JPS6325485B2 - - 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.

In order to put a switching switch using a vacuum switch into practical use, it is necessary to satisfy at least the following three conditions.

(i) In the unlikely event that a vacuum switch develops a vacuum leak and becomes unable to shut off, the transformer circuit breaker should be tripped quickly to prevent damage to the tap winding.

(ii) Since the vacuum switch contacts are made of an arc-resistant alloy with high contact resistance, their continuous current carrying capacity is small, so a bypass contact for current carrying must be provided in parallel.

(iii) Bypass contacts are mechanically reliable;
It should have at least a longer lifespan than the vacuum switch itself.

The present invention provides a highly practical vacuum switch type changeover switch that satisfies the above three conditions.

FIG. 1 shows an embodiment of a one-resistance switching switch according to the present invention. In the figure, 1 is a tap winding of a transformer, 2 is an odd-numbered tap provided thereon, and 3 is an even-numbered tap. 4 is the main fixed contact for energizing the odd-numbered taps, which is connected to the odd-numbered tap 2 through the contact of the tap selector (not shown), and 5 is the main fixed contact for energizing the odd-numbered tap 3, which is connected to the even-numbered tap 3 through the contact of the tap selector (not shown). The even-numbered taps are connected to the main fixed contact for energization, and the numeral 6 is a resistive fixed contact for energization that is connected to the odd-numbered taps 2 via the current limiting resistor 7. 8
10 is the main fixed contact 4 for energizing the odd-numbered taps, the main fixed contact 5 for energizing the even-numbered taps, which is connected to the output terminal 9;
and a movable roller contact that connects the energizing resistor fixed contact 6 and the energizing common fixed contact 8. 11 is a vacuum switch for odd-numbered taps connected by a lead wire 12 between the main fixed contact 4 for energizing odd-numbered taps and the common fixed contact 8 for energizing, and 13 is the main fixed contact 5 for energizing even-numbered taps and the common fixed contact for energizing. 8, a vacuum switch for even number taps is connected with a lead wire 14, and 15 is a vacuum switch for resistance, which is connected with a lead wire 16 between the energizing low resistance fixed contact 6 and the energizing common fixed contact 8. It is.

In such a device, in order to switch from odd-numbered taps to even-numbered taps, the movable roller contact 1
0 from the position indicated by the solid line on the left to the position indicated by the broken line on the right in FIG.
All you have to do is open and close it. The opening and closing sequence is shown in FIG. As you can see, the vacuum switch 11,
Since the contacts 15 and 13 are always opened later than the fixed contacts 4, 6 and 5 in the switching direction, no arc is generated between the fixed contacts 4, 6 and 5 and the movable roller contact 10. Arcing occurs only within the vacuum switches 11, 15, 13. In the odd tap position, the vacuum switch 11 is closed, but it is bypassed by the movable roller contact 10, so that most of the current flows through the movable roller contact 10.
At this time, vacuum switches 15 and 13 are open.
In the even tap position, vacuum switch 13 is closed, but this is bypassed by movable roller contact 10, so the result is similar to that described above, and vacuum switches 11, 15 are now open. If a vacuum leak occurs in the vacuum switch and the current cannot be shut off, the current will continue to flow through the vacuum switch and the connecting lead wires 12, 14 or 16 will be rated for short time. Therefore, it will melt within 1 second, for example.
As a result, an arc is generated which gasifies the surrounding insulating oil, which causes a sudden rise in pressure within the transfer switch chamber, activating a protective relay such as an instantaneous pressure relay, which activates the mains by means of its contacts. It can trip the circuit breaker and suddenly stop the transformer operation to protect it from burnout.

Even if the lead wire is thin and easily blown out, it will not be blown out because it is bypassed by the movable roller contact during normal switching.

The fixed contacts 4, 6, and 5 have a common contact surface, and although their ends are insulated from each other with a gap, they overlap with each other when making contact with the movable roller contact 10, so the movable roller contact The rolling of No. 10 is smooth, and there is no arcing due to chattering,
Less likely to cause abnormal wear due to vibration or impact. Therefore, the problems of continuous energization, vacuum leak protection, and bypass switch life are all solved, and a highly practical vacuum switch type changeover switch can be provided.

Although the above description has been made using a one-resistance type switching switch as an example, a two-resistance type or a multi-resistance type switch with more than one resistance type can also be realized.

Figures 3 and 4 show examples of two-resistance type.
In addition to providing two current limiting resistors 7a and 7b,
It is the same as the one shown in FIG. 1 except that it is provided with two energizing resistor fixed contacts 6a, 6b and two resistor vacuum switches 15a, 15b, and has the same effects.

[Brief explanation of drawings]

Fig. 1 is a wiring diagram showing one embodiment of this invention, Fig. 2 is a sequence diagram showing the opening/closing order associated with switching the contacts, Fig. 3 is a wiring diagram showing another embodiment of this invention, and Fig. 4. is a sequence diagram showing the opening/closing order accompanying switching of the contacts. 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 is a common fixed contact for energization, 9 is an output terminal, 10 is a movable roller contact, 11, 13, 15, 15a, 15b
is vacuum switch, 12, 14, 16, 16a, 1
6b is a lead wire. 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 in series with at least one of the odd-numbered taps or the even-numbered taps. The current-carrying resistor fixed contact connected to the energizing resistor fixed contact, the energizing common fixed contact connected to the common terminal, the above-mentioned odd-numbered taps energizing main fixed contact, the even-numbered taps energizing main fixed contact, the energizing resistor fixed contact and the above-mentioned energizing common fixed contact. A vacuum switch for odd-numbered taps is installed between the main fixed contact for energizing odd-numbered taps and a common fixed contact for energizing, and a vacuum switch for odd-numbered taps is installed between the main fixed contact for energizing even-numbered taps and the common fixed contact for energizing even-numbered taps. A vacuum switch for even taps is connected between the fixed contact, and a vacuum switch for resistance is connected between the energizing resistor fixed contact and the energizing common fixed contact with lead wires that have short-time energizing ability. , a vacuum switch type changeover switch characterized by closing earlier and opening later than the corresponding current-carrying fixed contacts.