JPS6040166B2 - Electric operation mechanism for tap changer under load - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an electric operating mechanism for a tap changer on load,
In particular, the present invention relates to an electric operating mechanism for a tap changer on load that is configured to prevent the tap from running out of control due to either electrical or mechanical failure.

The known electric operation mechanism for tap switching on load includes two electromagnetic contactors for switching the tap of the transformer tap winding in the step-up and step-down directions, and a step for mechanically detecting the completion of the tap switching. Equipped with a forward switching switch. In such devices, when the electromagnetic contactor becomes unable to return due to the contact sticking and sticky material generated between the movable and fixed iron cores, or when the stepping switch is mechanically damaged when changing the tap. When the switching operations become impossible or when these operations overlap, the tap becomes out of control. In this case, the tap reaches its limit, causing tap misalignment between phases, which causes an overcurrent relay to operate, tripping the power supply and causing a major accident.Therefore, it is desired to have a system that can prevent tap runaway. Although there is no known example regarding this technology, it is technically conceivable that the tap switching time is performed within a certain period of time. There is a way to detect this and open the motor circuit.

This method has a low level of protection because it detects the occurrence of a lock switching operation, that is, a state in which the tap switching operation has run out of control, and opens the motor circuit to prevent the accident. This invention was made to satisfy these demands, and it is possible to improve electrical and mechanical performance by roughly combining a normally open contact of a buck-boost magnetic contactor, a cam switch that operates after tap switching is completed, and a runaway prevention magnetic contactor. An object of the present invention is to provide an electric operating mechanism for a tap changer under load that can prevent tap runaway even if any of the failures occur.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

Fig. 1 is an operating circuit diagram of the tap switching motor, Fig. 2 is a tap switching control circuit diagram equipped with a tap runaway prevention circuit, Fig. 3 is a tap runaway detection circuit, and Fig. 4 is the operation of cam switches 33SR and 33SL. It is an explanatory diagram.

Figure 1 shows the operating circuit, and in the figure R, S, T
is the power supply terminal, 88 is the no-fuse disconnector, 88A-1
~88A-3 is a normally closed contact of the runaway prevention electromagnetic contactor 88A.

88R-1 to 88R-3 and 88L-1 to 88L-3
are connected in parallel to each other through the normally open contacts of the voltage step-up and step-down electromagnetic contactors 88R and 88L, and only the R and S phases are reversely connected in order to rotate the tap-cutting electric motor in the step-up or step-down direction.

88M is a tap-cutting electric motor for driving a tap-cutting machine (not shown) under load. Next, the tap-sliding control circuit shown in FIG. 2 will be explained. 88R and 88L', electromagnetic contactors 33R and 33L that rotate the electric motor 88M in the step-up and step-down directions are limit switches that open at the tap upper limit or lower limit position, 88A are electromagnetic contactors for preventing tap runaway, 7R and 7L. is a selection switch for field operation, -3
3S is a conversion switch that is activated by an energy storage device (not shown) upon completion of tap switching, 33SX-1 and 2 are step-by-step latching relays that compensate for step-by-step operation, and 7RX and 7LX are automatic switches that are installed in a control panel (not shown). This is an auxiliary relay that receives signals from a voltage regulator and provides step-up and step-down signals.

33SR and 33SL are cam switches that are opened and closed by the rotation of the electric motor 88M.As shown in FIG. It opens and closes between the stop range RS and the mountains in the pressure decreasing direction.

The part indicated by the dotted line in FIG. 2 is a connection diagram inside the control panel, and the solid line part is a connection diagram of the motor operating mechanism. In FIG. 2, terminals R' and T' are control power supply terminals connected to control buses A and B, respectively. Terminals 1, 2, 3, and 4 are necessary for connection to the control panel. Thus, the electromagnetic contactors 88R and 88L' are electrically interlocked and connected by the normally closed contacts 88R-6 and 88L-6, respectively. The contacts of control switches 33R and 33L were connected to normally open contacts 7RX-2 and 7LX-2 of auxiliary relays 7RX and 7LX via terminals 3 and 4, and one was connected to control bus A of magnetic contactors 88R and 88L. After connecting in parallel with the self-holding contacts 88R-4 and 88L-4, it is connected to the coils of the electromagnetic contactors 88R and 88L. The other of the normally open contacts 7RX-2 and 7LX-2 are connected in parallel and connected to bus bar A via terminal 1. Selection switch 7R, 7
The L contacts 7R-1 and 7L-1 are connected at one end to the terminals 3 and 4, respectively, and the ends are connected in parallel, and then connected to the bus A to form a signal circuit.

Normally closed contact 88R-6, 88 of electromagnetic contactor 88R, 88L
After connecting L-6 in parallel, latching relay 33SX-
Terminal c and a, b of switching contact 12C-1 of 1 and 2
As shown in the figure, it is connected to the contacts 33S-1 and 33S-2 of the conversion switch 33S, and then connected to the bus B.

The coils of the stepping latching relays 33SX-1 and 33SX-1 and 2 connect one end to the bus bar B via the contacts 33S-1 and 2 of the switching switch 33S, and the coils connect the coils to the bus bar B via the contacts 33S-1 and 2 of the switching switch 33S. Normally open contacts 88 of contactors 88R and 88L
L-7, 88R-7, normally closed contacts 7R-2, 7L-2 of selection switches 7R, 7L, and furthermore, normally closed contacts 7LX-1 of auxiliary joint fin devices 7RX, 7LX in the control panel via terminal 2. ,7RX
-1 are connected in series and connected to bus A through terminal 1 to form a step circuit. The stepping latching relay 33SX is 2
There are two coils 33SX-1 and 33SX-2 and two sets of switching contacts 12C-1 and 12C-2 operated by one coil, each switching contact configured to remain in the operated position. There is. To explain the operation in FIG. 2, the two sets of switching contacts 12C-1 and 82C-2 are in the illustrated position.
When the conversion switch 33S changes from this state and switches from 33S-2 to 33S-1, the coil 3 of the latching relay
3SX-1 is energized via its switching contact V2C-2. Due to the excitation, the switching contact is switched from terminal b to terminal a, and at the same time, the excitation circuit of the coil 33SX-1 is opened and the switching operation is completed. As a result, the two sets of sliding contacts are held at their respective a terminals. Conversely, when the coil 33SX-2 is energized, it operates in the same manner, and the switching contacts are held at their respective b terminals, waiting for the next switching signal (FIG. 2). The tap runaway prevention circuit connects the normally open contact 38R-5 of the electromagnetic contactor 88R and the cam switch 33SR in series.
After the normally open contact 88L-5 of L and the cam switch 33SL are connected in series, both are connected in parallel, and one end of this is connected in series to one end of the coil of the runaway prevention electromagnetic contactor 88A.

Also, the terminal of the coil 88A is connected to the bus B. moreover,
Normally open contacts 88R-8, 88 of electromagnetic contactors 88R, 88L
After connecting L-8 in parallel, one end of the L-8 is connected to one end of the 88A coil via an 88A self-holding contact 88A-4 to form a self-holding circuit of the runaway prevention electromagnetic contactor 88.
Next, the tap runaway detection circuit shown in FIG. 3 will be explained.

Simultaneously with the start of tap runaway, the runaway prevention electromagnetic contactor 88A operates. In order to detect this, one end is energized by a normally open contact 88A-5 connected to the bus line A', and one end is connected to the bus line B'.
A detection time relay 66 is provided connected to. The normally open contact 66-1 of the time relay 66 closes after a certain period of time, and has one end connected to the bus A', the other end connected in parallel to an indicator lamp PL and a buzzer BZ, and then connected to the bus B'. The operation of the cam switch in such a configuration will be explained with reference to Fig. 4.There are several dozen types of tap points in a transformer other than the standard 17 points, but the operation of the cam switch is related to the number of tap points. Since the opening/closing operation is repeated according to the number of tap points, here, the reciprocation of tap instructions 1 to 4 will be explained. Note that the tap instructions 1, 2, etc. in Fig. 4
. . . n indicates the tap position of the on-load tap switching transformer. In Fig. 4, c is in the direction of increasing the voltage of the conversion switch 33S (tap instructions 1, 2, 3, 4,...
d shows the operation sequence when switching from tap instruction 4 to the step-down direction (tap instruction n, ..., 4, 3, 2, 1 direction). be.

Further, e and f are diagrams showing the operating order of the pressure increasing direction cam switches 33SR and the pressure decreasing direction cam switches 33SR and 33SL.

At the same time as the tap switching is completed, the conversion switch 33S operates, the Sagishige contactor 88R or 88L returns, and the motor circuit is opened.
The electric motor 88M idles by x rotations and stops in the range Y due to the load and friction of the bearing. Ranges RS and LS indicated by two-dot chain lines in the figure indicate the stop range Y of the electric motor when switching in the step-up and step-down directions. Cam switch 33SR, 3
Two sets of 3SLs having exactly the same structure are provided (one set for the voltage boost direction and one set for the voltage drop direction). Operation is conversion switch 33S
In the range Y, where the motor is delayed by a rotation from the operating point of , and the motor is closed during b rotations, the motor is stopped. Here, a is designed to cover the time from the operation of the conversion switch 33S until the normally open contacts 88R-5 and 88L-5 of the electromagnetic contactors 88R and 88L are connected, and b is a runaway prevention electromagnetic contactor 88A.
Adjust so that it remains closed for a period of time until it operates and self-holds. Next, the operation during normal cutting from tap 1 to tap 4 will be explained. The electric motor 88M rotates from the stop range Y on the left side of the tap instruction 1 to the boost direction tap instruction 2. This rotation closes the cam switch 33SL. However, since 88L-5 is open, the runaway prevention electromagnetic contactor 88A does not operate. When switching to tap instruction 2 is completed, the conversion switch 33S switches, and after a rotation from its operating point, the cam switch 33SR
operates and opens after rotation b. On the other hand, the electric motor 88M idles by rotating x and stops. Similarly, repeat the same operation as tap instructions 3 and 4. Next, a case where the tap instruction 4 is reversed and switched to the tap instruction 1 will be described. Stop position for tap instruction 4 The eagle is stopped at RS of tap instruction 4.

When switching from this position to the direction of tap instruction 1,
"The cam switch 33SU passes the normal position of tap instruction 3, rolls a, and stops in the range b ("black area" in the figure).
This completes the switch to tap instruction 3. Then, the conversion switch 33S operates, and after a rotation from its operating point, the cam switch 33SL operates, and after a rotation b, the electric motor idles for X rotations and then stops. Similarly, tap instruction 2,
Repeat step 1. This will be explained below using the sequences shown in FIGS. 1 to 3. Power terminals R, S. T,R,
A predetermined power is supplied to T', R'', and T''. Also, the no-fuse circuit breaker 88 is turned "ON". Then, the electromagnetic contactor 88R (88R) receives a switching signal from the auxiliary relay 7RX (7LX), which operates in response to a signal from an automatic voltage regulator in the control panel (not shown), or the selection switch 7R (7L) for on-site operation.
L) operates and its normally open contacts 88R-1, 2, 3 (88
L-1, 2, 3) are closed and the motor 88M is rotated in the voltage increasing (decreasing) direction.

At the same time, a self-holding circuit is formed by the normally open contact 88R-4 (88L-4). Also, normally open contact 8 in the runaway prevention circuit.
8R-5 (88R-5) and 88R-8 (88L-8
) is closed, but the runaway prevention electromagnetic contactor 88A does not operate because the cam switch 33SR (33SL) is engaged. Furthermore, the normally closed contact 88R-7 (88L-7) becomes closed and opens the circuit of the latching relays 33SX-1 and 33SX-2. When the tap switching is thus completed, the conversion switch 33S is reversed and its movable contact is switched from the fixed contact 33S-2 to the fixed contact 33S-1. The operation of the conversion switch causes the electromagnetic contactor 88R (88L
) returns to normal open contact 88R-1, 2, 3 (88L-
1, 2, and 3) open, the motor idles X rotations and stops. When the normally open contact 88R-7 (88L-7) returns, the coil 33SX-1 of the latching relay 33SX is energized via its own switching contact 12C-2, and this energization causes the switching contact 12C-2 to switch to terminal b. Switching from to a completes preparations for waiting for the next switching command. On the other hand, the runaway prevention circuit opens after the normally open contact 88R-5 (88L-5) opens.
Since SR (33SL) is closed, the runaway prevention electromagnetic contactor 88A does not operate during normal operation.

The above has explained the operation during normal operation, but next we will discuss the case where the electromagnetic contactor 88R (88L) cannot be reset or the conversion switch 33S is mechanically damaged and the sliding door operation becomes impossible. explain.

Auxiliary relay 7RX (7LX) or selection switch 7R (7L
) In response to the command, the electromagnetic contactor 88R (88L) operates, rotates the electric motor 88M in the voltage step-up (step-down) direction, and starts tap switching operation.

If the conversion switch 33S is mechanically damaged and cannot be reversed when the tap change is completed, the excitation circuit of the magnetic contactor 88R (88L) will not be released and will remain energized. . In addition, even if the conversion switch 33S operates normally, if the electromagnetic contactor 88R (88L) cannot be reset due to welding of its contacts or adhesive foreign matter generated between the movable and fixed cores, the electromagnetic contactor 88
R, 88L' becomes operational. As mentioned above, even in the case of misalignment, the electromagnetic contactor 88R (88L) is in the operating state, and its normally open contacts 88R-1 to 5, 8 (88L-1 to 5, 8) are closed.
The normally closed points 88R-6, 7 (88L-6, 7) remain open, leading to tap runaway and reaching the tap limit.

In this way, as a way to prevent "tap runaway", if the switching operation starts from tap instruction "1", the point at which the switching operation ends at tap instruction "2", that is, the contact point of the conversion switch 33S. 33S-2 to 33S-
After passing the point where it switches to 1, turn the cam switch 3 with a rotation.
3SR (33SL) closes and electromagnetic saddle contactor 88A to prevent runaway
operates, and the circuit of the electric motor 88M is opened by the terminals 88A-1 to 88A-3 to prevent tap runaway. In addition, a self-holding circuit is formed by the contact 88A-4, and the electromagnetic contactor 88R (88L
) continues to operate while it is in the operating state. here,
After the electric motor 88M is disconnected from the circuit by the runaway prevention electromagnetic contactor 88A, it stops within the stop range Y as in normal operation, and stops at exactly the same position as in normal operation. The operation described above prevents the tap from running out of control, operates the time relay 66 using the contact 88A-5, and after a certain period of time has elapsed, the monitor is notified by the display lamp PL and the buzzer BZ.

Note that in the explanation, the part in parentheses indicates the operation when switching the voltage step-down direction.

As described above, the following effects are produced by providing the tap runaway prevention circuit constituted by the cam switches 33SR and 33SL that operate immediately after tap switching and the tap runaway prevention electromagnetic contactor 88A of the present invention.

{1} Any electrical or mechanical failure, such as the inability of the electromagnetic contactors 88R and 88L to return due to stuck or movable contacts or foreign matter generated between the fixed cores, or the inability to switch due to mechanical damage to the switching switch 33S. Even if an accident occurs, the cam switches 33SR and 33SL detect the above accident condition immediately after the tap is cut, and the electromagnetic contactor 88A for preventing runaway causes the motor 8 to
When opening the 8M power supply, the tap will never go out of control. [2] Since tap runaway is prevented immediately after the tap is switched, and the tap is stopped at the same time as normal switching, accidents can be prevented from occurring.

Furthermore, in the embodiment of the present invention, tap runaway is detected immediately after the switching operation is performed, and the state is maintained in the same state as during normal switching.This is a proposal with a higher level of protection than the conventional technology. be. {3} The above effects produce a ripple effect that enables the provision of an electric operating mechanism for an on-load tap changer used in a highly reliable power system.

[Brief explanation of the drawing]

Fig. 1 is an operating circuit diagram of the tap changing motor of the device of the present invention, Fig. 2 is a tap disconnection control circuit diagram of the same device, Fig. 3 is a tap runaway detection circuit diagram of the same device, and Fig. 4 is the same. FIG. 3 is a diagram for explaining the operation of a cam switch of the device. 88R, 88L...magnetic contactor for voltage step-up and step-down,
33SR, 33SL. ...Rikimusuichi, 88A
...Magnetic contactor for runaway prevention, 88M...
・Electric motor for tap changer. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. In an electric operating mechanism for an on-load tap changer in which the on-load tap changer is driven by an operating electric motor, a mechanism is connected between the control power source of the operating electric motor, and the electric operating mechanism is operated by the rotation of the operating electric motor immediately after tap switching is completed. Connect the series circuit of the cam switch and the electromagnetic contactor for preventing tap runaway, connect the electromagnetic contactors for tap boosting and bucking in parallel to this series circuit, and make sure that the electromagnetic contactors for tap boosting and bucking are operating normally. An auxiliary contact that opens earlier than the cam switch closes when the cam switch is closed and opens the circuit of the cam switch is inserted into the series circuit to constitute an excitation circuit for the electromagnetic contactor for preventing tap runaway, and a tap booster is provided in the excitation circuit. , constitutes a self-holding circuit of the electromagnetic contactor for preventing tap runaway that is formed when the step-down electromagnetic contactor is activated, and is connected in series with the power supply circuit of the operating motor when the electromagnetic contactor for preventing tap runaway is energized. An electric operating mechanism for a tap changer when loaded, configured to open the contact of an electromagnetic contactor inserted in the tap runaway prevention.