JPS6334616B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a switching switch for a load tap changer using a vacuum switch as a switching element.

There are three main conditions that must be considered when applying a vacuum switch to a switching switch:

(i) The contacts of vacuum switches are made of arc-resistant alloys, so they have high contact resistance and are not suitable for continuous energization during non-tap switching.

(ii) In the unlikely event that a vacuum leak occurs in the vacuum switch and the switch cannot be shut off, this must be detected immediately to prevent it from developing into a short circuit between taps.

(iii) Since the dielectric strength between the contacts that are opened in a vacuum is relatively low, it is necessary to prevent the electrical discharge caused by abnormal voltage from developing into a short circuit between the taps.

The present invention has been made in order to provide a vacuum switch type changeover switch that satisfies the above conditions and has high practical reliability.

FIG. 1 shows an embodiment of the present invention, showing the configuration of a switching switch for one phase. 1 indicates a part of the tap winding of a transformer, 2 is one of the odd taps provided thereon, and 3 is one of the even taps. 4 is the main fixed contact for energizing odd number taps, 5
are main fixed contacts for energizing even-numbered taps, which are connected to odd-numbered taps 2 and even-numbered taps 3 via tap selectors (not shown), respectively. Reference numeral 6 denotes a resistor fixed contact for energization, which is connected to the odd-numbered tap 2 via a current limiting resistor 7. 8 is a main floating contact for energizing odd-numbered taps, and is connected to odd-numbered taps 2 via a vacuum switch 9 for odd-numbered taps. 10 is a main floating contact for even-numbered taps, which is connected to even-numbered taps 3 via a vacuum switch 11 for energizing even-numbered taps. Reference numeral 12 denotes a floating contact for energization, which is connected to the fixed resistor contact 6 for energization via a vacuum switch 13 for resistor. Reference numeral 14 denotes a common fixed contact for power supply, which is connected to the output terminal 15. 16 is a movable roller contact,
The contacts 4, 6, 5, and 14 are used as orbits to roll from an odd tap position (solid line) to an even tap position (broken line), or in the opposite direction. Floating contacts 8, 10, 12
is higher than the raceway surface by a certain amount and has a spring (not shown) behind it, so that when the movable roller contact 16 passes, it is pushed up to the raceway surface and maintains contact. Vacuum switches 9, 11, 13 are opened and closed by the same drive source that drives movable roller contact 16 and by another mechanism (not shown).

FIG. 2 shows the mutual relationship between the opening/closing order of the movable roller contact 16 and the energizing common contact 14 and the opening/closing order of the vacuum switches 9, 11, 13 with respect to the fixed contacts 4, 6, 5 and floating contacts 8, 10, 12. It is a sequence diagram in which relationships are collectively summarized with the horizontal axis representing travel (or time).

To switch from odd tap 2 to even tap 3,
If you read the diagram from left to right, this is the opening/closing order of each contact, and conversely, when switching from even tap 3 to odd tap 2, if you read the diagram from right to left, that is the opening/closing order of each contact. When switching from odd-numbered taps to even-numbered taps, the main fixed contact 4 for energizing the odd-numbered taps opens before the vacuum switch 9 for the odd-numbered taps is opened, so that no arc occurs. Since the main floating contact 8 for energizing odd-numbered taps opens after the vacuum switch 9 for odd-numbered taps opens, no arc occurs. That is, the vacuum switch 9 is responsible for interrupting the current accompanied by the generation of an arc. Similarly, since the energizing resistor fixed contact 6 opens before the resistor vacuum switch 13 opens, no arc occurs.

Since the current-carrying resistance floating contact 12 opens after the vacuum switch 13 finishes cutting off the current, no arc occurs. That is, in this case as well, the vacuum switch 13 is solely responsible for interrupting the current that occurs when arcing occurs.

Conversely, when switching from an even-numbered tap to an odd-numbered tap, the main fixed contact 5 for the corner tap current opens before the even-numbered tap vacuum switch 11 opens, so no arc occurs. The main floating contact 10 for even-numbered taps is connected to the vacuum switch 1 for even-numbered taps.
1 opens after the current has been cut off, so no arc occurs. In other words, in this case as well, vacuum switch 1
Only No. 1 interrupts the current with the occurrence of an arc. Instead, for continuous energization in a fixed position, the main fixed contact 4 for odd-numbered energization works with the movable roller contact 16 to bypass the vacuum switch 9 at odd-numbered taps, eliminating the need for continuous energization by the vacuum switch 9. It is said that Similarly, for even number taps, the vacuum switch 11
The main fixed contact 5 for energizing even-numbered taps bypasses the movable roller contact 16 in cooperation with the movable roller contact 16, making continuous energization of the load current unnecessary.

Also, if an abnormal voltage occurs between the odd tap 2 and the even tap 3 during testing or operation of the transformer, the voltage will not be applied across the opening gap of the vacuum switch 9 or 11. The gap between the floating contacts 8 and 10 acts in series with this, so that discharges do not easily occur. There is also a gap of fixed contacts 5 and 6 in parallel with the above-mentioned gap, which can also have a large dielectric strength regardless of the dielectric strength of the gap between the electrodes of the vacuum switch.

If the vacuum switch 9, 11 or 13 causes a vacuum leak and fails to cut off the current, an arc will occur between the floating contact 8, 10 or 12 and the movable roller contact 16, causing Since the oil pressure increases rapidly, this can be immediately detected by a hydraulic relay (not shown) or the like, and a short circuit between the taps can be prevented by tripping the main circuit breaker. On the contrary, vacuum switch 9,1
If electrode 1 or 13 is damaged and tap switching is performed while it is in an open state, an arc will occur between fixed contact 4, 5 or 6 and movable roller contact 16. Processes similar to those described above can be taken, and short circuits between taps can be prevented.

As described above, according to the present invention, there is no need to force the vacuum switch to be continuously energized, there is no risk of short circuit between taps due to vacuum leakage or contact breakage, and there is no risk of dielectric breakdown between the open contacts of the vacuum switch due to abnormal voltage. Therefore, it is possible to provide a switching switch that utilizes only the high breaking ability and long life of a vacuum switch.

Although the above explanation uses a single-resistance type as an example,
A similar configuration is also possible for a multi-resistance type with two or more resistors. For example, FIGS. 3 and 4 show examples of a two-resistance type, in which two current-limiting resistors 7a and 7b are used.
In addition, two resistor fixed contacts 6a, 6b for energization, and two resistor vacuum switches 13 are provided.
It is the same as that shown in FIG. 1 except that it is provided with resistor floating contacts 12a, 13b and two current-carrying resistance floating contacts 12a, 12b, and has the same effects.

[Brief explanation of the drawing]

Fig. 1 is a wiring diagram showing one embodiment of this invention, Fig. 2 is a sequence diagram showing the opening/closing order of each contact, Fig. 3 is a wiring diagram showing another embodiment of this invention, and Fig. 4 is FIG. 3 is a sequence diagram showing the opening/closing order of each contact. In the figure, 1 is the transformer winding, 2 is the odd number tap, 3 is the even number tap, 4 is the main fixed contact for energizing the odd number tap, 5 is the main fixed contact for energizing the even number tap,
6, 6a, 6b are resistor fixed contacts for energization,
7, 7a, 7b are current limiting resistors, 8, 10 are main floating contacts for energization, 12, 12a, 12b are resistance floating contacts for energization, 9, 11, 13, 13
Numerals a and 13b are vacuum switches, 14 is a common fixed contact for current supply, 15 is an output terminal, and 16 is a movable roller contact. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] 1 A main fixed contact for energizing the odd-numbered taps connected to the odd-numbered taps of the transformer winding, a main fixed contact for energizing the even-numbered taps connected to the even-numbered taps, and a current-limiting resistor connected in series with at least one of the above-mentioned odd-numbered taps or even-numbered taps. The main floating contact for energizing the odd taps is connected to the odd taps via the vacuum switch for the odd taps, and the main floating contact for energizing the even taps is connected to the even taps via the vacuum switch for the even taps. The main floating contact, the current-carrying resistance floating contact connected to the current-carrying resistance fixed contact via the resistance vacuum switch, the current-carrying common fixed contact connected to the output terminal, this current-carrying common fixed contact and the above contact group. The vacuum switch for odd-numbered taps closes earlier and opens later than the main fixed contact for energizing odd-numbered taps, and the vacuum switch for odd-numbered taps closes and opens earlier than the main floating contact for energizing odd-numbered taps. The even-numbered taps close earlier and open later than the main fixed contact for energization, the even-numbered taps close and open earlier than the main floating contact for energization, the vacuum switch for resistor closes earlier and opens later than the fixed energized contact, and it closes later than the floating resistor contact for energization. A vacuum switch type changeover switch that is characterized by its ability to open quickly.