JPS6035888B2 - Stationary trip device for circuit breakers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a static trip device for circuit play forces.

Conventionally, as trip devices for circuit play force, particularly molded case circuit play force (hereinafter referred to as NFB), trip devices have been used that are thermal type for long time operation and electromagnetic type for instantaneous operation.

An example of the characteristics of an NFB tripping device having such a configuration is shown in FIG. In this figure, characteristic A indicates long-time operation of the thermal type, and characteristic B indicates instantaneous operation of the electromagnetic type. Here T
indicates the operating time of NFB, and 1 indicates the current of NFB. In other words, when an overcurrent that is slightly larger than the rated current flows through the NFB, the tripping device performs a tripping operation after a predetermined time has elapsed by a long time operation as shown in characteristic A, and the NFB
trip. If an excessive current several times the rated current or more flows through the NFB, a tripping operation is immediately performed by instantaneous operation as shown in characteristic B, and the NFB is tripped. However, conventional tripping devices have the disadvantage that the adjustable range is narrow and that they must be designed and manufactured for each rated current of the NFB used.

The present invention has been made in view of the above-mentioned points, and provides a highly reliable static trip device that has a wide adjustable range and is applicable to NFBs having various rated currents. The purpose is to

In order to achieve this objective, the present invention connects a haze current setting circuit and a time delay circuit in series, and
The next output current is directly passed through the haze current setting circuit and the time delay circuit in series, thereby simplifying and correcting the adjustment and improving reliability.

That is, in this invention, an alternating current load current is detected by a current transformer, and depending on the magnitude of this detected value, a static type of circuit play force is generated which generates an inverse time limit or an instantaneous tripping signal to the circuit play force. In the trip device, after the load current is detected by the first current transformer 4, the rectifier 5
A second current transformer 17 is connected in series with a first load current detection circuit that rectifies the current and extracts it as a direct current, and the rectifier 5 connected to the secondary side of the first current transformer 4. A second load current detection circuit is connected to the output side of the second load current detection circuit, which rectifies the output of the current transformer 17 and extracts the load current as a direct current; a current setting circuit having a switching element 23 that is activated when the current level exceeds 100%; and a current setting circuit that is connected to the output side of the first load current detection circuit and detects the first load current based on the on/off operation of the switching element 23. It has a capacitor 3 that stores the direct current given from the circuit, and the charging time of the capacitor 13 is controlled so as to be inversely proportional to the load current, and after the charging of the capacitor 13 is completed, a tripping signal to the circuit play force is generated. It is characterized by comprising a time delay circuit for giving a time delay to the tripping characteristic, and the current setting circuit and the time delay circuit are connected in series to the output of the first current transformer. .

Embodiments of the circuit play force tripping device according to the present invention will be described below with reference to the drawings.

In FIG. 2, a single-phase AC power supply 1 is connected to a load 3 via an NFB 2. A current transformer (first current transformer) 4 is installed on the line that supplies power to the load 3.
A single-phase full-wave rectifier 5 is connected to. A smoothing capacitor 6 is connected to the DC output side of the full-wave rectifier 5. Therefore, a DC voltage proportional to the load current appears across the capacitor 6. This DC voltage is applied to resistor 7
The voltage is applied to a series circuit consisting of a constant voltage diode 8 and a diode 9 via a voltage regulator diode 8 and a diode 9. The voltage of this series circuit is applied to the series circuit of PUTI I and relay 12 via diode 10. Here, the diode 10' functions as a limiter, allowing a reverse current smaller than the forward current to flow. Further, the relay 12 has a contact 12A, and when energized, the contact 12A is closed to energize the voltage tripping coil of the NFB 2, thereby tripping the NFB 2. A capacitor 13 and a resistor 14 are connected in parallel to the series circuit of the PUT II and the relay 12, respectively. On the other hand, the series circuit of the constant voltage diode 8 and the diode 9 includes resistors 14' and 15'.
A series circuit consisting of a constant voltage diode 16 and a constant voltage diode 16 are connected in parallel, and the gate G of PUT II is connected to the connection point with the resistors 14' and 15'. By the way, an auxiliary current transformer (
A second current transformer) 17 is installed. The output of this auxiliary current transformer 17 is applied to a single-phase full-wave rectifier 18. A variable resistor 20 and a smoothing capacitor 9 are connected to the DC output side of the single-phase full-wave rectifier 18. Therefore, a DC voltage proportional to the current flowing through the current transformer 4 appears across the capacitor 9. This DC voltage is applied to variable resistor 2
A parallel circuit of 1 and a constant voltage diode 22, a diode 10, and a switching element (for example, a transistor) 2
3 and resistor 2.
4 and a variable resistor 25. The connection point between these resistors 24 and 25 is connected to the base of the transistor 23 via a constant voltage diode 26. In FIG. 2, the first load current detection circuit is composed of a first current transformer 4, a rectifier 5, and a capacitor 6, and the second load current detection circuit is composed of a second current transformer 1.
7, a rectifier 18 and a capacitor 19. In addition, the time delay circuit includes resistor 7, diodes 8, 9, 10, and PUT
I1, a relay 12, a capacitor 13, resistors 14 and 15, and a diode 16.
0, 21, diode 22, transistor 23, resistor 2
4, 25 and a diode 26. and the first
A silk current setting circuit and a time delay circuit are connected in series as loads to the secondary side of the current transformer 4, and the series connection point of the fog current setting circuit and the time delay circuit is connected to the diode 10. It has become. Next, the operation of the above embodiment will be explained.

Now, if the load current is below the rated current of NFB2, the voltage across the variable resistor 25 is changed to the constant voltage diode 26.
, and the transistor 23 is in an off state.

Therefore, diode 10 is also in an off state. Since the reverse resistance value of the diode 10 is much larger than the value of the resistor 14, the voltage between the anode A and the cathode K of the PUTI I is approximately equal to the voltage between the gate G and the cathode K of the constant voltage diode 16. lower than the voltage between. Therefore, PUTII remains off, relay 12 is not energized, and NFB2 does not trip because its contacts 12A are open. Load current is NFB2
When the rated current is exceeded, the voltage generated across the resistor 25 exceeds the voltage of the constant voltage diode 26, the constant voltage diode 26 is turned on, and current flows to the base of the transistor 23.

Therefore, the transistor 23 is turned on, and since a voltage is applied to the diode 1 in the forward direction, the diode 10 is turned on. Therefore, the capacitor 13 is charged by the almost constant voltage generated across the constant voltage diode 8 and the diode 9, and the PUTI
The voltage between the anode A and the cathode K of I gradually increases. This voltage is applied to the gate G and cathode K of PUTI I.
PUTII turns on when the voltage between This energizes the relay 12 and NF
B2 trips. In this way, a long time operation is performed. Here, the larger the load current, the more quickly the capacitor 3 will be charged, so PUTII
operation time becomes faster. This ensures that the inverse time characteristic is inversely proportional to the load current. When the load current further increases to several times the rated current or more, the lightning voltage across the variable resistor 21 becomes equal to or higher than the voltage of the constant voltage diode 22, and the constant voltage diode 22 is turned on. As a result, the collector current of transistor 23 increases rapidly, and capacitor 13 is instantly charged. Therefore P
UTII turns on instantly and trips NFB2.
This results in instantaneous operation. Here, the inverse time characteristic and the instantaneous tripping characteristic will be further described.

In addition, in FIG. 2, the (10) output side of the rectifier 18 → resistor 21 → diode 10 → transistor 23 → rectifier 1
Let us assume that the current flowing in the loop called (1) output side of 8 is 1, and the current flowing in the loop of (10) output side of rectifier 5 → resistor 7 → diode 10 → capacitor 13 → (1) output side of rectifier 5. 12. First, since there is the second current transformer 17, 12>1. 1 in current transformer 17
Since the number of secondary turns is greater than the number of secondary turns, the secondary current of the current transformer 17 has a rudder smaller than the primary current. The current 12 can also be passed in the direction.

When the magnitude of the 12 current sources is 12>1, 12=
It is possible to reduce the current of 1.

Therefore, when the NPN transistor 23 is switched on, a current of 12=1 flows. Therefore, the capacitor 3 can be charged by the current 12 (=1,) proportional to the main circuit current. Therefore, an inverse time characteristic is obtained. Furthermore, when the collector current is supplied to the transistor 23 via the constant voltage diode 22, the value of 1 increases, and the capacitor 3 due to 12 (=1,)
Since charging occurs instantaneously, instantaneous trip characteristics can be obtained when a large current flows through the main circuit.

FIG. 3 shows the operating characteristics A, B, and C of this embodiment, with the operating time T plotted on the vertical axis and the load current 1 plotted on the axis.

The rated current can be adjusted by changing the value of the variable resistor 20. In other words, it is possible to move the characteristic A in parallel in the C direction. The starting point of the long time operation can be changed by adjusting the variable resistor 25. Parallel movement from characteristic A to B direction is achieved by variable resistor 21.
This can be done by changing the charging current. As described above, according to the above embodiment, the adjustment range of the long-time operation and the instantaneous operation can be widened, and there are also the following advantages. In the above embodiment, an auxiliary current transformer 17 and a full-wave rectifier 18 on the secondary side of the auxiliary current transformer 17 are connected in series with the full-wave rectifier 5 between the secondary output of the current transformer 4 and the full-wave rectifier 5. A time delay circuit is connected to the load side of the full-wave rectifier 5, a dew current setting circuit is connected to the load side of the full-wave rectifier 18, and the lightning current setting circuit and the time delay circuit are connected in series. are doing.

The output of the current transformer 4 is a constant current source, and this current transformer 4
Even if the load (impedance) of the current setting circuit and time delay circuit connected to the current transformer 4 fluctuates, the same current proportional to the primary side of the current transformer 4 flows directly in series to the open current setting circuit and time delay circuit. . Since the lightning current setting circuit and the time delay circuit are connected in series in this way, even if the load (impedance) of the lightning current setting circuit or the time delay circuit changes, the secondary output current of the current transformer 4 will not change. There is no error in the characteristics of each circuit, and highly accurate, stable characteristics and highly reliable characteristics can be obtained. Moreover, since the haze setting circuit and the time delay circuit are connected in series, even if there is an impedance change in the haze flow setting circuit by adjusting the current setting circuit, it will not affect the time delay circuit. Even if there is a change in impedance in the extension circuit, it does not affect the current setting circuit. Therefore, a circuit configuration can be formed to obtain the characteristics of the time delay circuit or the lightning current setting circuit alone, and therefore the circuit configuration is simplified, and the circuit configuration is small, inexpensive, and has improved reliability. Furthermore, the current setting circuit does not use characteristics that indicate negative resistance, and the time delay circuit starts operating only when the load current is above the set value, and then when the load current falls below the set value, the time delay circuit starts operating. Since the operation of the circuit is stopped during starting, there is no possibility of nuisance tripping due to inrush current of the motor at the time of starting, for example. In the above embodiments, the case where the power source is single-phase has been described, but the present invention can also be applied to the case where the power source is three-phase. In this case, the three current transformers 4 detect the load current flowing through the three-phase AC power line, and then convert it to direct current using the three-phase rectifier and feed it to the time delay circuit. current transformer 4 by current transformer 17
If the configuration is such that after detecting each of the secondary currents, the three-phase rectifier converts the current to direct current and supplies it to the haze current setting circuit, the same operation and effect as described above can be obtained. As described above, according to the present invention, a time delay circuit is formed on the secondary side of the first current transformer via the rectifier, and a time delay circuit is formed on the secondary side of the second current transformer in series with the rectifier. Connect a second current transformer so that Since it is connected in series, the adjustment range is wide and it can be used for NFBs having various rated currents.

Moreover, the secondary output rectified DC current of the first current transformer directly flows in series to the current setting circuit and the time delay circuit. Here, since the output of the current transformer is a constant current source, even if the load (impedance) of the serially connected dew current setting circuit and time delay circuit changes, the secondary output current value of the first current transformer does not change, therefore, there is no error in the characteristics of the current setting circuit and the time delay circuit, and a simple and accurate tripping device can be provided. Furthermore, the current setting circuit does not have a negative resistance characteristic, which has the effect of eliminating the problem of tripping at startup in loads that generate inrush currents, such as motors, transformers, and capacitors. The effects of the present invention as described above can be summarized as follows.

In other words, conventionally, a torrent current setting circuit and a time delay circuit were connected in parallel to the output of a current transformer, which is a constant current source, so adjusting the silk current setting circuit changes the characteristics of the time delay circuit, and vice versa. Adjusting the time delay circuit changes the characteristics of the dew current setting circuit, and it takes a lot of time to set the current and time, which not only deteriorates the setting accuracy but also increases costs. In contrast, in the present invention, since the frost current setting circuit and the time delay circuit are connected in series, the characteristics of the time delay circuit do not change even if the lightning current setting circuit is adjusted, and the time delay circuit is further adjusted. Since the characteristics of the lightning current setting circuit do not change even when the current is applied, it is possible to achieve high-accuracy setting quickly, with high reliability, and to greatly improve economic efficiency.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the operating characteristics of a conventional tripping device, Fig. 2 is a circuit diagram showing an embodiment of the circuit play force tripping device according to the present invention, and Fig. 3 is an explanatory diagram showing its operating characteristics. It is a diagram. 1... AC power supply, 2... Molded case circuit play force (NFB), 3...
Load, 4, 17...Current transformer, 5, 18...
Full-wave rectifier, 1 1...N-gate complementary SCR (PUT), 1 2...Relay, 1
3... Capacitor, 20, 21, 25...
- Variable resistor, 23...Transistor (switching element). Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. In the stationary tripping device for a circuit breaker, which detects an alternating current load current with a current transformer and generates a tripping signal to the circuit breaker either in a timed or instantaneous manner depending on the magnitude of the detected value, as described above. The load current is the first
a first load current detection circuit that detects a current with a current transformer and then rectifies it with a rectifier to extract a direct current; a second load current detection circuit connected to the second current transformer and rectifying the output of the current transformer to take out the load current as a direct current; a current setting circuit having a switching element and a diode connected in series with the switching element that operates to flow a current proportional to the load current when the load current exceeds a set value; and an output side of the first load current detection circuit. A direct current is applied from the first load current detection circuit to a current equal to a current proportional to the load current flowing through the current setting circuit through the diode of the current setting circuit based on the on/off operation of the switching element. The device has a capacitor that stores current, and has a time delay in the tripping characteristic that brakes the charging time of the capacitor so that it is inversely proportional to the load current and generates a trip signal to the circuit breaker after charging of the capacitor is completed. a time delay circuit for setting the current, and the current setting circuit and the time delay circuit are connected in series with the output of the first current transformer via the diode. static type trip device.