CN113471934B - An inverse-time overcurrent protection device for the DC motor circuit of a switch cabinet - Google Patents

Abstract

The invention discloses an inverse time limit overcurrent protection device of a switch cabinet direct current motor loop, which is characterized in that an inverse time limit overcurrent relay is connected in series in the motor loop to monitor the current of the motor loop in real time, when the motor has overcurrent, overload and short circuit stalling, a signal is output through an action contact according to a set time limit and is used for cutting off the power supply loop of the motor, and meanwhile, the signal is sent to a background system for monitoring. The invention realizes the real-time protection of the motor, prevents the motor from being burnt out due to overcurrent stalling, reduces the faults and improves the reliability of the secondary control system. The anti-time-limit overcurrent relay can reliably act according to the preset time limit, send out signals and remove faults when overcurrent, overload and short circuit locked rotor faults occur in the circuit of the switch motor of the electrical equipment during operation, ensure the safe operation of main equipment and a power transmission and distribution system, and greatly improve the economic benefit.

Description

An inverse-time overcurrent protection device for the DC motor circuit of a switch cabinet

technical field

The invention relates to the technical field of electrical equipment, in particular to an inverse-time overcurrent protection device for a DC motor circuit of a switch cabinet.

Background technique

At present, in the indoor metal-enclosed switchgear, the overcurrent protection measures for the operation of the DC motor of the circuit breaker DC energy storage motor, the handcart propulsion mechanism motor, the isolation switch, the grounding switch, and the three-position switch are mainly series miniature circuit breakers. The fault contact, once the motor circuit fails, the fault contact will act to realize the overload protection function. However, the miniature circuit breaker cannot quickly reflect the overcurrent condition of the motor and cut off the operating power of the motor in time according to the overcurrent condition, which causes the motor to be easily damaged due to overcurrent blocking and increases the failure rate of the electrical control loop.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention lies in the operation of the DC energy storage motor, the handcart propulsion mechanism motor, the isolation switch, the grounding switch and the three-position switch in the switchgear. Faults such as short-circuit and locked rotor damage the motor, cause the switch to fail to operate normally, and affect the normal power supply of the switchgear. An inverse-time overcurrent protection device for the DC motor circuit of the switchgear is provided.

In order to realize the above-mentioned purpose of the invention, the technical scheme adopted in the present invention is as follows:

An inverse-time overcurrent protection device for a DC motor circuit of a switch cabinet is characterized in that: an inverse-time overcurrent relay is connected in series in the motor circuit to monitor the current of the motor circuit in real time. At the time, according to the set time limit, the signal is output through the action contact, which is used to cut off the power circuit of the motor, and at the same time send the signal to the background system for monitoring.

In a preferred embodiment of the present invention, it also includes a switch motor, an energy storage power switch, a motor control switch and a communication device, the switch motor, inverse time overcurrent relay, energy storage power switch, motor control switch, and communication device. The switch motor energy storage circuit and the inverse time limit overcurrent signaling circuit, wherein the switch motor energy storage circuit is composed of the energy storage power switch and the switch motor, the motor control switch, the energy storage motor micro switch, and the inverse time limit overcurrent relay. It is composed of a group of action contacts, a series branch after the input coil of the inverse time overcurrent relay is connected in series, and the auxiliary power supply of the inverse time overcurrent relay, wherein the series branch is connected in parallel with the auxiliary power supply of the inverse time overcurrent relay and then connected to the energy storage device. On the power switch, the energy storage power switch is connected to the positive and negative terminals of DC220V; the inverse time overcurrent signaling circuit is composed of the energy storage switch fault contact, the second group of action contacts of the inverse time overcurrent relay, and a communication device, wherein The fault contact point of the energy storage switch and the second group of action contacts of the inverse time limit overcurrent relay are connected in parallel to the two input ends of the communication device.

In a preferred embodiment of the present invention, the inverse-time overcurrent relay operates according to the time limit t _s preset by the formula (1), and the second group of action contacts of the inverse-time overcurrent relay sends a signal to the communication device; At the same time, the fault contact of the energy storage switch transmits the fault signal to the background system through the communication device:

In the formula (1), _{C is the time constant; IR is the real-time input current; IS is} the set current.

In a preferred embodiment of the present invention, the time constant C usually ranges from 0.1 to 9.9, and usually the default value is 1.

The working principle of the present invention is as follows: the present invention monitors the current of the switch motor circuit in real time by connecting the reverse time limit overcurrent relay in series with the switch motor circuit. The output signal through the action contact is used to cut off the power circuit of the switch motor, and at the same time send the signal to the background monitoring. Realize the real-time protection of the motor, prevent the motor from burning out due to over-current blocking, reduce faults, and improve the reliability of the secondary control system.

The invention solves the problem that the electrical equipment switches the motor circuit, when the overcurrent, overload and short-circuit locked-rotor faults occur during operation, the inverse-time overcurrent relay can reliably act according to the predetermined time limit, send a signal, and remove the fault, so as to ensure the main equipment and the transmission and distribution. The safe operation of the electrical system greatly improves the economic benefits.

Description of drawings

FIG. 1 is a schematic diagram of an energy storage circuit of a switching motor according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of an inverse time-limited overcurrent signaling loop according to an embodiment of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

The invention is an inverse-time overcurrent protection device for the DC motor circuit of a switch cabinet. When the short-circuit is blocked, the signal is output through the action contact according to the set time limit, which is used to cut off the power circuit of the motor, and at the same time send the signal to the background system for monitoring.

The specific technical scheme is that the switch motor 11, the inverse time overcurrent relay, the energy storage power switch 13, the motor control switch 14, and the communication device 15 form the switch motor energy storage circuit and the inverse time overcurrent signaling circuit.

Referring to Fig. 1, the switching motor energy storage circuit is composed of the energy storage power switch 13 and the first group of inverse time limit overcurrent relays by the switching motor 11, the motor control switch 14, two aviation plugs CZ 17, the energy storage motor microswitch Sl 16, and the energy storage power switch 13. The action contact 122, the series branch after the inverse time overcurrent relay input coil 12 is connected in series, and the inverse time overcurrent relay auxiliary power supply 121 are composed, wherein the series branch is connected in parallel with the inverse time overcurrent relay auxiliary power supply 121 and then connected to the energy storage power supply On the switch 13, the energy storage power switch 13 is connected to the positive and negative terminals +HM and -HM of DC220V.

Close the energy storage power switch 13 (1DK), the inverse time overcurrent relay auxiliary power supply 121 (KA) is energized, close the motor control switch 14 (HK), the energy storage circuit is energized, the switch motor 11 (M) starts to store energy, and the reverse The current input coil 12 (KA) of the time limit overcurrent relay is put into operation. The inverse time overcurrent relay monitors the current of the circuit of the switch motor 11 in real time. When the switch motor 11 has overcurrent, overload and short-circuit stall faults, the inverse time overcurrent relay (KA) follows the preset time limit ts of formula (1). Reliable action, through the first group of action contacts 122 (KA) of the relay to send out a fault signal to prevent the motor from burning out due to overcurrent blocking, to protect the switch motor in real time, and to ensure the reliability of the secondary circuit.

In the formula (1), _{C is the time constant; IR is the real-time input current; IS is} the set current. The time constant C usually ranges from 0.1 to 9.9, and the default value is usually 1.

Referring to Fig. 2, the inverse time overcurrent signaling circuit is composed of the energy storage switch fault contact 131, the second group of action contacts 123 of the inverse time overcurrent relay and the communication device 15, wherein the energy storage switch fault contact 131, the inverse time overcurrent relay The second group of action contacts 123 are connected in parallel to the two input ends of the communication device 15 .

The inverse-time overcurrent relay KA operates according to the time limit ts preset by the formula (1), and sends a signal to the communication device 15 (smart communication screen) through the second group of action contacts 122 (KA) of the relay. At the same time, the fault contact 131 (1DK) of the energy storage power switch transmits the fault signal to the background system through the communication device 15 (smart communication screen). Provide guarantee for the safe operation of main equipment and transmission and distribution systems.

In the operation of the DC energy storage motor of the circuit breaker, the motor of the handcart propulsion mechanism, the isolation switch, the grounding switch, and the three-position switch, the DC motor circuit is connected in series with a reverse-time overcurrent relay to protect the motor in real time and ensure the reliable operation of the power grid. Improve social and economic benefits.

The basic principles and main features of the invention and the advantages of the invention have been shown and described above. Those skilled in the art should understand that the present invention is not limited by the above-mentioned embodiments. The above-mentioned embodiments and descriptions only illustrate the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will also have Various changes and improvements fall within the scope of the claimed invention, which is defined by the appended claims and their equivalents.

Claims (3)

1. an inverse time limit overcurrent protection device of a DC motor circuit of a switch cabinet, it is characterized in that: connect inverse time limit overcurrent relay in series in the motor circuit, monitor the current of the motor circuit in real time, when the motor occurs overcurrent, overload, short circuit When the rotor is blocked, the signal is output through the action contact according to the set time limit, which is used to cut off the power circuit of the motor, and at the same time send the signal to the background system for monitoring; It also includes a switch motor, an energy storage power switch, a motor control switch and a communication device. The switch motor, inverse time overcurrent relay, energy storage power switch, motor control switch, and communication device form a switch motor energy storage circuit and an inverse time overcurrent. A signaling circuit, wherein the switch motor energy storage circuit consists of an energy storage power switch and a switch motor, a motor control switch, an energy storage motor micro switch, a first group of action contacts of an inverse time limit overcurrent relay, and an inverse time limit overcurrent relay. The series branch after the input coil is connected in series and the auxiliary power supply of the inverse-time overcurrent relay, wherein the series branch and the auxiliary power supply of the inverse-time overcurrent relay are connected in parallel to the energy storage power switch, and the energy storage power switch Connect the positive and negative terminals of DC220V; the inverse time overcurrent signaling circuit is composed of the energy storage switch fault contact, the second group of action contacts of the inverse time overcurrent relay and the communication device, wherein the energy storage switch fault contact, inverse time overcurrent The second group of action contacts of the relay are connected in parallel to the two input ends of the communication device. 2. The inverse-time overcurrent protection device for a DC motor circuit of a switch cabinet according to claim 1, wherein the inverse-time overcurrent relay acts according to the time limit t _s preset by the formula (1), and the reverse The second group of action contacts of the time-limited overcurrent relay sends a signal to the communication device; at the same time, the fault contact of the energy storage switch transmits a fault signal to the background system through the communication device:

In the formula (1), C is the time constant; I _n is the real-time input current; I _s is the set current. 3 . The inverse-time overcurrent protection device for the DC motor circuit of a switch cabinet according to claim 2 , wherein the value range of the time constant C is 0.1 to 9.9. 4 .

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