JP2687821B2 - Tap switching device under load - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-load tap switching device using a cam switch.

[0002]

2. Description of the Related Art FIG. 3 shows an example of a load tap changer using a conventional cam switch. The lead wires 7 of the plurality of taps of the transformer winding 1 are connected to the input sides of the main circuit contacts 4 of the cam switch 6, and the lead wires 8 connected in parallel to the lead wire 7 are switched by the cam switch 6. Connect to the input side of the contact for use 5. The lead wire 8 extending from the output side of the switching contact 5 is connected to each current limiting resistor 2, and the output side of the current limiting resistor 2 and the lead wire 7 extending from the output side of the main circuit contact 4 are connected. Are collectively connected, and the collectively connected terminal and one end of the transformer winding 1 become the output terminal 3. Main circuit contact 4 and switching contact 5 of each cam switch 6
Corresponding to the rotation of the shaft of the cam switch 6, the opening / closing operation is performed according to the timing chart shown in FIG. In FIG. 4, the numbers I to IV on the horizontal axis indicate the notch positions of the cam switch 6, and the numbers on the vertical axis indicate the contact numbers, which correspond to FIG. Regarding the open / closed state of the contact, it is closed when it is in a black-painted state in FIG. 4, and is open in other cases. That is, when the notch position of the cam switch 6 is moved from the direction I to the direction IV, the main circuit contact 4 and the switching contact 5 of the contact numbers 1 to 4 open and close as shown in FIG.

[0003]

In order to perform the tap switching operation under load, it is necessary to continuously open and close the contacts so that the output does not become a no-voltage. As an example, looking at the circuit operation of FIG. 3 when switching from tap I to II from the timing chart of FIG. 4, there is a time during which the contact number and the switching contact 5 are both closed. . At this time, the closed loop 9 becomes a short circuit for one tap, but the current flowing in the closed loop 9 is limited by the current limiting resistor 2 for circuit protection. As described above, in the conventional circuit configuration, at least one every current limiting resistor 2 is required for tap switching at the time of load, and when the number of taps increases, the number of current limiting resistors 2 and the current limiting resistor 2 increase. Resistance 2
The number of switching contacts 5 connected to is also increased. for that reason,
The circuit configuration becomes complicated, the size of the tap changer as a whole becomes large, and the cost also increases due to these. In view of this, the present invention is intended to reduce the load as well as to reduce the load tap switching device using a cam switch.

[0004]

[Summary of the Invention] Lead wires of a plurality of taps of a transformer winding are connected to an input side of a main circuit contact of a cam switch, and each main circuit is connected to an output side of the main circuit contact. Connect the parallel circuit of the current limiting resistor and the switching contact to the terminals that connect the lead wires that are output from every other contact all at once, and the lead wire that is output from the parallel circuit and the rest that is not connected to the parallel circuit. Connect with the leader line of
The terminal and one end of the transformer winding are the output terminals.

[0005]

In the load tap changer as described above, only one current limiting resistor and one changeover contact are required for tap change even for a plurality of taps.

[0006]

FIG. 1 shows an example of an on-load tap switching device using a cam switch according to the present invention. The lead wires 7 of the plurality of taps of the transformer winding 1 are connected to the input side of each main circuit contact 4 of the cam switch 6. On the output side of the main circuit contacts 4 of the cam switch 6, the current limiting resistance 2 and the switching contacts 5 are connected in parallel to the terminals to which the lead wires 7 that are output from every other main circuit contact 4 are collectively connected. Connected to the circuit, the lead wire 8 from the parallel circuit and the remaining lead wire 7 not connected to the parallel circuit are collectively connected, and its terminal and one end of the transformer winding 1 are output terminals. Set to 3. 2 is a timing chart showing the opening / closing operation of each main circuit contact 4 and switching contact 5 of the cam switch 6 in FIG. In FIG. 2, the numbers on the vertical axis are
The contact numbers are shown and correspond to FIG. Also, the horizontal axis I to IV
Each number of indicates the notch position of the cam switch. The open / closed state of the contact numbers 1 to 4 indicates closed when blacked out, and open otherwise.

[0007]

As described above, according to the present invention, since only one current limiting resistor and switching contact are required for switching a plurality of taps under load, the circuit is simplified and the device is downsized. And cost reduction can be achieved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a load tap switching device using a cam switch according to the present invention.

FIG. 2 is a timing chart showing an opening and closing operation of the cam switch of FIG.

FIG. 3 is a diagram showing an example of a conventional tap switching device using a cam switch during load.

FIG. 4 is a timing chart showing an opening / closing operation of the cam switch of FIG. 3;

[Explanation of symbols]

 1 Transformer winding 2 Current limiting resistor 3 Output terminal 4 Main circuit contact 5 Switching contact 6 Cam switch 7 Lead wire 8 Lead wire 9 Closed loop

Claims (1)

(57) [Claims] 1. Lead wires of a plurality of taps of a transformer winding are connected to an input side of a main circuit contact of a cam switch, and one of the main circuit contacts is provided on the output side of the main circuit contact. Connect the circuit in which the current limiting resistance and the switching contact are connected in parallel to the terminal that collectively connects the lead wires that appear every other time.
A tap switching device under load, in which a lead wire output from the parallel circuit and the remaining lead wires not connected to the parallel circuit are collectively connected, and the terminal and one end of the transformer winding are used as output terminals.