JPS6321153Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a control circuit for an electric cargo handling machine, such as an electric hoist or an overhead crane, which has a drive motor installed at a high place and hoists and traverses a load.

[Prior art] Among electric cargo handling machines, overhead cranes and hoists with electric trolleys that hoist, travel, and traverse loads by driving an electric motor are well known. The hoist is made up of a club or trolley that moves across the bridge girder and is equipped with an electric motor for traveling, traversing, and hoisting. The hoisting capacity is 125~30000KgW.
Both hoisting and running are performed using ropes or chains lowered to near the floor, and a three-phase squirrel cage induction motor equipped with an electromagnetic brake is used as the driving motor.

Next, the conventional electric hoist mentioned above will be explained in detail with reference to FIGS. 2 to 5.

In FIG. 2, a hoist 12 is suspended from a rail 10 installed at a high place in a factory or warehouse so that it can move along the rail 10. A hoisting motor that drives the cylinder and a traversing motor that causes the hoist 12 to traverse in the direction along the rail 10 are installed inside.

Further, a controller 14 including an electromagnetic contactor (not shown) and the like for controlling the drive of the hoisting motor and the traversing motor is provided outside the hoist 12. An operation push button switch 16 for opening and closing the hoisting motor or the traversing motor to drive or stop the hoisting motor or the traversing motor is suspended from the hoist 12 by a cable 18 to near the floor surface.

When a hoisting switch (not shown) in the operation push button switch 16 is pressed, the hoisting motor is started and the hook 22 suspended from the winding drum by a rope 20 is raised. Also, rail 1
When the hoist 12 is to be moved laterally along 0, the traversal motor within the hoist 12 is driven by pressing the traverse switch of the operation push button switch 16.

A control circuit for driving and controlling the hoisting motor and the traversing motor described above will be explained in detail with reference to FIG.

In the figure, a hoisting motor 24 and a traversing motor 26 are connected to each phase R, respectively, of a delta connection of a three-phase AC power supply 28.
S and T, and the hoisting motor 24 and the traversing motor 26 are driven by power supplied from the three-phase AC power supply 28.

On the other hand, wires 30 and 32 are pulled out from the middle of each wire of the ungrounded phase R and grounded phase S of the power supply 28, and the other end of the wire 30 is connected to the operation push button switch 1.
6 switches 16a to 16d.

Note that the switch 16a is for winding, and the switch 1 is for winding.
6b is for lowering, switch 16c is for eastward traverse, and switch 16d is for westward traverse.

Further, one end of the wiring 32 connected to the ground phase S side of the power source 28 is connected to one end of each excitation coil 34a to 40a of an electromagnetic contactor 34 to 40 provided corresponding to each of the switches 16a and 16d. , the other end of each excitation coil 34a to 40a is connected to the first
Plate contact 42 of step overwinding limit switch 42
It is connected to the other contact point of each switch 16a to 16d of the operation push button switch 16 via terminals a to 42d.

And the make contact 34b of the electromagnetic contactor 34,
34c, 34d and the make contacts 36b, 36c, 36d of the electromagnetic contactor 36 are provided between the power supply 28 and the hoisting motor 24, and, for example, when the hoisting switch 1
6a to turn on the excitation coil 34a of the electromagnetic contactor 34.
When energized, the make contacts 34b to 34d close, power is supplied from the power source 28 to the hoisting motor 24, and the motor 24 becomes a hoisting drive.

Also, when the switch 16b for lowering the load is pressed, the make contacts 36b, 36c of the electromagnetic contactor 36,
36d closes and the hoisting motor 24 rotates in the opposite direction, lowering the load hung on the hook.

Similarly, if the switch 16c is pressed, the electromagnetic contactor 3
The make contacts 38b, 38c, 38d of the magnetic contactor 40 are closed and the load is moved eastward by the drive of the traversing motor 26, and when the switch 16d is pressed, the make contacts 40b, 40c, 40d of the electromagnetic contactor 40 are closed and the traversing motor 26 is driven to move the load eastward. The counter-rotating drive moves the cargo westward.

In addition, an electromagnetic brake 44 using an AC electromagnet is built in on the opposite side of the hoisting motor 24, and the power source 2
8 is applied to the hoisting motor 24 as a motor drive, and at the same time the brake winding 44 of the electromagnetic brake 44
Voltage is also applied to a, and the attraction force of the electromagnet pushes back a braking spring (not shown) to loosen the brake and rotate the hoisting motor 24.
When the power supply from the hoisting motor 24 is cut off, the brake disk is pressed against the brake lining by the braking spring, and a braking torque is applied to bring the hoisting motor 24 to a sudden stop.

The control circuit consisting of the electromagnetic contactors 34 to 40, etc. is housed in a controller 14 shown in FIG. Excitation coils 34a~ of electromagnetic contactors 34~40
40a, for example, one end of the exciting coil 34a is connected to the ground phase S of the power source 28 as shown in FIG. 4, even if the exciting coil 34a causes a grounding accident, the exciting coil 34a However, if one end of the excitation coil 34a is not connected to the ground phase S of the power supply 28, if current leaks due to a ground fault, etc., the current will not flow and run away, but as shown in FIG. Phase S and excitation coil 34
A closed circuit as shown by the broken line is generated between the wiring phases connected to one end of a, and the excitation coil 34a is excited, and its make contacts 34b to 34d are closed, and the hoisting motor 24 is operated by the operating push button switch 16a. Hoist 12 was driven without pressing
There was a risk of an accident resulting in the vehicle running out of control.

The above-mentioned runaway of the hoist 12 is due to the fact that the excitation coil 34a is not connected to the ground phase S, and such incorrect connection may occur even during the initial installation of the hoist, and in particular, it may cause the hoist to malfunction. Often occurs during exchanges.
In particular, in the latter hoist replacement, the entire hoist is usually replaced, and when wiring the power supply circuit at the time of such replacement, there may often be a misconnection in which the ground phase S is not connected to the excitation coil. There was no check mechanism for such cases.

Even if an incorrect connection of the ground phase occurs during the above-mentioned replacement, the conventional check merely checks whether the hoist can be moved up and down or driven in the east-west direction. However, under normal circumstances, the hoist itself operates normally, and in particular during testing, the hoist is operated slowly under a light load without sudden movements, as mentioned above. A ground fault such as a ground fault does not occur, and runaway does not occur.

Therefore, during such new installation or especially during replacement, the erroneous connection may be overlooked.

Therefore, in order to prevent this runaway accident, a work is carried out to check the quality of the ground phase S. Conventional control circuits include a power indicator lamp and a special ground phase inspection to check the quality of the ground phase. Conventional grounding phase inspections involve the risk of electric shock and the need to work at heights, as workers are inspecting the controller 14 by applying a voltage detector to the control circuit connections at a high location. There is a risk of falling accidents, and there is also the disadvantage that the number of man-hours required to inspect the ground phase is large and the inspection time is long.

[Purpose of the invention] The present invention was devised in view of the above-mentioned drawbacks of the conventional devices. An object of the present invention is to provide a control circuit for an electric cargo handling machine that can check the quality of the cargo handling machine.

[Structure of the invention] In order to achieve this object, the present invention provides a control circuit for an electric cargo handling machine that is provided with an electromagnetic contactor and that operates the electromagnetic contactor to control the operation of an electric motor driven by three-phase alternating current. , the control circuit includes an energization indicator lamp and a changeover switch inserted in series between the ground side end of the excitation coil in the electromagnetic contactor and the non-grounded phase of the three-phase AC power supply, and the control circuit includes the changeover switch. The present invention is characterized in that it includes a ground phase inspection circuit that connects one fixed contact side of the switch to ground and causes the energization indicator lamp to also serve as a ground phase inspection lamp.

[Embodiment of the invention] A preferred embodiment of the invention will be described below with reference to FIG.

In addition, in the figures, the same reference numerals as in FIGS. 2 to 5 above indicate the same components.
Explanation of these items with the same number will be omitted.

The characteristic feature of the present invention is that each excitation coil 34a to 34a of the electromagnetic contactors 34 to 40 is added to the conventional control circuit.
A changeover switch 46 and an energization indicator lamp 48 are inserted in series between one end of the side connected to the ground phase of the power supply 28 of the power supply 28 and the non-grounded phase of the power supply 28, and one fixed contact side of the changeover switch 46 is inserted in series. The present invention is equipped with a ground phase inspection circuit that connects to the ground and uses the energization indicator lamp as a ground phase inspection lamp.According to the control circuit of the electric hoist of this embodiment shown in FIG. When the movable contact piece is brought into contact with the fixed contact B side, the energization indicator lamp 48 of the ground phase inspection circuit lights up and can be used as an energization light.

That is, according to the present invention, by lighting the energization indicator lamp 48, it is possible to confirm that the circuit connection of the controller 14 is reliably connected to the power source 28.

When inspecting the ground phase, the movable contact of the changeover switch 46 is switched so as to contact the fixed contact A side, and at this time, one end of each excitation coil 34a to 40a is not connected to the ground phase of the power source 28, and the excitation coil When both ends of 34a to 40a are connected to the non-grounded phase of the power supply 28, current flows through the grounded phase inspection circuit and the energization indicator lamp 48 lights up.
The difference in grounding between a to 40a can be easily recognized.

In addition, if one end of the excitation coils 34a to 40a is correctly connected to the ground phase S of the power supply 28 with the movable contact piece of the switch 46 tilted toward the fixed contact A side, the energization indicator lamp 48 goes out and the ground phase is found to be good.

Therefore, according to the present invention, at the time of initial installation and when replacing the hoist, simply by operating the switch 46, the excitation coil of the controller 14 can reliably connect one end of the excitation coil to the ground phase S of the power source 28. You can confirm that it is. and,
By this confirmation, even if a ground fault occurs subsequently, it is possible to reliably prevent the hoist from running out of control.

As described above, the present invention makes it possible to confirm the correct connection of the controller to each phase of the power supply simply by operating a switch, and this confirmation can be done by workers at high places, unlike in the past. Electric shocks, falling accidents, etc. can be prevented without the need for on-site inspections.

Further, according to the present invention, there is an advantage that the indicator lamp can be used to separately check both the energization indication of the controller and the fact that the ground phase is reliably connected.

[Effects of the invention] As explained above, according to the invention, it is possible to know whether the ground phase, which causes runaway, is good or bad by simply switching the changeover switch.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the control circuit of the electric cargo handling machine of the present invention, Fig. 2 is an explanatory diagram of an electric hoist, and Fig. 3 is a control circuit of a conventional electric hoist.
FIG. 4 is a circuit diagram in which one end of the excitation coil is connected to the ground side, and FIG. 5 is a circuit diagram in which both ends of the excitation coil are connected to the non-contact side. 24... Hoisting motor, 28... Three-phase AC power supply, 34
~40...Magnetic contactor, 34a~40a...Exciting coil, 46...Selector switch, 48...Electrification indicator lamp.

Claims (1)

[Scope of utility model registration request] In a control circuit of an electric cargo handling machine that is provided with an electromagnetic contactor and operates the electromagnetic contactor to control the operation of an electric motor driven by three-phase alternating current, the ground side end of the excitation coil in the electromagnetic contactor and the three-phase The control circuit includes an energization indicator lamp and a changeover switch inserted in series between a non-grounded phase of an AC power source, and the control circuit includes a fixed contact side of the changeover switch that is grounded to ground the energization indicator lamp. A control circuit for an electric cargo handling machine, characterized in that it is equipped with a grounded phase inspection circuit that also serves as a phase inspection lamp.