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High power motor over-voltage protection device

A protection device and overvoltage technology, applied in the direction of emergency protection circuit devices, electrical components, etc., can solve problems such as fatigue damage, motor, electric arc furnace transformer damage, loss of vacuum switch, motor and transformer protection, etc.

Inactive Publication Date: 2009-04-29
SHANXI TAIGANG STAINLESS STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] With the development of the metallurgical industry, especially the development of iron and steel enterprises, the power of air compressors and electric furnaces is increasing, and the capacity of the corresponding motors and transformers that supply power to electric arc furnaces is increasing, generally reaching more than 6000kVA. Air compressors The motor of the electric arc furnace is frequently interrupted. The transformer that supplies power to the electric arc furnace is cut off 18-36 times a day without load. No-load current is easy to generate current-carrying overvoltage, which has been accumulated for many years. During the operation, the voltage affects the insulation of the motor and transformer, resulting in damage to the motor and electric arc furnace transformer. For example, the applicant had 6 electric arc furnace transformers in 1987. Due to the voltage The overvoltage electric arc furnace transformer was damaged 20 times, of which the winding and porcelain bottle were damaged 11 times, and the overvoltage damage rate reached 55%. Due to overvoltage, the cable connecting the transformer and the electric arc furnace also exploded many times. 8 motors were also damaged due to voltage overvoltage
In order to prevent the vacuum switch from cutting off the no-load current to generate overvoltage, a zinc oxide arrester is connected in parallel between the three-phase vacuum switch and the transformer as an overvoltage protection device for the electric arc furnace voltage. The zinc oxide arrester is a nonlinear element. Its resistance is very large, but when overvoltage occurs, the resistance value presented is very small. Although the current is released from the ground when the vacuum switch cuts off the no-load current to generate overvoltage, the power grid releases energy to the ground to protect the vacuum switch and the motor. 1. The transformer avoids overvoltage damage, but due to the frequent opening and closing of the vacuum switch, the zinc oxide arrester was frequently switched on and off before the modification. For a 4000kW electric arc furnace power supply equipment, the zinc oxide arrester was switched on and off 20 times a year, and the zinc oxide arrester was quickly fatigued. Damage, loss of protection for vacuum switches, motors and transformers, the damage rate of motors and transformers reaches 50%

Method used

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  • High power motor over-voltage protection device

Examples

Experimental program
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Effect test

Embodiment 1

[0029] The high-power motor overvoltage protection devices described in Fig. 1, Fig. 2 and Fig. 3 include zinc oxide arrester F1, zinc oxide arrester F2 and zinc oxide arrester F3. The negative poles of the three zinc oxide arresters are connected to the terminal XE for grounding. The zinc oxide arrester F1, the zinc oxide arrester F2, and the zinc oxide arrester F3 are connected with the terminal X1, the terminal X2, and the terminal X3 with wires such as the wire 9 for the positive electrode, and the feature is that there are also three-phase electric corresponding Three groups of resistors and capacitors in series R—C resistance capacitors, take R3—C3 resistance capacitors as an example to illustrate the connection of R—C resistance capacitors, the negative pole of capacitor C3 is connected to terminal XE, the positive pole of capacitor C3 is connected to the terminal XE of resistor R3 One end is connected, the other end of the resistor R3 is connected to one end of the fuse...

Embodiment 2

[0034] The circuit diagram of this embodiment and the connection entity diagram of the corresponding electrical components are shown in Fig. 1 and Fig. 2. The rated voltage of power supply in this embodiment is 12KV, and the rated capacitance of capacitor C1, capacitor C2 and capacitor C3 are all 0.10μF±10%. , the rated resistance values ​​of resistor R1, resistor R2 and resistor R3 are all 100Ω±10%, and the technical parameters of zinc oxide arrester F1, zinc oxide arrester F2, and zinc oxide arrester F3 are the second row in Table 2 ( System rated voltage is 10KV).

[0035] This embodiment can be used as a configuration device for a high-power electric arc furnace power supply transformer. The connection with the transformer T and the air switch Q1 is shown in Figure 4 and Figure 5. The rated capacity of the air switch is 800-1250A, and the rated capacity of the transformer T is 5500-6000KVA .

[0036] Present embodiment also can be used as the configuration equipment of hi...

Embodiment 3

[0038] The circuit diagram of this embodiment and the connection entity diagram of the corresponding electrical components are shown in Fig. 1 and Fig. 2. The rated voltage of the power supply in this embodiment is 40.5KV. The rated capacitance of capacitor C1, capacitor C2 and capacitor C3 is 0.05μF±10%. , the rated resistance values ​​of resistor R1, resistor R2 and resistor R3 are all 100Ω±10%, and the technical parameters of zinc oxide arrester F1, zinc oxide arrester F2, and zinc oxide arrester F3 are the fourth line in Table 2 ( The rated voltage of the system is 35KV).

[0039]This embodiment can be used as a configuration device for a high-power electric arc furnace power supply transformer. The connection with the transformer T and the air switch Q1 is shown in Figure 4 and Figure 5. The rated capacity of the air switch is 1000-4000A, and the rated capacity of the transformer T is 40-150MVA . Present embodiment also can be used as the disposition equipment of high-po...

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Abstract

The related over-voltage protector for high-power motor comprises: three ZnO arresters with cathode paralleled together and connected to ground terminal and anode connected to three-phase terminal, three groups of R-C devices with two ends connected to ground terminal and arrester another end respectively. This invention can reduce damage rate of high-power motor and transformer to 2%.

Description

technical field [0001] The invention relates to a high-power motor overvoltage protection device. Background technique [0002] With the development of the metallurgical industry, especially the development of iron and steel enterprises, the power of air compressors and electric furnaces is increasing, and the capacity of the corresponding motors and transformers that supply power to electric arc furnaces is increasing, generally reaching more than 6000kVA. Air compressors The motor of the electric arc furnace is frequently interrupted. The transformer that supplies power to the electric arc furnace is cut off 18-36 times a day without load. No-load current is easy to generate current-carrying overvoltage, which has been accumulated for many years. During the operation, the voltage affects the insulation of the motor and transformer, resulting in damage to the motor and electric arc furnace transformer. For example, the applicant had 6 electric arc furnace transformers in 19...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H7/09
Inventor 陈仁杰
Owner SHANXI TAIGANG STAINLESS STEEL CO LTD