Im displayed by the monitoring unit can be transmitted to the substation monitoring system through the 485 communication port.
The monitoring unit has three hard node open terminals, which are defined as follows
Name Meaning
Device power failure alarm Monitoring unit loses working power
DC over-limit alarm Neutral point DC exceeds 10A
AC limit alarm Neutral point communication exceeds 100A