JP3350456B2 - Detector for ultra-current-limited power fuse - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detecting device for an ultra-current-limited power fuse for protecting a high / low voltage distribution system or for backing up a circuit breaker, which cuts off an overcurrent at a very high speed when a short circuit occurs. About.

[0002]

2. Description of the Related Art As a super-current-limiting power fuse described above, a cut-off cylinder incorporating a drive capsule (special electric detonator) for opening contacts is combined with a current-limiting fuse connected in parallel to the cut-off cylinder. The ultra-current-limited fuse is known as, for example, "Ultrap Fuse" (trade name of a product of Fuji Electric Co., Ltd.), and its structure and an outline of the shut-off principle are described in, for example, "Fuji Times" Vol. Page 21 "Ultra-limit fuse using electric detonator (ultrap fuse)"
It has been introduced as.

[0003] In this super-current-limiting power fuse, the normal energization is performed at the contacts of a shut-off cylinder, and when an overcurrent such as a short-circuit current flows in the energized path, the current is detected to drive the drive capsule. Then, the explosive force of the electric detonator opens the contacts of the shut-off cylinder to divert the current to the current-limiting fuse and complete the interrupt with the current-limiting fuse. The operation principle will be described with reference to FIG. That is, the super-current-limiting power fuse includes a breaking tube 2 inserted and connected to the current path 1, a current-limiting fuse 3 connected in parallel with the breaking tube 2, a current transformer 4, and a detection unit 5. Here, the shut-off cylinder 2 has a built-in drive capsule (electric detonator) for opening the contact 2a, while the detecting unit 5 includes a resistor 5a and an SSS
An element (two-way two-terminal thyristor) 5b and an ignition transformer 5c are provided, and a drive capsule 2b of the shutoff cylinder 2 is connected to a secondary side of the ignition transformer 5c. The current limiting fuse 3 is a current limiting fuse having a smaller rated current than the rated current of the current path 1.

In such a configuration, the current of the current path 1 always flows through the contact 2a of the shutoff cylinder 2, and the current I of the current path 1 is applied to both ends of the resistor 5a of the detection unit 5 via the current transformer 4. A proportional voltage (e = iR) is generated. Here, if the current I in the current path 1 is equal to or less than the operating current value, the voltage e is lower than the breakover voltage of the SSS element 5b, and no ignition current is supplied to the drive capsule 2b. On the other hand, a short circuit accident or the like occurs in the circuit of the current path 1 and an overcurrent flows,
The voltage e across the resistor 5a, which rises in proportion to this current, becomes S
When the state exceeds the breakover voltage of the SS element 5b, a part of the current i flows to the ignition transformer 5c to ignite the drive capsule (electric detonator) 2b connected to its secondary side. As a result, the contact 2a of the cutoff cylinder 2 opens in a very short time due to the explosive force of the electric detonator, and all the overcurrent is transferred to the current limiting fuse 3, so that the arc of the contact 2a is extinguished. On the other hand, when an overcurrent is commutated to the current limiting fuse 3, the current limiting fuse 3 is blown almost instantaneously to complete the current limiting interruption.

[0005]

By the way, when the above-mentioned conventional super-current power fuse is applied to, for example, a backup of a circuit breaker of a three-phase power system, the following functions and reliability are required. Problems remain. In other words, in the conventional ultra-current-limiting power fuse, including the detection unit, each phase is independent, and each phase does not have a linking function. For this reason, when a short-circuit accident occurs, the super-current-limiting power fuses of two of the three phases may be blown out depending on the situation, and the remaining one phase may not operate. Such an operation is incomplete as a backup function of the circuit breaker. Further, as another problem, when the protection power system includes a generator, a motor, and the like, there is a possibility that a super-current-limiting power fuse may malfunction due to a starting current of the generator or the motor exceeding the rated current.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to solve the above-mentioned problem that may occur when a super-current-limiting power fuse is applied to protection of a polyphase system. An interlocking function that forcibly cuts off the super-current power fuse of the other phase when the super-current power fuse blows, and prevents the malfunction of the super-current power fuse due to the starting current of the generator, motor, etc. It is an object of the present invention to provide a novel ultra-current-limiting power fuse detection device having such an interlock function.

[0007]

In order to achieve the above-mentioned object, in the detection device of the present invention, first, as an interlock function, when an external interlock signal is received, a super-current-limiting power fuse is brought into an inoperative state. And an interlock means for holding the interlock. Also, as an interlocking function,
When at least one phase of the super-current power fuse installed in each of the three-phase current-carrying paths is cut off, an interlocking signal is supplied from the detection device of the phase that has performed the cut-off operation to the detection device of the other phase, so that the super-current power fuse is detected. Is provided with an interlocking means for forcibly interrupting the operation.

Here, as the transmission means of the interlocking signal and the interlock signal, an optical fiber, an optical signal transmitting / receiving module, and an optical signal receiving module can be used. For this purpose, the main circuit of the detection device is preferably constituted by an electronic circuit.

[0009]

In the above configuration, when the generators, motors, etc. in the system are started, an interlock signal is sent from the operation control panel to the detection device of the super limit current power fuse of each phase in synchronization with the start, While the interlock signal is given, the super-current-limiting power fuse is kept in a non-operation state so as not to malfunction due to the starting current of the generator and the motor flowing through the current path. Further, for example, in the event of a short circuit, for example, if one of the super-current limiting fuses installed in each of the three-phase circuit current-carrying paths has a cut-off operation, and the remaining two phases are inoperative, Then, an interlocking signal is given from the detecting device for the super-current power fuse of the phase that has been blown to the other two-phase detecting devices, and the super-current power fuses of these phases are forcibly operated to be blown. This greatly improves the function and reliability of the ultra-current-limiting power fuse when applied to a multiphase circuit.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. In the figure, the same parts corresponding to FIG. 3 are denoted by the same reference numerals.

FIG. 1A shows a super-current limiting power fuse 6 (FIG. 3).
Block diagram of a detection device 5 attached to one phase of a combination of the cutoff cylinder 2 and the current limiting fuse 3 in FIG.
FIG. 1B is a block circuit diagram showing an interlocking and interlocking function for linking detection devices of the super-current-limiting power fuses 6 installed in the three-phase (R, S, T) phase circuits, and FIG. FIG. 2 is a specific circuit diagram of FIG.

First, in FIG. 1A, a detecting device 5 includes a rectifier circuit 7, a power supply circuit 8, and a rectifier circuit 7 connected to the secondary side of a current transformer 5.
Current detection circuit 9, amplification circuit 10, operating current adjustment circuit 1
1, a drive circuit 12 for supplying an ignition current to a drive capsule (electric detonator) 2a, and its main circuit is constituted by an electronic circuit as shown in FIG. Further, as shown in FIG. 1B, the driving circuit 12 of the detecting device 5 transmits the interlocking signal and the inter-working signal described later through optical fiber signal transmission circuits 13 and 14 wired between the R, S, and T phases. The lock signal is input and output. In addition, 1
Reference numeral 5 denotes an electric / optical signal converter that externally supplies an interlock signal to the detection device of each phase.

Next, the circuit configuration and operation of the detection device will be described in detail with reference to FIG. In the figure, first, the rectifier circuit 7 connected to the secondary side of the current transformer 4 is constituted by a bridge of a diode 16. The power supply circuit 8 has a capacitor 17.
The capacitor 17 is charged with the DC current rectified by the rectifier circuit 7 and used as a main power supply of the detection device 5. Further, the current detection circuit 9 in FIG.
ET 18, a current detecting resistor 19, an operational amplifier 20 in the amplifier circuit 10, and a variable resistor 2 in the operating current adjusting circuit 11.
1, the resistor 22, and the Zener diode 23,
The circuit 2 includes an operational amplifier 24 and a thyristor 25 to form respective circuits. Reference numeral 26 denotes an output terminal for supplying an ignition current to the drive capsule 2b (see FIG. 3) of the shutoff cylinder 2. On the other hand, the right side circuit part of FIG.
The two optical signal transmission / reception modules 2 that transmit and receive the interlocking signal when the super-current-limiting fuse blows with another two-phase detection device through the optical signal transmission circuit 13
7 and 28 (if the detection device shown is the R phase, the modules 27 and 28 are used for signal transmission between the RS and RT phases, respectively), and are externally applied through the optical signal transmission circuit 14. And an optical signal receiving module 29 for receiving an interlock signal. Reference numeral 30 denotes a three-terminal regulator (voltage regulator) for applying a constant voltage to the modules 27 to 28, reference numeral 31 denotes a control transistor for outputting an interlocking signal from the optical signal transmitting / receiving modules 27 and 28, and the other components will be described. Is omitted.

In such a configuration, first, the operating current value of the super-current-limiting power fuse is set by the variable resistor 21, and is generated at both ends of the resistor 22 and the resistor 19 when a current corresponding to the operating current value flows through the conduction path 1. Adjust so that the voltages are equal. Further, the secondary current of the current transformer 4 is rectified to DC by the rectifier circuit 7 and charges the capacitor 17 of the power supply circuit 8. In this case, if the + input terminal voltage of the operational amplifier 20 becomes higher than the reference voltage of the Zener diode 23, the operational amplifier 20 operates, the MOSFET 18 is turned on, and the current is reduced by the resistance 1
9, the capacitor 17 of the power supply circuit 8 is discharged.
That is, the charging of the power supply capacitor 17 and the energization of the resistor 19 are alternately repeated for each cycle of the current (AC) flowing through the energizing path 1 to secure the main power supply of the detecting device 5, and 1 is detected.

In this state, an overcurrent flows through the current path 1 due to a short circuit accident in the power system, and as a result, the current detection circuit 9
When the voltage generated in the resistor 19 becomes larger than the voltage generated in the resistor 22, the operational amplifier 24 of the drive circuit 12 which operates these voltages as + and − input voltages operates,
As a result, the thyristor 25 breaks over and the drive capsule (electric detonator) 2 of the shutoff cylinder 2 is output from the output terminal 26.
a (see FIG. 3). As a result, FIG.
As described above, the contact of the breaking cylinder 2 of the ultra-current-limiting power fuse performs the opening operation, and accordingly, an overcurrent is diverted to the current-limiting fuse 3 to perform the current limiting interruption.

On the other hand, when the thyristor 25 breaks over and the ultra-current-limiting power fuse blows, the transistor 31 described above is turned on at the same time, whereby the optical signal transmitting / receiving modules 27 and 28 transmit the other two-phase detectors 5. And simultaneously transmit the interlocking signal in parallel.

Here, when the optical signal transmitting / receiving modules 27 to 28 in the other-phase detecting device 5 receive the interlocking signal, the signal voltage is applied to the + of the operational amplifier 24 of the driving circuit 12.
The operational amplifier 24 is operated in addition to the input terminal. As a result, the thyristor 25 breaks over and gives an ignition current to the drive capsule 2a of the shut-off cylinder 2, so that the super-current power fuse that was inactive at the time of the occurrence of the short-circuit accident is linked to the super-current power fuse that has operated to shut off. To forcibly shut off. In other words, among the super-current limiting fuses installed in each of the R, S, and T phases, at least one of the super-limiting power fuses generates a cutoff operation command (ignition signal to the drive capsule (electric detonator)). And 2 which remains in conjunction with this
A shutoff command is given to the three-phase super-current power fuses in parallel, and the three-phase super-current power fuses are forcibly shut off almost simultaneously.

Next, the interlock function of the detection device will be described. That is, when the generator, electric motor, and the like in the protection system are started, the detection device 5 of the super-current-limiting power fuse 6 installed in each of the R, S, and T phases as shown in FIG. When the interlock signal is supplied to the optical signal receiving module 29 through the electrical / optical signal converter 15 and the optical signal transmission circuit 14, the detection device 5 that has received the interlock signal converts the signal voltage to the operational amplifier 24 of the drive circuit 12. -Apply to the input terminal. By the way, this reception signal voltage is previously determined to be higher than the voltage generated in the resistor 22 of the current adjustment circuit. Therefore, even if a starting current larger than the rated current flows through the current path 1 in this state, the operational amplifier 24 does not work. That is, the generator,
By applying an interlock signal to the super-current power fuse of each phase from the outside at the time of starting the motor, etc., the super-current power fuse is held in an inoperative state while the interlock signal is applied. Therefore, there is no possibility that the super-current power fuse malfunctions due to the starting current. This interlock function is effective even when a super-current-limiting power fuse is applied to a single-phase circuit.

[0019]

As described above, in the detection device for a super-current power fuse of the present invention, the interlocking function is provided between the super-current power fuses installed in the respective phases, for example, three times. When a super-current power fuse for at least one phase is blown out by a short-circuit accident, etc. for a super-current power fuse applied to a three-phase power system, the other two-phase super current power The fuses can be forcibly cut off almost simultaneously, and this is extremely effective particularly when a super-current-limiting fuse is used as a backup for a circuit breaker. In addition, an interlock function is provided to the detecting device of the ultra-current-limiting power fuse, and an interlock signal is externally applied at the same time as the generator and the motor in the system are started, so that the ultra-current-limiting power fuse is disabled. It can be maintained in the operating state, whereby the malfunction of the ultra-current-limiting power fuse caused by the starting current of the generator, the electric motor or the like can be avoided beforehand, and the reliability can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a detection device for a super-current-limiting power fuse according to an embodiment of the present invention, in which (a) is a block circuit diagram of a detection device for one phase, and (b) is detected between three phases. Block circuit diagram showing the interlock circuit and interlock circuit that link the devices

FIG. 2 is a circuit diagram of a specific embodiment of FIG.

FIG. 3 is a configuration circuit diagram of a conventional ultra-current-limiting power fuse and its detection unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Current-carrying path 2 Cut-off cylinder 2a Contact 2b Drive capsule 3 Current-limiting fuse 4 Current transformer 5 Detector 6 Super-current-limiting power fuse 13 Interlocking signal transmission circuit 14 Interlock signal transmission circuit 27 Optical signal transmission / reception module 28 Optical signal transmission / reception module 29 Optical signal receiving module

──────────────────────────────────────────────────続 き Continuing on the front page (72) Kazunori Kobayashi 1-1-1, Tanabe Nitta, Kawasaki-ku, Kawasaki, Kanagawa Prefecture Inside Fuji Electric Co., Ltd. No. 1 Fuji Electric Co., Ltd. (56) References JP-A-48-67766 (JP, A) JP-A-4-54900 (JP, A) JP-A-57-210536 (JP, A) JP-A-60-1985 86727 (JP, A) JP-A-60-79635 (JP, A) JP-B-49-7418 (JP, B1) JP-B-45-28139 (JP, B1) (58) Fields investigated (Int. ⁷ , DB name) H01H 85/46

Claims (2)

(57) [Claims] 1. A detecting device attached to an ultra-current-limiting power fuse, which is a combination of a breaking cylinder containing a driving capsule for opening a contact and a current limiting fuse connected in parallel to the breaking cylinder. A current flowing through the current path of the protection system through the flower is detected, and when the current exceeds a preset operating current value, the drive capsule of the shut-off cylinder is operated. A detection device for a super limit current power fuse, comprising interlock means for holding the super limit current power fuse in an inoperative state when received. 2. A detecting device attached to a super-current-limiting power fuse, which is a combination of a breaking cylinder containing a drive capsule for opening a contact and a current limiting fuse connected in parallel to the breaking cylinder. A current flowing through the current path of the protection system through the flower is detected, and when the current exceeds a preset operating current value, the drive capsule of the shut-off cylinder is operated. The interlock means for holding the super-current power fuse in a non-operational state when received, and when at least one phase of the super-current power fuse installed in each of the three-phase conduction paths has been blown, the blow operation has been performed. Interlocking means for simultaneously providing an interlocking signal from the phase detection device to another two-phase detection device in parallel and forcibly shutting off the three-phase super-current power fuse substantially simultaneously. Detection device for current limiting power fuse.