JPS5937768B2 - temperature monitoring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a temperature sensor provided in a transformer winding, an external power supply for feeding power to the temperature sensor, a relay connected to the temperature sensor and provided outside the transformer winding, and a temperature sensor provided in the transformer winding. The present invention relates to a device for monitoring the temperature of a transformer winding, the device having a display device connected to the transformer and arranged at a distance from the transformer.

For temperature monitoring of dry type transformer windings, especially low voltage windings,
A temperature sensor is wound together within the winding to be monitored.

When a predetermined response temperature occurs, this temperature sensor provides a signal via a trip device, for example by actuation of a relay, with which further switch operations are initiated. The temperature sensor is electrically isolated and provided in the winding.

However, the insulation commonly used in this case is approximately 250
It is only sufficient for test voltages up to 0V. If the test voltage, or even the operating voltage, is higher, the device can no longer be used because its insulation is relatively weak. However, increasing the insulation creates new voltage problems due to the resulting non-uniformity of the electric field, as well as making accurate temperature sensing difficult. A device with a temperature sensor is known from German Patent No. 1928738.

This known device is used for overload protection of high-voltage equipment. The electrical insulation of this temperature sensor is provided by a ceramic material with good thermal conductivity. However, this solution requires that the lead-out leads be insulated in the usual way, which can lead to failure in the event of surge voltages, and also account for partial discharges. Has its drawbacks. Therefore, an object of the present invention is to monitor the winding temperature of a transformer with a rated voltage of 1150 V (>R1N) or more, especially a dry transformer, without impairing the uniformity of the electric field within the monitored winding, and An object of the present invention is to provide a device that can be installed without causing partial discharge.

According to the present invention, this purpose is to provide a temperature sensor provided in the transformer winding, an external power supply for powering the temperature sensor, a relay connected to the temperature sensor and located outside the transformer winding, and a relay located outside the transformer winding. In a device for monitoring the temperature of a transformer winding, the temperature sensor and the relay are electrically separated from the external power supply for power supply and the display device, and the display device is connected to an isolation transformer. The isolation transformer has two windings on each of the outer legs of the three core legs, and the middle core leg acts as a return leg depending on the circuit condition, and the isolation transformer has two windings on each outer core leg. One core leg with wires is provided with an input winding that receives power from the power supply and a power supply winding for the relay, and the other core leg with wires is equipped with
As a secondary winding, it is short-circuited by the relay during steady operation, and is electrically parallel to the relay's power supply winding when the relay is operating.
Magnetically, an excitation winding and a trip winding for supplying power to the display device are provided, which are connected in series, and power is supplied to the relay and signal transmission to the display device is performed via an isolation transformer. This is achieved by

It is advantageous if the windings on the same core leg of the isolation transformer are arranged radially overlapping.

In an advantageous embodiment of the invention, the temperature sensors are arranged in the winding close to the star connection point of the monitored transformer winding, and all temperature sensors of the transformer each cooperate with a single relay. However, all temperature sensors are connected in series in one current circuit.

According to another advantageous embodiment of the invention, the relay has at least two contacts, one of which is closed and one of which is opened depending on the respective circuit state, and the measured value provided by the temperature sensor is connected to the relay. via an amplifier arranged upstream of the circuit, in which case the relay and the amplifier are housed in the same container as a trip device.

The device according to the invention is very advantageous in the following respects.

This means that it is still possible to use temperature sensors with only conventional insulation, which are free from the risk of causing partial discharges and which can be connected directly in series, especially when placed in the vicinity of a predetermined star connection point. Yes, in this case there is no risk of the temperature sensor compromising the safety of the entire device. The present invention will be explained in detail below with reference to illustrated embodiments.

FIG. 1 is a circuit diagram of a device according to the present invention, and FIG. 2 is a diagram showing the basic configuration of an isolation transformer. In both figures, the same parts are given the same reference numerals.

Isolation transformer 8 with a core 9 consisting of three core legs 10
is equipped with four windings 1a, Ib, ■a, and ■b.

Windings 1a, Ib are connected to terminals 1, 2, 6 and 7 and are arranged on one outer core leg 10.

The windings ■a and ■b are connected to the terminals 3, 4, 5, and 6, and are arranged concentrically next to each other on the other outer core leg 10. The central core leg 10 is not provided with a winding and simply functions as a return leg depending on the state of the circuit. Winding 1a
is connected to the power supply through its terminals 1 and 2 and acts as a power feeding input winding, inducing a voltage in the winding 1b, and this winding 1
b acts as a power supply winding for the amplifier 11 and the relay 12 downstream thereof.

In this case, the measured value to be amplified is supplied by the temperature sensor 15. The relay 12 downstream of the amplifier 11 has two relay contacts 13 and 14 forming an on/off switch, these contacts acting as closing and opening elements. Relay contacts 13 and 14 are windings 1b and ■b
According to the situation, the winding 1b is short-circuited or connected in parallel to the winding 1b. Winding ■
a can be connected to a display device (not shown) via its terminals 3 and 4. In this case, the display device is activated as required, for example optically, acoustically and/or by actuation of a switch. In steady state, that is, as long as the temperature sensor 15 is operating below a predetermined temperature, the amplifier 11
The relay 12 is maintained in a state where the relay contact 14 is closed and the relay contact 13 is open. Therefore, in this circuit state, winding b is short-circuited and no voltage is induced in winding a, and as a result no voltage is applied to the above-mentioned display device.

In this case, the magnetic flux generated by the power feeding input winding 1a passes through a closed magnetic path via the unwinding central core leg of the core 9.
If the temperature of the component being monitored now increases, the measured value given by the temperature sensor 15 changes and at a certain predetermined value a control pulse is supplied to the relay 12 via the amplifier 11.

This causes the relay 12 to operate. That is, relay contact 13
, 14 transition to the state shown in FIG. Via the relay contact 13, winding b is now parallel to winding [b, which induces a voltage in winding a to operate a display device, not shown. At this time, the winding 1a in the isolation transformer 8,
Depending on the connection and arrangement of Ib, a and b,
The magnetic flux passes through a closed magnetic path via both outer core legs of the core 9. The display device indicates the temperature rise within the winding to be monitored by emitting acoustic and/or optical signals. The display device can also operate a switch, thereby disconnecting the transformer winding being monitored. In order to eliminate the potential difference between the windings Ib, b connected to the amplifier 11 and the relay 12 and the measurement circuit,
A connection lead 17 is provided. Since the windings 1b, b are electrically separated from the windings 1a, a, the temperature sensor 1
The voltage plane of the measuring circuit including 5 can be placed above or below the voltage plane of the power supply network and the display device by an arbitrary amount.

This is because the insulation between the individual windings inside the isolation transformer 8 can be of virtually any strength.

[Brief explanation of drawings]

FIG. 1 is a connection diagram of a device according to the present invention, and FIG. 2 is a schematic configuration diagram of an isolation transformer. 1 to 7...Terminal, 8...Isolation transformer,
9... Iron core, 10... Iron core legs, 12.
...Relay, 15...Temperature sensor, 1a
...Input winding for power feeding, Ib...Feeding winding for relay, a...Secondary winding (excitation winding), b...・Secondary winding (trip winding).

Claims (1)

[Scope of Claims] 1. A temperature sensor provided in the transformer winding, an external power supply for power supplying the temperature sensor, a relay connected to the temperature sensor and located outside the transformer winding, and a temperature sensor disposed away from the transformer. In a device for monitoring the temperature of a transformer winding, the temperature sensor and the relay are electrically separated from the external power supply and the display device, and the temperature sensor and the relay are connected to the display device through an isolation transformer. Operationally coupled, the isolation transformer has two windings on each of the outer legs of the three core legs, and the middle core leg acts as a return leg depending on the circuit condition and carries the windings of the isolation transformer. One of the core legs is equipped with an input winding that receives power from the power supply and a power supply winding for the relay, and the other core leg with windings is equipped with a steady-state winding as a secondary winding. An excitation winding and a trip winding for supplying power to the display device are provided, which are short-circuited by the relay during operation, and connected electrically in parallel and magnetically in series with the power supply winding of the relay when the relay is in operation. A temperature monitoring device characterized in that power is supplied to a relay and signals are transmitted to a display device via an isolation transformer. 2. Device according to claim 1, characterized in that the relay has at least two contacts, one of which is closed and the other is open in each circuit state. 3. The measured value provided by the temperature sensor is conducted via an amplifier upstream of the relay, the relay and the amplifier being housed in the same container as a trip device. The device according to item 1 or 2.