Soft starting device multi-split motor magnetic balance differential control circuit

Abstract

The utility model provides a soft starting device multi-split motor magnetic balance differential control circuit, which comprises a soft starting device and at least one motor control loop, the soft starting device is connected with the motor control loop, each motor control loop comprises an outgoing line cabinet, an operation cabinet and a motor, the soft starting device is connected with the motor through the outgoing line cabinet, and the operation cabinet is connected with the motor. The motor is connected with a power grid through the operation cabinet, the operation cabinet is provided with a protection device and a first tripping loop, the outgoing line cabinet is provided with a second tripping loop, and a magnetic balance differential tripping outlet of the protection device is connected with the first tripping loop and the second tripping loop. The system can guarantee the safety and stability of the motor during starting and operation in a multi-split system.

Description

Technical Field

[0001] The utility model belongs to the technical field of motors, and particularly relates to a magnetic balance differential control circuit of a soft starting device with one motor driving multiple motors. Background Art

[0002] When the motor is started directly, the starting current is 4 to 7 times the rated current. If the power of the motor is relatively small, the impact on the power grid is not great, and it is generally allowed to start directly. However, for large motors, the instantaneous current at startup can reach hundreds of amperes or even thousands of amperes. Such a large current has a great impact on the power grid and will affect the normal operation of other loads on the same power grid. Therefore, in order to reduce the starting current, the motor is often started by soft starting, such as solid-state soft starting, autotransformer soft starting, variable frequency soft starting, etc.

[0003] In order to save costs, many large-capacity motor soft starters adopt a one-to-many mode of starting. Take the 1# motor as an example: when the motor is operating normally, for the magnetic balance transformers 11TAa, 11TAb, and 11TAc, the current flowing into the beginning of each phase is the same as the current flowing into the neutral point end. The current is one in and one out, the primary ampere-turn of the transformer is zero, no current is generated on the secondary side, and the protection does not work. When a phase-to-phase short circuit occurs in the motor winding or lead wire, the fault current destroys the flux balance of the 11TAa, 11TAb, and 11TAc current transformers, and current is generated on the secondary side. When the current exceeds the set value, the protection device operates to cut off the circuit breaker of the motor running cabinet. However, when starting with a one-to-many mode, it is often easy to ignore that within tens of seconds of starting, the magnetic balance differential protection cannot effectively protect the motor when a phase-to-phase short circuit occurs in the motor winding or lead wire. Utility Model Content

[0004] In view of this, the purpose of the utility model is to provide a magnetic balance differential control circuit for a soft starter with multiple motors, which solves the problem that the prior art cannot effectively protect the motors during startup and operation.

[0005] The purpose of the utility model can be achieved through the following technical solutions: a soft start device with a magnetic balance differential control circuit for multiple motors, comprising a soft start device and at least one motor control circuit, wherein the soft start device is connected to the motor control circuit, and is characterized in that each of the motor control circuits comprises an outlet cabinet, an operation cabinet and a motor, the soft start device is connected to the motor through the outlet cabinet, the motor is connected to the power grid through the operation cabinet, the operation cabinet has a protection device and a first tripping circuit, the outlet cabinet has a second tripping circuit, and the magnetic balance differential tripping outlet of the protection device is respectively connected to the first tripping circuit and the second tripping circuit.

[0006] The principle of the utility model is: by connecting the magnetic balance differential tripping outlet (two ways) of the protection device of the motor running cabinet, one way is connected to the tripping circuit of the running cabinet, and the other way is connected to the tripping circuit of the outlet cabinet, so that whether in the starting or running process, if the phase-to-phase short circuit of the motor winding or the lead-out line occurs, the protection device can be effectively operated to achieve the purpose of protecting the motor.

[0007] Preferably, the soft start device is connected to the power grid via a soft start power supply cabinet.

[0008] Preferably, the operating cabinet also includes a first selection module, a first local closing module, a first local opening module, a remote closing module, a closing coil and an opening coil, the first selection module is respectively connected to the first local closing module and the remote closing module, the first local closing module and the remote closing module are commonly connected to the closing signal input end of the protection device, and the signal output end of the protection device is respectively connected to the closing coil and the opening coil.

[0009] Preferably, the operating cabinet further includes a jump position monitoring module, and the jump position monitoring module is connected to the protection device.

[0010] Preferably, the operation cabinet further comprises a closing position monitoring module, and the closing position monitoring module is connected to the protection device.

[0011] Preferably, the outgoing line cabinet also includes a second selection module, a second local closing module, a second local opening module, a soft-start cabinet closing module, and a soft-start cabinet opening module, and the second selection module is respectively connected to the second local closing module and the soft-start cabinet closing module.

[0012] Compared with the prior art, the magnetic balance differential control circuit of the soft starter with one motor driving multiple motors has the following advantages: by connecting the magnetic balance differential tripping outlet of the protection device to the tripping circuits of the operating cabinet and the outgoing cabinet respectively, the problem that the magnetic balance differential cannot effectively protect the motor operation and starting safety when the one motor driving multiple motors is started is effectively solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The invention is a circuit principle diagram of a magnetic balance differential control circuit of a soft starting device driving multiple motors in an embodiment.

[0014] Figure 2 It is a schematic diagram of the operation cabinet of the embodiment.

[0015] Figure 3 It is a schematic diagram of the outlet cabinet of the embodiment. DETAILED DESCRIPTION

[0016] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0017] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present utility model, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0018] In the present invention, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0019] The utility model provides a magnetic balance differential control circuit of a soft starting device with multiple motors, which is used for protecting the starting of the multiple motors, thereby ensuring the safe starting and operation of the motors and reducing the impact on other loads of the power grid.

[0020] Specifically, Figure 1 As shown, in this embodiment, a one-to-two soft starter is taken as an example: it includes a soft starter and two motor control circuits, the soft starter is connected to the motor control circuit, each motor control circuit includes an outlet cabinet, an operating cabinet and a motor, the soft starter is connected to the motor through the outlet cabinet, the motor is connected to the power grid through the operating cabinet, the operating cabinet has a protection device 1n and a first tripping circuit, the outlet cabinet has a second tripping circuit, the magnetic balance differential tripping outlet of the protection device 1n is respectively connected to the first tripping circuit and the second tripping circuit, the soft starter is connected to the power grid through the soft starter power cabinet, and the other end is respectively connected to the outlet cabinets corresponding to the two motor control circuits. It should be noted that in the two motor control circuits in this embodiment, they correspond to the 1# motor and the 2# motor respectively, and each motor is matched with the corresponding numbered operating cabinet and outlet cabinet.

[0021] Taking the motor control circuit corresponding to motor 1# as an example, its control circuit is as follows:

[0022] like Figure 2As shown, the operation cabinet includes: a first selection module composed of a conversion switch SA1; a first local closing module and a first local opening module composed of a conversion switch SA2; a remote closing module, a closing coil and an opening coil. The conversion switch SA1 is connected to the 3rd pin of the conversion switch SA2 and the remote closing module respectively, and the 4th pin of the conversion switch SA1 and the remote closing module are connected to the 111th pin of the protection device to provide a closing signal. The signal output end of the protection device is connected to the closing coil and the opening coil respectively. The protection device of the operation cabinet and the neutral point of the 1# motor are connected through magnetically balanced current transformers 11TAa, 11TAb, and 11TAc to form a first tripping circuit, thereby obtaining an induced current signal to trigger a tripping action. Pins 1 and 2 of the conversion switch SA2 serve as the opening signal triggering device of the first local opening module to provide a local opening signal to the protection device 1n.

[0023] In addition, the operating cabinet of this embodiment further includes a tripping monitoring module and a closing monitoring module, and both the tripping monitoring module and the closing monitoring module are connected to the protection device.

[0024] like Figure 3 As shown, the outgoing line cabinet includes a second selection module composed of a transfer switch SA1; a second local closing module and a second local opening module composed of a transfer switch SA2; a soft start cabinet closing module and a soft start cabinet opening module. The second selection module is connected to the second local closing module and the soft start cabinet closing module respectively. The magnetic balance differential tripping outlet of the protection device 1n of the running cabinet is connected in parallel to the second local opening module, and then connected to the second local opening coil.

[0025] The following figure further illustrates the working principle of the utility model using the soft starting process of motor 1#:

[0026] The order of starting the 1# motor is as follows: after the soft starter receives the start command of the 1# motor, the 1# outlet cabinet circuit breaker 4QF is closed, and the 1# motor is started through the soft starter (1QF is not closed at this time). If the motor winding or lead wire is short-circuited during the start-up process of the 1# motor, the secondary side of the magnetic balance transformer 11TAa, 11TAb, 11TAc generates current. When the current exceeds the set value, the protection device will be activated to cut off the 1# motor running cabinet circuit breaker 1QF (this circuit breaker was originally in the open state, so it remains in its original state) and the 1# outlet cabinet circuit breaker 4QF. If the 1# motor is started and enters the running state, and the stator winding is short-circuited at this time, the 1# motor running cabinet 1QF and the 1# outlet cabinet 4QF will trip respectively after receiving the trip command (at this time, the start-up has been completed, and the 1# outlet cabinet was originally in the open state, so the 1# outlet cabinet remains in its original state). Therefore, using this method, the magnetic balance differential protection can protect the motor during both the start-up and operation processes. When starting other motors, the principle is the same as that of motor #1.

[0027] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A magnetic balance differential control circuit of a soft starter with multiple motors, comprising a soft starter and at least one motor control circuit, wherein the soft starter is connected to the motor control circuit, and characterized in that: Each of the motor control circuits includes an outlet cabinet, an operating cabinet and a motor. The soft starter is connected to the motor via the outlet cabinet, and the motor is connected to the power grid via the operating cabinet. The operating cabinet has a protection device and a first tripping circuit, and the outlet cabinet has a second tripping circuit. The magnetic balance differential tripping outlet of the protection device is respectively connected to the first tripping circuit and the second tripping circuit.

2. A magnetic balance differential control circuit for multiple motors in a soft starter device according to claim 1, characterized in that: The soft start device is connected to the power grid through a soft start power supply cabinet.

3. A magnetic balance differential control circuit for multiple motors in a soft starter device according to claim 1 or 2, characterized in that: The operating cabinet also includes a first selection module, a first local closing module, a first local opening module, a remote closing module, a closing coil and an opening coil. The first selection module is respectively connected to the first local closing module and the remote closing module. The first local closing module and the remote closing module are commonly connected to the closing signal input end of the protection device. The signal output end of the protection device is respectively connected to the closing coil and the opening coil.

4. A magnetic balance differential control circuit for multiple motors in a soft starter device according to claim 3, characterized in that: The operating cabinet also includes a jump position monitoring module, and the jump position monitoring module is connected to the protection device.

5. The magnetic balance differential control circuit of a soft starter with multiple motors according to claim 3, characterized in that: The operation cabinet further comprises a closing position monitoring module, and the closing position monitoring module is connected to the protection device.

6. A magnetic balance differential control circuit for multiple motors in a soft starter device according to claim 1 or 2, characterized in that: The outgoing line cabinet also includes a second selection module, a second local closing module, a second local opening module, a soft-start cabinet closing module, and a soft-start cabinet opening module. The second selection module is respectively connected to the second local closing module and the soft-start cabinet closing module.

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