CN117923352A - Electric hoist detection method, auxiliary device and electric hoist applying same - Google Patents

Abstract

The invention relates to an electric hoist detection method, an auxiliary device and an electric hoist using the same. The detection method of the electric hoist comprises the following steps: configuring a normal operation mode and a bypass operation mode for the electric hoist; when the electric hoist is in a normal operation mode, limit function detection is carried out on the primary height limiter, and when the electric hoist is in a bypass operation mode, limit function detection is carried out on the secondary height limiter after the electric switch bypass of the primary height limiter is in short circuit. The electric hoist detection auxiliary device comprises a bypass circuit capable of being connected or disconnected and shorting the electric switch bypass of the primary height limiter when being connected, and a change-over switch for controlling the bypass circuit to be connected or disconnected. The electric hoist comprises a first-stage height limiter, a second-stage height limiter and the electric hoist detection auxiliary device. The invention has the advantages of easy realization, simple operation, lower cost and higher safety.

Description

Electric hoist detection method, auxiliary device and electric hoist applying same

Technical Field

The invention relates to the technical field of hoisting equipment and detection thereof, in particular to a method for detecting a height limiter in an electric hoist, an auxiliary device and the electric hoist using the auxiliary device.

Background

The electric hoist is common hoisting equipment, and according to the regulations of related safety regulations, the electric hoist is required to be provided with a heavy hammer type height limiter and a fire-cut type height limiter when leaving a factory, wherein the heavy hammer type height limiter is used as a primary height limiter, and a lifting control loop is cut off by disconnecting a lifting relay in a control system of a lifting mechanism, so that the height limiting is realized; the fire-cut-off type height limiter is used as a secondary height limiter, and the height limit is realized by cutting off a power supply of the lifting mechanism. The limiting height corresponding to the heavy hammer type height limiter is lower than the limiting height corresponding to the fire-cutoff type height limiter.

In the daily use spot inspection, maintenance and inspection and detection work of the electric hoist, a method and defects thereof which are commonly used are as follows:

1. The lifting mechanism of the electric hoist is controlled to move upwards through the lifting button on the controller of the electric hoist, and when the lifting mechanism reaches the limiting height corresponding to the heavy hammer type height limiter, the heavy hammer type height limiter breaks off the control loop of the lifting mechanism, so that the height limiter of the electric hoist is considered to have good functions. In this way, the point inspection, maintenance and servicing of the fire-cut height limiter is neglected, thereby creating a risk of failure of the secondary height limiter;

2. After the function of the heavy hammer type height limiter is detected, maintenance personnel or special equipment inspection and detection personnel perform high-altitude operation by using auxiliary equipment such as a boarding car and the like, and the electric switch of the heavy hammer type height limiter is pulled, so that the function of the fire-cut type height limiter is detected, and the power supply of the lifting mechanism can be cut off by confirming the function of the fire-cut type height limiter. This way has the risk of working aloft and the inspection cost is high;

3. After the function of the heavy hammer type height limiter is detected, a detector uses tools such as a long rod to assist in picking up the heavy hammer line of the heavy hammer type height limiter, so that an electric switch connected with the heavy hammer is still in a closed and electrified state, and then the function of the fire-cut type height limiter is further operated and checked. This approach is only suitable for electric hoists with low lifting heights, and there is a risk that the long rod will interfere with the relevant lifting mechanism to cause unnecessary damage and drop of the components.

Therefore, the detection scheme of the electric hoist needs to be improved so as to safely, comprehensively and inexpensively complete the function verification of the two-stage height limiter in the electric hoist.

Disclosure of Invention

The invention aims to provide the electric hoist detection method which is easy to realize, simple to operate, low in cost and high in safety.

In order to achieve the above purpose, the invention adopts the following technical scheme:

The utility model provides an electric block detection method for carry out the function detection to the electric block that has first-level high stopper and second-level high stopper, electric block detection method does: configuring a normal operation mode and a bypass operation mode for the electric hoist; when the electric hoist is in the normal operation mode, limit function detection is carried out on the primary height limiter, and when the electric hoist is in the bypass operation mode, limit function detection is carried out on the secondary height limiter after the electric switch bypass of the primary height limiter is in short circuit.

And the bypass short circuit of the electric switch of the primary height limiter is realized in a remote electric control mode.

And a remote electric control mode with authority limit is adopted.

Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages: the detection method of the electric hoist does not need to operate the one-stage height limiter, and can perform function detection on the two-stage height limiter through simple operation, so that the performance of the electric hoist is improved.

The invention also provides an electric hoist detection auxiliary device which has simple structure, convenient use, lower cost and higher safety, and the scheme is as follows:

The electric hoist detection auxiliary device comprises a bypass circuit capable of being connected or disconnected and shorting an electric switch bypass of the primary height limiter when the electric hoist detection auxiliary device is connected, and a change-over switch for controlling the bypass circuit to be connected or disconnected; configuring a normal operation mode and a bypass operation mode for the electric hoist; when the electric hoist is in the normal operation mode, the bypass circuit is disconnected, limiting function detection is carried out on the primary height limiter, and when the electric hoist is in the bypass operation mode, the bypass circuit is connected, and limiting function detection is carried out on the secondary height limiter.

The bypass circuit comprises a bypass relay, a normally open node of the bypass relay is connected with an electric switch of the primary height limiter in parallel, and a coil of the bypass relay is connected with a control power supply of the electric hoist after being connected with the change-over switch in series.

The change-over switch is a switch with authority limit function.

The change-over switch is arranged on a control panel of the electric hoist.

Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages: the electric hoist detection auxiliary device has the advantages of simple structure, convenient operation and use, lower cost and higher safety, and can conveniently assist in detecting the height limiter of the electric hoist.

The invention also provides an electric hoist convenient for detecting the height limiter, which adopts the scheme that:

An electric hoist comprises a first-level limiter, a second-level limiter and the electric hoist detection auxiliary device.

The electric hoist further comprises a lifting mechanism, a lifting power supply unit for supplying power to the lifting mechanism, a control system and a control power supply unit for supplying power to the control system;

The lifting power supply unit comprises a power supply main line connected with an external power supply, a lifting power supply line which is led out from the power supply main line and is connected with the lifting mechanism in a positive patch cord mode when the lifting power supply unit is connected with the lifting mechanism, and a descending power supply line which is led out from the power supply main line and is connected with the lifting mechanism in a reverse wiring mode when the lifting power supply unit is connected with the lifting mechanism, wherein a power supply main switch is connected in series in the power supply main line;

The control system comprises a rising relay, a falling relay, a rising operation switch, a falling operation switch, an emergency stop switch and a starting switch, wherein the emergency stop switch is connected with the starting switch in series and is connected with the control power supply unit, the rising operation switch is connected with a coil of the rising relay in series to form a rising control circuit and is connected with the control power supply unit, the falling operation switch is connected with a coil of the falling relay in series to form a falling control circuit and is connected with the control power supply unit, a normally open contact of the rising relay is connected in series in the rising power supply circuit, and a normally open contact of the falling relay is connected in series in the falling power supply circuit; the electric switch of the first-level height limiter is connected in series in the ascending control circuit, and the electric switch of the second-level height limiter is connected with the ascending control circuit;

The control power supply unit comprises a transformer with a primary side connected with the external power supply, and a secondary side of the transformer is connected with the control system.

The first-level height limiter is a heavy hammer type height limiter, and the second-level height limiter is a fire-cut-off type height limiter.

Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages: the electric hoist has the advantages of simple structure, convenient operation, capability of conveniently realizing the function detection of the height limiter and higher safety.

Drawings

Fig. 1 is a schematic diagram of the appearance of the electric hoist of the present invention.

Fig. 2 is a circuit diagram of the electric hoist of the present invention.

In the above figures: 1. a first housing; 2. a second housing; 3. a third housing; 4. a controller; 5. a first-stage height limiter; 6. a second-stage height limiter; 7. a rope; 8. a rope guide; 9. and the lifting appliance device.

Detailed Description

The invention will be further described with reference to examples of embodiments shown in the drawings.

Embodiment one: as shown in figure 1, the electric hoist comprises a shell, a lifting mechanism and two-stage height limiters. The lifting mechanism comprises a lifting motor and a brake thereof, a speed reducer in transmission connection with the lifting motor, a winding drum connected with the speed reducer for rotation, a rope guide 8 arranged on the winding drum and provided with a rope 7, a lifting appliance device 9 connected with the rope 7 and a control system. The control system is used for controlling the operation of the lifting motor, and is provided with a controller 4 which is connected by wire or wirelessly for personnel to operate. The housing comprises a first housing 1 for accommodating the speed reducer, a second housing 2 for accommodating the reel and the rope guide 8, and a third housing 3 for accommodating the lift motor and the brake, which may also be accompanied by an electrical box for accommodating the control system. The two-stage height limiters are a first-stage height limiter 5 and a second-stage height limiter 6 respectively, and the two-stage height limiters are connected with a control system through signals. The limiting height of the primary height limiter 5 is lower than that of the secondary height limiter 6, when the lifting mechanism acts to lift the heavy object, the primary height limiter 5 acts firstly, and the secondary height limiter 6 acts after the primary height limiter 5 fails. Typically, the primary height limiter 5 is a heavy hammer type height limiter, and the secondary height limiter 6 is a fire-cut type height limiter. The heavy hammer type height limiter mainly comprises a heavy hammer which is virtually sleeved on the rope 7, an electric switch and a pull rope which are installed near the fixed end of the rope 7, wherein two ends of the pull rope are respectively connected with the heavy hammer and the electric switch, the pull rope is pulled by the gravity of the heavy hammer to enable the electric switch to be in a closed state, and the height of the heavy hammer is the limiting height of the heavy hammer. The electric switch of the heavy hammer height limiter is connected in series in the control system, when the lifting appliance device 9 lifts to the height of the heavy hammer, the heavy hammer is pushed to lift, the pull rope does not pull the electric switch in a tensioning mode any more, the electric switch is disconnected, the control system of the lifting motor is disconnected, and the lifting motor stops rotating, so that the purpose of limiting the height at one stage is achieved. If the heavy hammer type height limiter fails, the lifting mechanism continuously drives the heavy object to rise, when the lifting appliance device 9 is lifted to the limit height corresponding to the fire-cut type height limiter, the rope guider 8 pushes or pulls the connecting rod of the electric switch of the fire-cut type height limiter through the collision block to disconnect the electric switch, so that the lifting motor is powered off to stop rotating, and the purpose of secondary height limitation is achieved. In general, the limit height corresponding to the second-level height limiter 6 is lower than the height of the electrical switch of the first-level height limiter 5, so that when the first-level height limiter 5 fails and the lifting device 9 continues to lift, the second-level height limiter 6 can limit the height before the lifting device 9 touches the electrical switch of the first-level height limiter 5, so as to protect the safety of the electrical switch of the first-level height limiter 5 and avoid damage and possible falling of the electrical switch.

The method for detecting the functions of the electric hoist with the primary height limiter 5 and the secondary height limiter 6 comprises the following steps: configuring a normal operation mode and a bypass operation mode for the electric hoist; when the electric hoist is in a normal operation mode, the limit function of the primary height limiter 5 is detected (namely, a lifting mechanism is used for lifting a heavy object, when the lifting appliance device 9 reaches the limit height corresponding to the primary height limiter 5, if the primary height limiter 5 can disconnect a control system of the lifting mechanism, the function is normal) as same as that of the existing electric hoist; when the electric hoist is in the bypass operation mode, after the electric switch bypass of the primary height limiter 5 is shorted (namely, the control system of the lifting mechanism is normally connected through the bypass short circuit), the secondary height limiter 6 is subjected to limit function detection (namely, the lifting mechanism is used for lifting a heavy object, when the lifting device 9 reaches the limit height corresponding to the secondary height limiter 6, if the secondary height limiter 6 can disconnect the power supply line of the lifting mechanism, the function is normal). The bypass short circuit of the electric switch of the first-stage height limiter 5 is realized by a remote electric control mode, and the bypass short circuit of the electric switch of the first-stage height limiter 5 is preferably realized by a remote electric control mode with authority limit, so that the electric hoist is switched between a normal operation mode and a bypass operation mode by the remote electric control mode with authority limit.

The electric hoist detection auxiliary device designed based on the technical conception of the electric hoist detection method comprises a bypass circuit and a change-over switch. The bypass circuit itself can be turned on or off, and when it is turned on, the electrical switch of the primary height limiter 5 can be bypassed and shorted, and the switch is used to control the bypass circuit to be turned on or off. When the bypass circuit is disconnected by using the change-over switch, the electric hoist is in a normal operation mode, and the limit function of the primary height limiter 5 is detected at the moment; when the bypass circuit is switched on by the change-over switch, the limit function of the secondary height limiter 6 is detected when the electric hoist is in the bypass operation mode.

The bypass circuit comprises a bypass relay, the bypass relay is provided with a coil and a normally open node, the normally open node of the bypass relay is connected with an electric switch of the primary height limiter 5 in parallel, and the coil of the bypass relay is connected with a control power supply of the electric hoist after being connected with the change-over switch in series. When the coil of the bypass relay is connected with the control power supply of the electric hoist by utilizing the switching switch to be connected, the normally open node of the bypass relay is switched from the off state to the on state, so that the electric switch bypass of the primary height limiter 5 is short-circuited. The above-mentioned change-over switch preferably employs a switch having a permission restriction function, such as a switch controlled by a mechanical key or an electronic authorization card.

Based on the scheme and referring to fig. 2, a specific scheme of the electric hoist is as follows:

The electric hoist comprises a lifting mechanism, a lifting power supply unit, a control system, a control power supply unit, a primary height limiter 5, a secondary height limiter 6 and an electric hoist detection auxiliary device, wherein the control system is provided with a controller 4 in a matched mode, and a control panel of the electric hoist is arranged on the controller 4.

The lifting mechanism comprises a lifting motor M and a brake thereof, a speed reducer in transmission connection with the lifting motor M, a winding drum connected with the speed reducer for rotation, a rope guide 8 which is arranged on the winding drum and is provided with a rope 7, a lifting appliance device 9 connected with the rope 7 and a control system. Wherein the lifting motor M can rotate forward or reversely, thereby realizing the lifting or descending of the driven weight.

The lifting power supply unit is used for supplying power to the lifting mechanism and comprises a power supply main line, a lifting power supply line and a descending power supply line. The power supply main line is connected with ABC three phases of an external power line to obtain electric energy, a fuse FU and a power supply main switch QS are connected in series on the power supply main line, and an entity of the power supply main switch QS is usually arranged in a shared or special power supply control cabinet arranged on the ground or a wall surface and used for controlling the cut-off or the cut-on of the whole loop. The ascending power supply line and the descending power supply line are both led out by a power supply main line, the ascending power supply line is connected with a lifting motor M in the lifting mechanism in a positive switching line mode when the ascending power supply line is connected with the lifting motor M in the lifting mechanism in a reverse wiring mode when the descending power supply line is connected with the lifting motor M in the lifting mechanism. The ascending power supply line and the descending power supply line are connected in parallel and then connected with the lifting motor M through the thermal relay FR.

The control system is used for controlling the hoisting mechanism, and comprises an emergency stop switch JT (usually a knob switch arranged on the controller 4), a start button QA (usually a key switch arranged on the controller 4), a lifting relay KM1, a descending relay KM2, a lifting operation switch SB1 and a descending operation switch SB2. The emergency stop switch JT and the start button QA are connected in series to form a control main line and are connected with a control power supply unit. The ascending operation switch SB1 and the coil of the ascending relay KM1 are connected in series to form an ascending control line and are connected with a control bus line, and the descending operation switch SB2 and the coil of the descending relay KM2 are connected in series to form a descending control line and are connected with the control bus line. The ascending control line and the descending control line are connected in parallel and then connected with the control bus line. The normally open contact of the rising relay KM1 is connected in series in the rising power supply line, and the normally open contact of the falling relay KM2 is connected in series in the falling power supply line, namely the normally open contact of the rising relay KM1 and the normally open contact of the falling relay KM2 are in phase-change parallel to form a rising power supply line and a falling power supply line, and then are connected with a power supply bus line. The normally closed electric switch SQ1 of the primary height limiter is connected in series in the ascending control circuit, and the normally closed electric switch SQ2 of the secondary height limiter is connected with the ascending control circuit (the electric switch SQ2 of the secondary height limiter is connected in series in the ascending control circuit, or the electric switch SQ2 of the secondary height limiter is connected on a circuit after the ascending control circuit and the descending control circuit are connected in parallel). If the lifting mechanism comprises a plurality of lifting motors M, each lifting motor M respectively provides electric energy through a corresponding lifting power supply circuit and a corresponding descending power supply circuit, and a lifting relay KM1, a descending relay KM2, a lifting operation switch SB1 and a descending operation switch SB2 are respectively arranged corresponding to each lifting motor M in the control system so as to respectively form a corresponding lifting control circuit and a corresponding descending control circuit.

The control power supply unit is used for supplying power to the control system and comprises a transformer TC, wherein the primary side of the transformer TC is connected with an external power supply, and the secondary side of the transformer TC is connected with the control system, namely, the rising power supply line and the falling power supply line are respectively connected with the secondary side of the transformer TC.

The electric hoist detection auxiliary device comprises a bypass circuit and a change-over switch K. The bypass circuit comprises a bypass relay KM3, a normally open node of the bypass relay KM3 is connected with an electric switch SQ1 of the primary height limiter in parallel, and a coil of the bypass relay KM3 is connected with a control power supply of the electric hoist after being connected with a change-over switch K in series, namely, a secondary side of a transformer TC. The change-over switch K adopts a switch with a permission limiting function.

The above-mentioned start button QA, emergency stop switch JT, up operation switch SB1, down operation switch SB2, and change-over switch K are provided on the control panel of the controller 4 of the electric hoist.

Aiming at the electric hoist with double limit, the method and the steps in the use unit personnel use spot inspection, maintenance unit personnel maintenance and safety supervision, inspection or detection mechanism personnel inspection, inspection or detection are as follows:

1. the change-over switch K with authority limit function is in a common gear/normal gear, for example, the rotary switch with a key rotates to the common gear/normal gear, and under the gear, the electric hoist is in a normal running mode;

2. The emergency stop switch JT is turned on, and the start button QA is pressed. For the lifting mechanism driven by the single lifting motor M, a lifting key is arranged on a controller of the lifting mechanism to operate a lifting operation switch SB1, the lifting operation switch SB1 is closed, a lifting control line is connected, a normally open contact of the relay KM1 is closed due to the fact that the coil of the relay KM1 is electrified, so that a lifting power supply line is connected, and the lifting motor M rotates positively to drive a heavy object to lift upwards through a lifting device 9. For the lifting mechanism driven by the double lifting motors M, two lifting keys are arranged on the controller to respectively operate the corresponding lifting operation switches SB1 (the lifting keys and the corresponding weight type height limiters are in one-to-one correspondence with the wiring), and the follow-up process is the same as the previous process. When the lifting appliance device 9 rises to a limit height corresponding to the heavy hammer type height limiter, the electric switch SQ1 is disconnected, the lifting control circuit is disconnected, the coil of the relay KM1 is powered off to disconnect the normally open contact, so that the lifting power supply circuit is disconnected, the lifting motor M stops rotating positively, and the heavy hammer type height limiter is judged to be normal in function;

3. The change-over switch K with the authority limit function is in a bypass gear, for example, a rotary switch with a key rotates to the bypass gear, under the gear, the electric hoist is in a bypass operation mode, a normally open contact of the bypass relay KM3 is closed by electrifying a coil of the bypass relay KM3, an electric switch SQ1 of the heavy hammer type height limiter is in bypass short circuit, and a lifting control circuit is connected; if the lifting mechanism comprises a plurality of lifting motors M, after lifting control circuits corresponding to the lifting motors M are connected in parallel, the lifting control circuits are commonly connected to an electric switch SQ1 of a heavy hammer type height limiter and a normally open node of a bypass relay KM3 attached with the heavy hammer type height limiter, so that bypass short circuit of one change-over switch K and one bypass relay KM3 for controlling a plurality of lifting control circuits can be realized;

4. The lifting motor M rotates positively to drive the heavy object to continuously lift upwards through the lifting device 9, when the lifting device 9 rises to the limit height corresponding to the fire-cut height limiter, the electric switch SQ2 of the lifting device is disconnected to enable the lifting relay KM1 to lose electricity, so that the lifting power supply line is disconnected, the lifting motor M is powered off to stop rotating positively, and the fire-cut height limiter is judged to be normal in function; for a lifting mechanism with a plurality of lifting motors M, the fire-cut-off type height limiter can cut off the lifting relay KM1 corresponding to each lifting motor M;

5. after the function inspection of the fire-cut-off type height limiter is finished, the bypass circuit is returned to the common gear/normal gear by utilizing a change-over switch K with a permission limiting function;

6. and finishing the inspection of the height limiter of the electric hoist.

On the basis of the scheme, the bypass circuit further comprises a buzzer H and/or a flash lamp L connected in series with the normally open node of the bypass relay KM3, and then the normally open node of the bypass relay KM3 is closed in the bypass working mode, and the buzzer H and/or the flash lamp L send out sound and/or light alarm signals.

The scheme can conveniently and safely carry out related inspection on the electric hoist by remotely and electrically controlling the electric switch bypass short circuit of the primary height limiter of the electric hoist, is used for exploring the bypass mode of the safety protection device of the lifting mechanism in the field of lifting machinery, and is also an important technical breakthrough point of the normal daily use point inspection, maintenance and inspection of the lifting mechanism and the safety inspection, inspection or detection working method.

The above embodiments are provided to illustrate the technical concept and features of the present invention and are intended to enable those skilled in the art to understand the content of the present invention and implement the same, and are not intended to limit the scope of the present invention. All equivalent changes or modifications made in accordance with the spirit of the present invention should be construed to be included in the scope of the present invention.

Claims (10)

1. The utility model provides an electric block detection method for carry out function detection to electric block that has first-level high stopper and second-level high stopper, its characterized in that: the electric hoist detection method comprises the following steps: configuring a normal operation mode and a bypass operation mode for the electric hoist; when the electric hoist is in the normal operation mode, limit function detection is carried out on the primary height limiter, and when the electric hoist is in the bypass operation mode, limit function detection is carried out on the secondary height limiter after the electric switch bypass of the primary height limiter is in short circuit.

2. The method for detecting the electric hoist according to claim 1, characterized in that: and the bypass short circuit of the electric switch of the primary height limiter is realized in a remote electric control mode.

3. The method for detecting the electric hoist according to claim 2, characterized in that: and a remote electric control mode with authority limit is adopted.

4. The utility model provides an electric block detects auxiliary device, sets up in the electric block that has first-level high stopper and second-level high stopper, its characterized in that: the electric hoist detection auxiliary device comprises a bypass circuit capable of being connected or disconnected and shorting the electric switch bypass of the primary height limiter when being connected, and a change-over switch for controlling the bypass circuit to be connected or disconnected; configuring a normal operation mode and a bypass operation mode for the electric hoist; when the electric hoist is in the normal operation mode, the bypass circuit is disconnected, limiting function detection is carried out on the primary height limiter, and when the electric hoist is in the bypass operation mode, the bypass circuit is connected, and limiting function detection is carried out on the secondary height limiter.

5. The electric hoist detection assisting device according to claim 4, characterized in that: the bypass circuit comprises a bypass relay, a normally open node of the bypass relay is connected with an electric switch of the primary height limiter in parallel, and a coil of the bypass relay is connected with a control power supply of the electric hoist after being connected with the change-over switch in series.

6. The electric hoist detection assisting device according to claim 4, characterized in that: the change-over switch is a switch with authority limit function.

7. The electric hoist detection assisting device according to claim 4, characterized in that: the change-over switch is arranged on a control panel of the electric hoist.

8. The utility model provides an electric block, includes first-level high stopper and second-level high stopper, its characterized in that: the electric hoist further includes the electric hoist detection assisting apparatus according to any one of claims 4 to 7.

9. The electric block of claim 8, wherein: the electric hoist further comprises a lifting mechanism, a lifting power supply unit for supplying power to the lifting mechanism, a control system and a control power supply unit for supplying power to the control system;

The lifting power supply unit comprises a power supply main line connected with an external power supply, a lifting power supply line which is led out from the power supply main line and is connected with the lifting mechanism in a positive patch cord mode when the lifting power supply unit is connected with the lifting mechanism, and a descending power supply line which is led out from the power supply main line and is connected with the lifting mechanism in a reverse wiring mode when the lifting power supply unit is connected with the lifting mechanism, wherein a power supply main switch is connected in series in the power supply main line;

The control system comprises an ascending relay, a descending relay, an ascending operation switch and a descending operation switch, wherein the ascending operation switch is connected with a coil of the ascending relay in series to form an ascending control circuit and is connected with the control power supply unit, the descending operation switch is connected with a coil of the descending relay in series to form a descending control circuit and is connected with the control power supply unit, a normally open contact of the ascending relay is connected in series in the ascending power supply circuit, and a normally open contact of the descending relay is connected in series in the descending power supply circuit; the electric switch of the first-level height limiter is connected in series in the ascending control circuit, and the electric switch of the second-level height limiter is connected with the ascending control circuit;

The control power supply unit comprises a transformer with a primary side connected with the external power supply, and a secondary side of the transformer is connected with the control system.

10. The electric block according to claim 8 or 9, characterized in that: the first-level height limiter is a heavy hammer type height limiter, and the second-level height limiter is a fire-cut-off type height limiter.