JPH09163775A - Motor starting/stopping device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor starting/stopping device which can prevent the malfunction of a circuit breaker or a breaker due to the restrating current of a motor when restarting is performed in a short time. SOLUTION: A time-limit relay 2 performs a time-limit operation after a certain time when any one of a plurality of starting instructions is established, and it is returned instantaneously when the starting instruction is released. Then, an electromagnetic contactor 4 establishes a power supply circuit 3 to supply a power supply to a motor 1 when the time-limit relay 2 is operated, and it does not establish the power supply circuit 3 when the time-limit relay 2 is returned. When a restarting instruction is delayed, it is possible to prevent the stop of the motor caused by an overcurrent when the motor is restarted immediately after the motor is stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor starting / stopping device configured so that one electric motor can be started by a plurality of independent start commands.

[0002]

2. Description of the Related Art For example, in a power supply facility for a power plant, there is a motor start / stop device having a start / stop function for a motor that enables start / stop operation under a plurality of start conditions and stop conditions.

In general, most of the electric motors used as auxiliary equipment of a power plant are inexpensive and easily maintained induction motors. Further, since the induction motor used generally has a large power source capacity, a full voltage starting method is usually adopted to simplify the starting circuit. On the other hand, in a power generation plant, in order to improve operability, many start-up / stop devices for electric motors, which are auxiliary devices of the plant, have a plurality of start-up commands and stop signals.

[0004] Such an induction motor as a plant auxiliary machine has a characteristic that a residual voltage is generated at the time of its stop, and the voltage decreases while the phase difference increases from the power supply voltage with time immediately after the stop. Are known. It is also known that when the phase difference and the voltage difference between the residual voltage and the power supply voltage are large, if the electric motor is restarted, a current larger than the normal starting current is generated.

[0005]

However, in the prior art, when the motor start command is issued, the motor is immediately restarted. Therefore, the power supply voltage phase and the residual voltage level of the motor at the time of restart are restarted. When the phase difference is 180 degrees, a large restart current flows. As a result, the protective relay and the circuit breaker for wiring may malfunction and may not be restarted.

As described above, when a plurality of these start commands and stop signals are repeatedly generated within a short period of time and the power supply voltage phase at the time of restart and the residual voltage phase difference of the motor are 180 degrees, a large restart occurs. Starting current may flow, which may cause malfunction of the protective relay and wiring breaker. In addition, when such an event occurs with respect to an auxiliary machine that is important for plant operation, it is possible that not only the auxiliary machine cannot be operated, but also the plant operation is affected.

Therefore, when a plurality of electric motor start commands are repeatedly generated within a short time, the electric motor is frequently started and stopped, and an excessive restart current flows, which affects the insulation of the electric motor and the power supply equipment. Since the operation of a circuit breaker for wiring is considered, improvement has been required.

That is, the conventional motor start / stop device does not consider the restart current. Therefore, depending on the characteristics of the circuit breaker for the motor protection circuit in the start circuit or the characteristics of the protective relay, the The circuit breaker or the circuit breaker operated and sometimes became unable to start.

An object of the present invention is to provide an electric motor start / stop device capable of preventing malfunction of a circuit breaker or a circuit breaker due to a motor restart current when a restart occurs within a short time. .

[0010]

According to a first aspect of the present invention, there is provided an electric motor start / stop device configured to start one electric motor by a plurality of independent start commands. When either of them is established, the electric power is supplied to the electric motor after a fixed time period.

According to the first aspect of the present invention, by delaying the restart command, the motor stop due to the overcurrent at the time of restart immediately after the stop of the motor is avoided.

According to a second aspect of the present invention, there is provided a motor start / stop device configured to start one electric motor by a plurality of independent start commands, and one of the plurality of start commands is satisfied. A time relay that operates for a fixed time after a certain period of time and returns instantly when the start command is released,
An electromagnetic contactor that establishes a power supply circuit for supplying power to the electric motor when the time delay relay operates and disables the power supply circuit when the time delay relay returns.

According to the second aspect of the invention, the time delay relay operates for a fixed time after a certain time limit when any of the plurality of start commands is satisfied, and instantaneously returns when the start command is released. The electromagnetic contactor establishes a power supply circuit for supplying power to the electric motor when the time delay relay operates, and deactivates the power supply circuit when the time delay relay returns.

According to a third aspect of the present invention, there is provided a motor starting / stopping device configured to start one electric motor by a plurality of independent start commands, and one of the plurality of start commands is satisfied. A time relay that operates for a fixed time after a certain period of time and returns instantly when the start command is released,
A closing coil that establishes a power supply circuit to supply power to the electric motor when the time delay relay operates and maintains that state, and a trip that maintains the state by disabling the power supply circuit when there is a motor stop command. And a coil.

According to the third aspect of the invention, the time delay relay operates for a fixed time after a certain time limit when any of the plurality of start commands is satisfied, and instantaneously returns when the start command is released. Then, the closing coil establishes a power supply circuit for supplying power to the electric motor when the time delay relay operates and holds the state, and the trip coil disables the power supply circuit when there is a command to stop the electric motor. Hold the state.

According to a fourth aspect of the present invention, there is provided an electric motor start / stop device configured so that one electric motor can be started by a plurality of independent start commands. During this period, the output of the start command is blocked, and after the time period has elapsed, the start command is permitted and power is supplied to the electric motor.

According to the fourth aspect of the invention, the restart command is delayed for a certain period of time after the stop command is issued. This avoids stopping the motor due to overcurrent at the time of restart immediately after the motor is stopped.

According to a fifth aspect of the present invention, there is provided an electric motor start / stop device configured to start one electric motor by a plurality of independent start commands. Establishes a time delay relay that returns when the stop command is released, and a power supply circuit that supplies power to the motor when the time delay relay is returning and one of the multiple start commands is satisfied. A closing coil that holds the state and a trip coil that holds the state when the electric motor stop command is issued and the power supply circuit is not established are provided.

According to the invention of claim 5, the time delay relay operates instantaneously when a stop command is issued to the electric motor, and returns to the time limit when the stop command is released. Then, the closing coil establishes a power supply circuit for supplying power to the electric motor when the time relay is restored and any of the plurality of start commands is satisfied, and maintains the state, and the trip coil is When the motor stop command is issued, the power supply circuit is not established and the state is maintained.

The invention of claim 6 is the first to fifth aspects of the present invention.
In the above invention, the fixed time period is a time period required for extinguishing the residual voltage generated when the electric motor is stopped.

In the sixth aspect of the present invention, in addition to the effects of the first to fifth aspects of the present invention, the start command is output after a time period required to eliminate the residual voltage generated when the electric motor is stopped.

[0022]

Embodiments of the present invention will be described below. FIG. 1 is a circuit diagram showing a first embodiment of the present invention. In the first embodiment, a plurality of start commands A,
When any one of B and C is satisfied, the electric power is supplied to the electric motor 1 after a certain period of time, and when any of the plurality of start commands A, B and C is satisfied. , A time-delay relay 2 that operates in a time-delayed state after a certain period of time and returns instantly when a start command is released, and this time-delay relay 2
Is provided, the power supply circuit 3 for supplying power to the electric motor 1 is established, and the electromagnetic contactor 4 is established when the time delay relay 2 is restored.

In FIG. 1, A, B, and C indicate contacts of respective automatic start commands. These three contacts turn on when there is a start command, and operate independently of each other.
The start commands are duplicated or congestion occurs within a short time.

Now, assume that the condition of the start command A is satisfied and the electric motor 1 is operating. In this state, the power supply circuit 3
The internal circuit breaker 5 is closed, and the electromagnetic contactor 4
The seed contact E of is also closed. After that, when the start command A is not satisfied and the voltage to the time delay relay 2 disappears, the coil of the time delay relay 2 becomes non-excited, so that the operating contact D of the time delay relay 2 opens instantly. As a result, the coil of the electromagnetic contactor 4 is de-excited, the main contact E in the power supply circuit 3 is opened, and the electric motor 1 is stopped.

With the start command A not satisfied,
When the start command B or the start command C is satisfied, the contact D of the time delay relay 2 is not closed until the time delay relay 2 starts the time delay operation and a preset time period elapses. Therefore, the restart of the electric motor 1 will be operated with a delay only for the time period set in the time delay relay 2.

As described above, even if a restart command is issued within a short period of time, the electric motor 1 is delayed in the instantaneous restart due to the time delay operation of the time delay relay 2. Since the residual voltage of the electric motor 1 is reduced within this delay time, even if the electric motor 1 starts restarting after the set time limit, the disconnection malfunction due to the operation characteristics of the wiring breaker 5 does not occur. Therefore, malfunction of the circuit breaker 5 for wiring can be prevented.

Next, FIG. 2 shows a second embodiment of the present invention. The second embodiment is an electric motor starting / stopping device using an air circuit breaker, a vacuum circuit breaker and a circuit breaker 6 instead of the wiring circuit breaker 5 of the first embodiment shown in FIG. Yes,
When any one of the plurality of start commands is satisfied, the time relay operates for a fixed time after a certain time limit, and returns instantly when the start command is released, and the motor 1 is powered when the time relay 2 operates. A closing coil 7 that establishes a power supply circuit 3 for supplying and holds the state, and an electric motor 1
And a trip coil 8 for disabling the power supply circuit 3 when there is a stop command.

In FIG. 2, the electric motor 1 is started and stopped by exciting the closing coil 7 and the trip coil 8 for opening and closing the circuit breaker 6, respectively. That is, the starting of the electric motor 1 is performed by the closing coil 7, and the stopping of the electric motor 1 is performed by the trip coil 8. Further, A, B, and C represent contacts of respective start commands, and F represents contacts of stop commands. These three contact points A, B, and C operate independently of each other, and start commands are duplicated or congestion occurs within a short time.

Now, it is assumed that the condition of the start command A is satisfied and the electric motor 1 is operating. After that, when the stop command F is satisfied and the trip coil 8 is excited, the circuit breaker 6 is opened to stop the electric motor 1. If the start command B or the start command C operates in this state, the contact D of the time delay relay 2 is not closed until the time delay relay 2 starts the time delay operation and a preset time period elapses. Therefore, the closing coil 7 is not excited until the time limit of the time delay relay 2 elapses, and the motor 1
Delay the restart of.

As described above, the instantaneous restart of the electric motor 1 is delayed. Since the residual voltage of the electric motor 1 decreases within this delay time period, even if the electric motor 1 starts restarting after the set time period, it is connected to the current transformer 9 for an instrument installed in the power supply circuit 3 of the electric motor 1. It is possible to prevent the disconnection malfunction due to the protective relay 10 that occurs.

Next, FIG. 3 shows a third embodiment of the present invention. Like the second embodiment shown in FIG. 2, the third embodiment is an electric motor starting / stopping device using an air circuit breaker, a vacuum circuit breaker, and a circuit breaker 6, and The output of the start command is blocked for a certain time period after the stop command F is issued, and after the time limit has elapsed, the start command is permitted and power is supplied to the electric motor.

That is, when there is a stop command for the electric motor 1, it operates instantaneously, and when the stop command is canceled, the time delay relay 2 and the time delay relay 2 return, and there are a plurality of start commands. When any one of them is satisfied, the closing coil 7 that establishes the power supply circuit 3 for supplying power to the electric motor 1 and holds the state and the power supply circuit 3 when the stop command F of the electric motor 1 is given. It is provided with a trip coil 8 that is not established and holds the state.

In FIG. 3, the start and stop of the electric motor 1 is carried out by exciting the closing coil 7 and the trip coil 8 for opening and closing the circuit breaker 6, respectively. That is, the starting of the electric motor 1 is performed by the closing coil 7, and the stopping of the electric motor 1 is performed by the trip coil 8. Further, A, B, and C represent contacts of respective start commands, and F represents contacts of stop commands. These three contact points A, B, and C operate independently of each other, and start commands are duplicated or congestion occurs within a short time.

Now, assume that the condition of the start command A is satisfied and the electric motor 1 is operating. In this state, the stop command F is open, and the time delay relay 2 is in a state of being restored.
Therefore, the time contact G is closed. In this state, when the stop command F is satisfied and the trip coil 8 is excited, the circuit breaker 6 opens to stop the electric motor 1.

The time delay relay 2 installed in parallel with the trip coil 8 starts operating. The time delay contact G of the time delay relay 2 is a so-called b contact, which is a contact that is closed when the time delay relay 2 is restored and that is opened when the time delay relay 2 operates. Then, when the time delay relay 2 is restored (when the time delay contact G is closed), the time delay operation is performed. Therefore, when the stop command F is issued, the time-delay contact G is instantly opened, and when the stop command F is restored, the time-limit contact is restored at a predetermined time.

That is, the time delay contact G is kept open for a preset time period after the stop command F is returned and the stop command F returns. Therefore, the closing coil 7 is not excited even if any of the start commands is satisfied during this period, and the restart of the electric motor 1 is delayed. Since the residual voltage of the electric motor 1 decreases within this delay time, even if the restart of the electric motor 1 is started after the set time, the residual current of the electric motor 1 is connected to the instrument current transformer 9 installed in the power supply circuit 3 of the electric motor 1. The protective relay 6 does not malfunction.

As described above, according to the present invention, the time delay relay 2 is installed downstream of the start command contact or 2 downstream of the stop command contact, and the power supply of the electric motor 1 is supplied by the operation contacts D and G of the time delay relay 2. Contact E of electromagnetic contactor in circuit 3
Alternatively, the circuit breaker 6 is operated. As a result, even if the automatic start condition A is not satisfied and the start command contact A is opened, the motor 1 is stopped and the start command B or the start command C is satisfied immediately after that, the time delay operation of the time delay relay 2 causes , You can delay the restart for a certain period of time. Within this time, the electric motor 1 slows down and the residual voltage decreases. afterwards,
After the time limit set value of the time delay relay 2 has passed, the time delay operation contacts D and F are closed and the restart of the electric motor 1 is started. Even if the phase difference is large, an excessive restart current will not occur.

[0038]

As described above, according to the present invention, in an electric motor start / stop device having a plurality of start commands, delaying the restart of the electric motor by the time delay time of the time delay relay causes the electric motor to stop when the electric motor is stopped. The electric motor 1 can be restarted so as not to be affected by the residual voltage. That is, since the restart time is delayed until the residual voltage becomes sufficiently small, it is possible to prevent the generation of an excessive restart current caused by the residual voltage and the power supply voltage. As a result, it is possible to prevent the disconnection operation of the wiring breaker due to the restart current and the operating characteristics of the wiring breaker from occurring, and the restart failure does not occur.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a second embodiment of the present invention.

FIG. 3 is a circuit diagram showing a third embodiment of the present invention.

[Explanation of symbols]

 1 Motor 2 Time-relay 3 Power supply circuit 4 Electromagnetic contactor 5 Time-relay 6 Circuit breaker 7 Make-up coil 8 Trip coil 9 Current transformer 10 Protective relay 11 Relay

Claims (6)

[Claims] 1. An electric motor start / stop device configured to start one electric motor by a plurality of independent start commands, wherein any one of the plurality of start commands is satisfied after a fixed time period. An electric motor starting / stopping device adapted to supply power to the electric motor. 2. A motor starting / stopping device configured to be capable of starting one electric motor by a plurality of independent start commands, and when any one of the plurality of start commands is satisfied, a fixed time period elapses. When the time delay operation and the start command are canceled, the time delay relay is instantly restored, and when the time delay relay operates, a power supply circuit for supplying power to the electric motor is established to restore the time delay relay. An electric motor starting / stopping device, comprising: an electromagnetic contactor that does not establish a power supply circuit. 3. A motor starting / stopping device configured to start one electric motor by a plurality of independent start commands, wherein any one of the plurality of start commands is satisfied after a fixed time period. A time delay relay that operates for a time and returns instantly when the start command is released; and a closing coil that establishes a power supply circuit for supplying power to the electric motor when the time relay operates and holds the state. An electric motor start / stop device, comprising: a trip coil that holds the power supply circuit in a non-established state when a stop command is issued to the electric motor. 4. An electric motor start / stop device configured to start one electric motor by a plurality of independent start commands, wherein the start command is issued for a certain period of time after the electric motor stop command is issued. An electric motor starting / stopping device that blocks output and permits the start command after a lapse of the time limit to supply power to the electric motor. 5. A motor start / stop device configured to start one motor by a plurality of independent start commands, when a stop command for the motor is issued, the motor is instantaneously operated and the stop command is released. And a power supply circuit for supplying power to the electric motor when the time relay has been recovered and one of the plurality of start commands is satisfied. An electric motor starting / stopping device, comprising: a closing coil for holding a state, and a trip coil for holding the power supply circuit in a non-established state and a state thereof when a stop command for the electric motor is given. 6. The electric motor start / stop device according to claim 1, wherein the fixed time period is a time period required for eliminating a residual voltage generated when the electric motor is stopped.