JPS6281929A - Resistance type on-load tap changer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a resistive on-load tap changer that switches the taps of a transformer at a load of 11A, and particularly relates to a protective bag that protects equipment from abnormal current caused by short circuits between taps. Regarding.

[Technical background of the invention and its problems]

To adjust the voltage of a transformer, there is a resistive on-load tap changer (hereinafter referred to as LTC) that switches the tap winding of the transformer under load. A circuit diagram of this Lrc (71:i) is shown in FIG.
A series circuit of a current limiting resistor 6 and a resistive contact 10 and a series circuit of a current limiting resistor 7 and a resistive contact 11 are connected to the tap selection contacts 4 and 5, respectively. They are commonly connected to the output terminal 12. Furthermore, the current limiting resistor 6.7 and the resistive contact 10. Main contacts 8 and 9 for energizing loads' and [1ε are connected in parallel to the series circuit consisting of II. FIG. 4 shows such an LTC switching operation sequence. For example, in order to switch from the even tap 2 to the odd tap 3, the main contact 8 is first opened at time t, the load current is commutated to the resistance contact 1, and the current is suppressed to a low value by the current limiting resistor 6. Then at time t2
, the resistance contact 11 closes, and as a result, the current limiting resistors 6, 7 and the resistance contact 10 are connected between the even number tap 2 and the odd number tap 3. I
A bridge condition is formed through I, through which load current and circulating current flow. Next, at time 3, the resistance contact 10 opens and the load current moves to the resistance contact 11 side. Next, at time t4, the main contactor 9 is turned on, and the load current is completely transferred to the main contactor 9, completing tap switching.

However, in LTCs that perform such operations, mechanical troubles, main contacts 8 and 9, and resistance contacts 1 may occur.
If the switching ability decreases by 0.11, the arc that occurs when the current is cut off will be prolonged, and there is a risk that the even-numbered taps 2 and the odd-numbered taps 3 will be short-circuited.

If such a state occurs, an extremely large short circuit current will flow, and there is a risk that not only the LTC but also the main body of the transformer to which the LTC is attached will be seriously damaged.

[Purpose of the invention]

In view of the above points, the present invention has been developed to prevent mechanical troubles and normal
If an abnormal condition occurs where the contact cannot open or close and leads to a short circuit at pole lfJ, it should be detected immediately and the L
It is an object of the present invention to provide an on-load tap changer equipped with a protection device capable of preventing damage to a TC or a transformer main body.

[Summary of the invention]

In order to achieve the above objects, the present invention includes a light emitting element that emits light according to a voltage applied to a current limiting resistor, and a light emitting element that receives light from the light emitting element in opposition to the light emitting element. An eye bar is provided so that when a current flows through the current limiting resistor for more than a predetermined time due to a prolonged arc, the light from the light emitting element is blocked by gas generated, and an abnormal state is detected by a determination unit connected to an optical fiber. It is characterized by what it did.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In FIG. 1, parts that are the same as those of the prior art are given the same reference numerals. The electrical circuit connection of the TC is exactly the same as the conventional one, so its explanation will be omitted. In the present invention, voltage detectors 13 and 14 connected in parallel to both ends of R2 of current limiting resistors 6 and 7 composed of R1 and 12 are provided, and a light emitting element such as a light emitting diode that emits light by a voltage proportional to the applied voltage is provided. Connect 15.16. In addition, as shown in Figure 2, above the current limiting resistors 6 and 7, there is a tube with a flared bottom end to collect and guide the gas generated when current flows through the current limiting resistors 6 and 7 for a predetermined period of time or more and heats up. 17 are provided. In the middle of the tube 17, the light emitting elements 15 and 16 are installed at opposite positions, and one end of an optical fiber 18 is attached so that the light from the light emitting elements 15 and 16 can be received through the tube 17.

Further, the other end of the optical fiber 18 is guided to a determining section 19.

Next, the operation of the present invention will be explained. The LTC tap switching operation is performed according to the operation sequence shown in FIG. 4, as described above. In normal switching operation, no current flows through the current limiting resistors 6 and 7 for a predetermined period of time or longer, and no gas is generated because they are not heated. In this state, light from the light emitting elements 15 and 16 attached to the tube 17 is normally transmitted to the optical fiber 18. However, mechanical troubles and resistance contact 10.
If an arc occurs for a longer time than expected due to a decrease in the switching ability of the current limiting resistors 6 and 7, the current limiting resistors 6 and 7 are heated to a predetermined temperature or higher, and gas is generated from the current limiting resistors 6 and 7.

This gas is collected by tube 17 and directed upwards to interrupt the light that was being transmitted from light emitting elements 15, 16 to optical fiber 18. The judgment part 1 indicates that this light has been cut off.
9, the circuit breaker is immediately tripped or an alarm is generated to prevent damage to the LTC or transformer body due to short circuit current.

〔Effect of the invention〕

As described above, according to the present invention, a light emitting element that emits light in response to a voltage applied to a current limiting resistor, and an optical fiber facing the light emitting element that receives light from the light emitting element are provided, and the length of the arc causes a predetermined amount of light to be applied to the current limiting resistor. Since the gas generated when current flows for more than a certain period of time cuts off the light from the light emitting element and detects abnormal conditions, 1) mechanical troubles or normal opening/closing operations of the contacts may not be achieved. Even if an abnormal condition occurs that leads to a short circuit between poles, it can be detected immediately and the LTC
Accordingly, it is possible to obtain an on-load tap changer equipped with a protection device that can prevent damage to the main body of the transformer.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, Fig. 2 is an enlarged perspective view showing the main parts, Fig. 3 is a circuit diagram showing a conventional on-load tap changer, and Fig. 4 is a circuit diagram showing an on-load tap changer. It is an operation sequence diagram of a tap changer. 1・Tap winding, 2,3・・Tap 6.7・
...Current limiting resistor, 8,9...Main contact 10, II
...Resistance contactor, 13.14...Voltage detector 15, 1
6... Light emitting element, 17... Tube 18... Optical fiber, 19... Judgment section. Agent Patent Attorney Noriyuki Chika Yudo Hirofumi Futamata Figure 1 Figure 2

Claims (1)

[Claims] Voltage applied to the current-limiting resistor in a resistive load tap changer having a series circuit of a main contact for applying load current, a current-limiting resistor connected in parallel with the main contact, and a resistance contact. A light emitting element that emits light by a light emitting element and an optical fiber that receives light from the light emitting element are provided, and when a current flows through the current limiting resistor for a predetermined period or longer, the light from the light emitting element is cut off by gas generated to prevent an abnormal state. A resistive load tap changer characterized by detecting the load.