KR910005298Y1 - Safety devices of a.c elevator - Google Patents

Abstract

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Description

AC Elevator Safety Device

1 to 3 show the alternating current elevator safety device of the present invention.

2 is a detailed circuit diagram of the current detection circuit of FIG.

3 is a start stopping circuit diagram.

4 is a configuration diagram showing a safety device of a conventional AC elevator.

* Explanation of symbols for main parts of the drawings

R. S. T: Three-Phase AC Power Source: Three-Phase Induction Motor

2-2F: Power control element 3a, 3c: Contact point (main contactor contact point)

4: current transformer 10: elevator car

17a: starting stopping circuit (current detection relay contact)

This invention relates to a device for confirming the safety of an alternating current elevator using a power control element, in particular for the safety at startup.

4 is a block diagram showing a safety device of a conventional AC elevator shown in Japanese Patent Laid-Open No. 60-19675.

In the figure, RST is a three-phase AC power supply, 1 is a three-phase induction motor that is powered by an AC power supply RST to drive an elevator car (hereinafter, abbreviated as illustrated below), and 2A and 2B are connected in reverse parallel to each other. Power control elements of thyristors connected to the same, 2E and 2F are power control elements connected to the power supply T in the same manner, and 3a-3c are normally open contacts of the main contactor 3 (described later), which are closed at startup, and 4 is a power supply. As a current transformer inserted into S phase, 4a is an output current circuit, 5 is a current detection circuit connected to the current transformer 4 to control the operation of the contacts 3a-3c.

The safety device of the conventional AC elevator is configured as described above, and the contacts 3a-3c are closed in the state where the power control elements 2A, 2B, 2E, and 2F are turned off at start-up.

At this time, the power control elements 2A, 2B, 2E, and 2F block power clearly, and the current detection circuit 5 does not operate because the output 4a of the current transformer 4 is zero.

Here, by gradually widening the control angles of the power control elements 2A, 2B, 2E, and 2F, the electric motor 1 is started and the operation of the car is started.

When the contacts 3a-3c are closed, if the power control capacity is lost in the power control elements 2A, 2B, 2E, and 2F, current flows in the electric motor 1, so that the current transformer ( 4 generates an output 4a so that the current detection circuit 5 operates.

By the way, the contacts 3a to 3c are immediately opened so that the car does not start and enters the stopped state.

As described above, in the safety device of the conventional AC elevator, when the power control element is also inserted into the power supply S phase in order to improve the control characteristics of the motor 1 or to reduce vibration noise, the power control elements 2A and 2B on the RT are provided. There was a problem that the failure of the conduction of (2E) (2F) could not be detected.

In addition, when two current transformers are used to detect currents in the R phase and the S phase, for example, all conduction failures can be detected, but there is a problem that the cost increases.

The present invention has been made to solve the above problems, and the object of the present invention is to provide a safety device for an AC elevator, which is capable of detecting a failure of the electric power control element of all phases by using only one current transformer. have.

The safety device of the AC elevator of this design adds the two-phase current of three phases in the opposite direction, detects it in the current transformer, and closes the contact of the motor circuit when the power control element is given a command of less than a predetermined conduction angle. When the current below the stationary position is detected, the contact is opened.

In this design, when conduction failure occurs between two phases in which the current transformer is inserted, the current detected by the current transformer is twice the current flowing in the two phases, and in the case where conduction failure occurs in two phases other than the two phases, The current flowing in the other two phases is obtained.

1 to 3 show an embodiment of the present invention, in which FIG. 1 is a configuration diagram, FIG. 2 is a detailed circuit diagram of a current detection circuit, and FIG. 3 is a start blocking circuit diagram, and the same parts as in the conventional apparatus are the same. It is indicated by the symbol.

Types 2C and 2D are power control elements made of thyristors connected in parallel with each other in parallel and connected to power supply S, and 2G and 2H are identically between the power supply S phase and the contact 3c, and 2I and J are the same as the power supply T phase. The power control element connected between the contact and the contact 3b, 8 is a composition pulley of the hoisting machine driven by the electric motor 1, 9 is wound on the pulley 8, and the car 10 and the counterweight 11 are provided at both ends. The main rope coupled, 12 is a brake drum coupled to the side of the electric motor 1, 13 is installed to face the outer periphery of the brake drum 12, the brake drum 12 to the braking force by the elasticity of the spring (not shown) A brake shoe to be applied, 14 is a brake coil that separates the brake shoe 13 from the brake drum 12 in opposition to the elasticity of the spring, 15 is a DC power supply for supplying power to the brake coil 14, and 16 is a direct current ( +) Power, 17 is current detection relay, 17a, 17b is its normally closed contact, 17c is its positive The standard open contact, 19a, 18b is the main contactor input relay contact that closes when the main contactor instruction comes out, 19 is the call command relay contact that opens when the thyristor gate call command is issued, 20 is a transistor, and 21 is a brake open condition. The brake condition circuit to be conducted, 22 is a brake open prevention command relay, 22a is its normal open contact, 23 is a memory circuit, and (+) (-) is a DC power supply. As shown in Fig. 1, the current transformer 4 detects the current of the S phase by adding the current of the T phase, and reverses the current direction of the S phase.

Next, the operation of this embodiment will be described.

It is assumed that the power control elements 2A-2J are in the cutoff state at the start.

When two contactor input commands are issued, the contacts 18a and 18b are closed. At this time, if both of the power control elements 2A- 2J reliably block the power, since the output 4a of the current transformer 4 is " L ", the transistor 20 is not conducting and the current detection relay 17 Does not work.

Therefore, the main contactor 3 is operated and the contacts 3a-3c are closed by the circuit of (+)-(18a)-(17a)-(3)-(-).

When the brake opening condition is established, the brake opening command relay 22 is activated by the circuit of (+)-(21)-(17b)-(22)-(-) to close the contact 22a.

Due to this, the brake coil 14 is operated and the brake shoe 13 is disengaged from the brake drum 12.

At the same time, a call command is issued to open the contact 19.

Then, for example, since the conduction angle of the power control elements 2A to 2F gradually widens, the electric motor 1 starts and the driving of the car 10 is started.

Next, when the contacts 18a and 18b are closed, the current transformer 4 gives an output 4a if a conduction failure occurs even though a cutoff command is issued to the power control elements 2A to 2F. At this time, when conducting on the S-T phase, the current transformer 4 detects both the current flowing in the S phase and the T phase, and thus detects twice the value of the current flowing in the S-T phase.

In addition, if it conducts on R-T or R-S, the current transformer 4 detects the current value which flows in each R-T phase or R-S phase as it is.

In this way, when the output 4a of the current transformer 4 becomes " H ", the transistor 20 is turned on to operate the current detection relay 17 (see FIG. 2), and thus the normally closed contacts 17a and 17b. ) Is open, and the normally open contact 17c is closed. Since the main contactor 3 is blocked by the opening of the normally closed contact 17a (see FIG. 3), the contacts 3a to 3c are opened.

In addition, since the brake opening prevention relay 22 is also occupied by opening the normally closed contact 17b (see FIG. 3), the contact 22a is opened to cut off the current in the brake coil 14 (see FIG. 1). .

For this reason, the brake shoe 13 is pressed by the brake drum 12 by the elasticity of the spring to act as a braking force.

In addition, the closing of the normally open contact 17c is stored in the memory circuit 23 (see FIG. 3). When the memory circuit 23 operates, the contacts 18a and 18b are opened to operate the main contactor 3. It is not supposed to.

In this way, when the output 4a of the current transformer 4 becomes "H" between the closing of the contacts 18a and 18b at the start to the generation of the firing command, the main contactor 3 and the brake opening prevention command relay The operation of (22) is inhibited, and detection by the current transformer 4 becomes possible even if any phase power control element 2A- 2J loses the power saving capability.

A method of detecting the blocking ability or the loss of control capability of the power control element, wherein in the above-described embodiment, when the conduction angle of the power control element at startup is equal to or less than a predetermined value, You may also

The motor 1 is subjected to direct current braking by the power control elements 2A to 2J when the car 10 is stopped in the same manner as in the conventional apparatus in normal startup.

That is, for example, the power control elements 2A, 2B, 2D, 2G, 2E, and 2J are used to constrain the power control elements 2A, 2H, 2F, and 2I.

This results in S- (4)-(2c)-(3b)-(1)-(3c)-(2F)-(4) -T and T- (4)-(2I)-(3b)-(1) The current flows through the circuit of-(2H)-(4) -S, and a DC braking force is applied to the motor 1.

As described above, in this design, the current is detected in the current transformer by adding the two-phase current of the three phases in the opposite direction, and the elevator operation is started when the current is detected below the predetermined value by giving the power control element a predetermined conduction angle. Since only one current transformer is used, it is possible to detect the failure of the power control element of all phases, thereby securing the safety of the elevator.

Claims (1)

A power control element inserted in each phase between a three-phase AC power supply and an induction motor for driving an elevator car, connected in series with a contact, a current transformer for adding and detecting currents in two phases of the three phases in opposite directions; And a start-stop circuit for opening the contact when the current transformer detects a current below a predetermined value when the contact is closed in a state in which a command of less than a predetermined conduction angle is given to the alternator.