JPH0349525A - Switching method for low voltage side load of power distribution transformer - Google Patents

Abstract

PURPOSE:To enable simple switching and connection by using a single changeover switch which closes contactors automatically so as to sequentially open primary cutouts connected to the high voltage side of a power distribution transformer of one bank. CONSTITUTION:When the load of bank B of banks A, B is switched, a changeover switch S is connected through bypass cables L between low voltage sides of both the banks A, B connected with primary cutouts PC to high voltage sides of transformers Tra, Trb. The switch S automatically closes contactors of the respective phases in response to a zero-volt state on the load side. Further, it sequentially opens the cutouts P connected to the high voltage side of a power distribution transformer Trb of the bank B. Thus, even in a system in which a low voltage switch is not provided at the low voltage side of the transformers Tra, Trb, this method can be employed with only one changeover switch.

Description

[Detailed Description of the Invention] [Industrial Application] The present invention is applicable to low voltage l11f't of distribution transformers such as pole transformers.
This relates to a load switching method.

[Background Art] With the development of an advanced information society, the demand for a stable supply of electric power is increasing. In addition, construction power outages are becoming more difficult year by year, and methods to carry out construction work without causing power outages to customers have been proposed and implemented. For example, when replacing the pole transformer 'T'rb of bank B, one of the two banks A and B, the load LF3 of bank B is switched to bank A, and the load LF3 of bank B is switched to bank A while the work of bank B is being carried out. The load LB is supplied with power. Conventionally, as a method for switching the load L B of the B bank to the A bank, as shown in Fig. 3, for the low voltage switching 8LS connected to the low voltage side of the 8 banks, when the load side becomes no voltage, a corresponding switch is applied. Automatic opening/closing (10 msa)
After connecting the switching switch 31 that closes the bank (within c) in parallel, and connecting the switching switch S2 of Naranari similar to the above to the branch point of both banks A and B, switching is performed according to the following operation. There is a method. ■Switch switch SL to ON state by manual operation. ■Off by low voltage switch LS'& manual operation
' Put it in F state. ■Turn the switching switch S1 to the OFF state by manual operation. ■ Off-i switch S2 is load L }3
It detects that fermentation 1 has become voltageless, and instantaneously
(within ec), the current I1 starts to flow from the eight banks to the load L B ffFJ.

[Problem to be solved by the invention] However, in the above-mentioned method, a low voltage switch (low voltage branch box) is required for the secondary ■ (low voltage measurement) of the transformer, so a low voltage switch is installed on the low voltage side of the transformer. There is a problem that this method cannot be implemented in systems that do not have a switch (low-voltage branch box).Also, two switching switches are required, which requires extra work to connect the switching switches and remove them after construction is completed. The present invention has been made in view of the above problems, and its purpose is to measure the low voltage of a t-transformer by using a low voltage switch (
The purpose of this invention is to provide a low voltage side load switching method for a t-transformer that can be implemented even in a system without a low voltage branch box (low voltage branch box) and requires only one switching switch. Means for Solving Problem F] In order to achieve the above-mentioned object, in the present invention, when switching the load of one bank to the other bank, during the low voltage control of both banks, the load n is switched to the natural voltage. In response to this, a switching switch is connected that automatically closes the switching section of each phase, and the primary cutout connected to the high voltage side of the distribution transformer of one bank is opened in sequence. did. [n: for] In the present invention, the high voltage of the ghost transformer of one bank that performs the switching of one load}1! When the primary cutouts connected to II are opened in sequence, the opening/closing part of each phase of the cutout switch connected between the low voltage sides of both banks will be connected to the phase where the primary power cutout is opened, and from the corresponding phase. Automatically closes to In and the load is switched.

[Examples] Examples that embody the present invention will be described below with reference to the drawings.

A. When switching the 11 loads of one n bank of both banks B, the transformers 'I'ra and 'T' are connected as shown in Figure 2.
A switching switch S is connected using a bypass cable 1 between the low voltage terminals of banks A and B, each of which has a primary cutout PC connected to the high voltage side of rb. As shown in FIG. 2, the switching switch S is connected to the electric three-phase wiring U.
V. Sanwa's switching units su, sv, and s1 are provided corresponding to W, and when the load of the corresponding phase is measured or there is no voltage, a detector (not shown) detects this and instantly switches the switching units su, sv, and su. (within 10 rBsec). Next, the switching switch S is connected to the switching section su of each phase,
sv, SIll are opened, the primary cutout pcu. pcv. PC
Manually open the gates one by one. First, cutout P
When C IJ is opened, there is no voltage between the load side terminals of the switching parts SIJ and SV, and the switching switch S detects this and automatically closes the switching parts su and sv within 1 Olsec. At this stage, if there is a three-phase load as shown in Figure 2,
-■ Voltage is supplied from the transformer "I'ra," and V-W voltage is supplied from the transformer Trb.Next, the power is supplied from the transformer "I'ra."
When V is opened, there is no pressure between the load terminals of the switching section Sv, and the switching section Sv automatically closes within 10 nsec in the same way as above, and the switching sections su and s of each phase of the switching switch S are closed automatically within 10 nsec.
v and s are all in the ON state, and current 11 flows from the A bank to the load of the B bank through the switching switch 8S. Finally, the cutout PCW is opened to complete the load switching operation. After the switching switch S detects no voltage on the same load, the switching unit su. The time until sv,s- closes is 1
Since the time is less than 0 nsec, the operator can close the opening/closing part su. s
v. Each cutout p is closed without acknowledging that the sw is closed.
Even if the fins of cu, PCV, and PCw are opened, the load switching operation is completed smoothly. In addition, cutout PCt
The order of opening of l, PCV, and PCW is not limited to the order of nii, but may be performed in the order of }) C W-, P C V-, and P Cυ. If opened in this order, cutout }) CO , PCV . PCW and each opening/closing part su, s
v, s- operation +1r! The sequence is as follows. PC prisoner release-SV, SW ON→PCv release-SUON=PC
[Effect of the invention by opening U] As detailed above, according to the present invention, even in a system where the low voltage switch of the distribution transformer does not have a low voltage switch (low voltage branch box), the negative tzz of one bank can be transferred to the other bank. Switching can be done instantly, making it possible to extremely shorten power outages during transformer replacement work. In addition, since only one switching switch is required for the switching work, the effort required to connect the switching switch and to remove it after construction is completed is reduced.

[Brief explanation of drawings]

1.2 UA shows an embodiment embodying the present invention, and Fig. 1 is a schematic diagram of a state in which a switching switch is connected between both banks, and Fig. 2 is a wiring diagram showing all three phases. FIG. 3 is a schematic diagram showing a conventional method. 7” Primary Cutout PC.})CO, PCV
, PCw, transformation 3 T' ra, 'I' rb, switching opening/closing 8S, opening/closing parts s++, sv, s-.

Claims (1)

[Claims] 1. When switching the load of one bank to the other bank,
A switching switch is connected between the low voltage sides of both banks to automatically close the switching parts of each phase when there is no voltage on the load side, and connected to the high voltage side of the distribution transformer of one bank. A low-voltage side load switching method for a distribution transformer, characterized by sequentially opening primary cutouts.