Influence of Vacuum Tube Failure in Underground Vacuum Starter on Leakage Relay Ma Jun (Pangzhuang Coal Mine, Xuzhou Mining Group Co., Ltd., Xuzhou 221141, Jiangsu, China) respectively introduced the leakage protection functions and working principles of vacuum starter JDB and JY82 leakage relays according to the actual conditions on site. The situation described three kinds of abnormal phenomena generated by a leakage relay (abbreviated as a leak detector) when a vacuum starter fails, and the theoretical analysis of the root cause of the above phenomenon was analyzed in detail.
Vacuum Tube; Leakage Blockage; Detecting Current; Superposition Principle 1 Advantages and Common Faults of Vacuum Starter 11 Advantages of Vacuum Starter Vacuum starter has the advantages of strong breaking capacity, small mechanical vibration, complete protection function, and high safety performance. Therefore, it is widely used in low-voltage power supply systems in coal mines.
12 Common Faults of Vacuum Starter Due to improper use, low quality of maintenance personnel, and some product quality problems, vacuum starters inevitably have various types of failures, which mainly include the following types: poor contact or over-position of the reversing switch, resulting in a switch Single-phase or unable to stop electricity; the contact switch of the trip switch breaks, causing the switch to start difficult or insecure; the vacuum contactor mechanism is blocked or the nested spring is jammed to cause the vacuum tube to break off slowly; the vacuum tube closed cap looses or the vacuum tube leaks coal to cause damage The switch is charged on the load side.
2 Vacuum starter JDB leakage lockout working principle JDB is a motor integrated protection device, it has overload, phase failure, line, leakage lock and other protection functions.
JDB leakage blocking schematic diagram When the motor and its power supply circuit is highly resistive, the leakage current of the power supply Ec flowing out through R, R2 is small, A, B two points in the high-power BG1 is still in the conduction state, the relay J is engaged Allow starter to start.
When the leakage resistance is less than the blocking value, the current flowing through R1, R2 increases, the level between A, B drops, N14 reverses, and C becomes a low level, D! Conduction, BG1 cut off, J no electricity release, its normally open contacts open, does not allow the starter to start.
3JY82 leakage relay working principle The basic circuit composition is as shown.
JY82 leakage relay schematic diagram DC power supply E1 (provided by ZL) in the ZJ formation detection current = EW (R +2 r) leakage resistance, 660V system design value is 11kH; 2r is the sum of the resistance of all components of the entire DC detection circuit except R, Mainly depends on the internal resistance of ZJ, generally 1kH. / (11 +1) = 5mA detection current path is: ZL (ten) * kH + R * Grid - under normal circumstances, R value is relatively large (60kH ~ 300kH) detection When the current is less than 5mA, ZJ does not operate and the feed switch does not trip. When a leakage fault occurs, R decreases, the leveling state flowing through ZJ, the output power/AC point is high, and the SeDt turn-off current is greater than the current, and the WriJ pull-in M-hTQ pull-in feed net switch trips. Achieve leakage protection.
The role of JY82 leakage relay: monitoring the insulation status of the line; realizing reliable leakage protection; able to properly compensate the grid capacity current.
4 Influence of the vacuum starter vacuum conduction on the JY82 leakage relay 41 After the fault occurred, the phenomenon of the JY82 leakage relay occurred. According to the experience in the field, it was found that the abnormal operation of the leakage relay is closely related to the failure of the vacuum tube, and with various types of starters. Different models and different, generally there will be the following phenomena: leakage relays immediately action, feed open and trip, line resistance monitoring value was significantly reduced (usually 14 21kQ), leakage relay does not move, but the test is normal.
The ohmmeter is reverse biased, and the leakage relay does not act before and after the test.
42 Analysis of the reasons 4.2.1 After the vacuum tube conduction on the protection circuit When a certain vacuum tube is turned on, combined with a vacuum tube in the composite figure after conduction, Ec is JDB DC supply voltage Ec = +15V; * The phase voltage of the three-phase reactor is U*=380V; d is the DC voltage after Usk is rectified by the diode; Ei is the DC detection power, Ei =60V; Xl is the inductive reactance of the zero-sequence reactor SK, Xl=100lAft, R2 is the current limiting resistance of the leakage branch (in the electronic card), and the dotted line in R represents the path formed by the connected vacuum tube, the power grid, and the auxiliary contacts of the switch.
4.2.2 Computation and analysis are generated by the same action. Using the principle of superposition, there is the existence of Xl in the circuit, and Ud is calculated according to the theory of “AC current conversion technologyâ€. 180* is determined by the following equation: Equation (3) is the transcendental function For different people, the corresponding zero and related Ud values ​​can be obtained by using the trial method, as shown in Table 1 (ft is taken as three commonly used resistance values).
Substituting (1) for >5mA at this time, the leak detector immediately operates to verify the phenomenon (1).
5mA, at this time the detector does not move, because there is a current through the ZJ, the same current in the ohmmeter, so that the absolute resistance monitoring value decreases to verify the phenomenon (2).
The protection component, Ec=40V, and the polarity of the power supply is opposite to the polarity of the JDB leakage blocking part. It forms the reverse current of the detection loop with Ud by the balance resistance Rp of ZL, that is, the phenomenon (3) occurs. The output voltage E1 of ZL is cut off by the GD on the leakage protection component in DQZBH-300/1140 and will not be discussed here.
Learned from the underground mine site, 80 series vacuum switch vacuum tube conduction, the leakage relay can generally move, for the 120,225 series switch in the case of action is less, only 300 series switch to appear ohmic reverse phenomenon .
At the Beijing Coal Management Cadre Institute, he is currently working in the Electromechanical Zone 3 of the Pangzhuang Coal Mine in Xuzhou Mining Group.
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