SU1275621A1 - Method of current leakage protection in mine d.c.contact system - Google Patents

Abstract

The invention relates to electrical engineering, in particular, to contact networks from leakage. The purpose of the invention is to improve the electrical safety of contact networks by enabling the control of current leakage through a person, regardless of the presence of consumers in a controlled area of the contact network. The selected harmonic of the variable component of the rectified voltage is filtered and, through a voltage transformer 1, a voltage ripple 4 is applied to the sensor input. The same signal; the variable current component of the current through the transformer then (L with 7ff

Description

ka 3 and the adder 9 feeds into the sensor input zero current pulsations 5. Short pulses from block 5 directly, and from sensor 4 through a single vibrator 6 arrive at the inputs of the COB drop unit 7. When the pulses coincide, the output of block 7 forms a signal including the actuator 8. If the pulses at the input of the Comparison block do not coincide (this corresponds to the appearance of the DC consumer), the signal at the output of block 7 does not occur. In this case, the key 11 is open, and the block 10 generates a compensating signal from the selected voltage harmonics, which leads to the disappearance of the signal at the output of the adder 9. A renewed leakage of current (for example, through a person) causes an increase in the current ripple, which is analyzed without considering earlier compensated ripple -current. This eliminates the influence of the DC consumer circuits on the control of current leakage through a person, i.e., the electrical safety of the contact networks is increased. 2 Il.

The invention relates to electrical engineering, in particular to the field of protection of contact networks against current leakage, and can be used in the development of systems that ensure the safe operating conditions of contact networks of ore and coal mines.

The purpose of the invention is to increase the electrical safety of operation of contact networks by providing the ability to control current leakage through a person regardless of the presence of consumers in a controlled area of the contact network.

- In FIG. 1 shows a functional diagram for the implementation of the proposed method} in FIG. 2 is a voltage chart at the output of the main functional blocks.

The device circuit consists of a voltage transformer connected through separation capacitor 2, a current transformer 3, current and voltage sensors 4 and 5, a single-oscillator 6, a coincidence unit 7, an actuator 8, an adder 9, a unit 10 that produces a delay time compensating signal, key 11 and the element is NOT 12.

The method is carried out as follows.

The selected harmonic of the variable component of the rectified voltage is filtered out and a voltage ripple is applied to the input of the sensor 4 through a voltage transformer. The same harmonic of variable composition.

traction current through the current transformer 3 and the adder 9 is fed to the input of the sensor 5 zero current pulsation. The output of blocks 4 and 5 form short pulses at the moment of transition of the corresponding signal through zero. A pulse from block 4 is fed to the input of the one-shot 6. At the output of the latter, a pulse of a predetermined duration is formed, which is fed to the input of the block 7 of coincidence. The signal from block 5 is also fed to the input of coincidence circuit 7. With the coincidence of the pulses at the input of block 7, at its output a signal is generated including the actuator 8. At the same time, through the element 12, the key 11 blocks the block producing a compensating signal. If the pulses at the input of block 7 do not coincide, which corresponds to the appearance of an unavoidable leakage (direct current consumer), then the signal at the output of block 7 does not occur, the key 11 remains open in block 10. By the magnitude and initial phase of the signal that arrives from key 11 , from the selected voltage harmonics form a compensating signal, which is fed to the second input of the adder 9. The parameters of the compensating signal are selected so that the output signal of the adder is zero. Once again, leakage of current (for example, through a person) causes an increase in the current pulsation and this increment is analyzed without taking into account the previously compensated current ripple, i.e. each again

Claims (1)

20 Formula a 'of the invention A method of protection against current leaks in a DC mine shaft contact network, including the allocation of low-frequency ripple current and voltage in the protected network, measuring the phase shift between the indicated ripple current and voltage, comparing the measured value with a given level and generating a shutdown signal when the specified level is exceeded values, characterized in that, in order to increase the electrical safety of the operation of · contact networks by providing the ability to control current leakage through a person is not The dependence on the presence of customers at the controlled area of the contact system, after the comparison in the case of pre-. increases in the measured level by a phase shift compensate for the ripple * of the current until they disappear completely, and with the subsequent occurrence of ripple current, the indicated operations are performed without taking into account the value of the previously compensated ripple.