JPH0157310B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a testing device for circuits and breakers.

It is desirable that circuit breakers and breakers can be easily inspected without actually passing overload current through the load line during operation checks before installation in the power distribution system and periodic maintenance checks after installation. In particular, for line breakers that are equipped with an electronic control circuit that detects overload current in the load line and drives the tripping coil, inspection of the control circuit unit above, as well as this circuit, tripping coil, switching mechanism, contacts, etc. It is desirable to conduct a comprehensive inspection that includes the mechanical parts of the product, and to be able to easily and immediately confirm whether the defect is in the circuit or the mechanical part.

The present invention was devised to satisfy the above requirements, and will be described in detail below using Examples.

In FIG. 1, the test device 14 is provided with a changeover switch 3 so that a long time trip test or an instantaneous trip test can be selected. For the long time trip test, set the changeover switch to side a. When the power switch 16 is turned on, the AC 100V commercial power source 1 is transformed by the transformer 2, full-wave rectified by the rectifier 9, smoothed by the capacitor 10, and a voltage close to direct current is generated across the capacitor 10. This voltage passes through the resistor R1, causing the Zener diode _ZD1 to break down and making the transistor Tr1 conductive.
At this time, the collector current of the transistor Tr1 is a constant current determined by the constant voltage VZD ₁ due to the Zener diode ZD ₁ and the resistor R ₀ , so the resistor
By appropriately selecting R ₀ , the test device 14 can supply a simulated current i that corresponds to the detection current required for a long time trip test. Further, in the instantaneous tripping test, by turning the changeover switch 3 to the b side, the electric charge in the capacitor 10 is discharged through the resistor _R2 , and a simulated current larger than the above-mentioned long-time tripping current is instantaneously supplied.

Q ₂ is the resistance R ₁₃ between the simulated current supply lines 20 and 20'
The cathode side of the thyristor ZD ₂ connected via the light emitting part 19 is connected to the supply line 20,
A Zener diode with Zener voltage V ₃ whose anode side is connected to the supply line 20' via resistors R11 and R12, a capacitor 17 is connected in parallel to resistor R12, and the connection point of resistors R11 and R12 is connected to the gate of thyristor Q _2. Connected. 18 is a changeover switch connected between the gate of thyristor Q ₂ and the supply line 20'; when closed, thyristor Q ₂
The gate of is dropped to the potential of supply line 20'.

To explain the steady operation of the breaker, the load current of the load line 15 is detected by the current transformer 5 and the transformer 5', and this detected current is sent to the electronic control circuit 6.

Since the thyristor Q ₁ of the electronic control circuit 6 is initially non-conducting, the detection current i at the time of overload passes through the tripping coil 12 and the resistor R ₉ to the transistor Tr.
5 is made conductive, thus breaking down the Zener diode _ZD3 , and then the transistor Tr4 is made conductive. Here, the resistor _R9 is selected to be sufficiently large so that the current flowing through the tripping coil 12 is a minute current that only makes the transistor Tr5 conductive and does not cause the tripping coil 12 to operate.
If transistor Tr5 and transistor Tr4 are conductive and the low resistance values of resistor _R7 and resistor _R8 are selected to be sufficiently small compared to the internal resistance of time limit circuit 7, overload detection can be performed when the voltage is supplied from transformer 5'. current i
Most of the voltage flows through the resistor R7, the transistor Tr4, and the resistor R8, and the voltage V of the control circuit 6 is the sum of the Zener voltage VZD ₃ of the Zener diode ZD ₃ and the drop voltage VR ₈ of the resistor R ₈ , as shown in FIG. 2a. It becomes V ₁ .
When this voltage V ₁ is applied to the timer circuit 7, a trip signal is generated after a delay time to that depends on the magnitude of the current i (to becomes shorter as the current increases), and the thyristor Q ₁ turns on. arc. As a result of this firing, the forward voltage of the thyristor _Q1 becomes approximately 0.7V or less, transistors Tr4 and Tr5 are simultaneously turned off, and the impedance between the collector and emitter increases. For this reason, the current that has been flowing through the transistor Tr4 will now flow through the tripping coil 12. At the same time, the Zener diode ZD ₄ breaks down, and the voltage V of the control circuit suddenly rises to this Zener voltage.
The voltage increases by VZD ₄ , that is, the voltage V ₂ shown in FIG. 2a. Note that each Zener voltage is set so that V ₁ <V ₃ <V ₂ .

Therefore, at the same time as thyristor _Q1 fires, the second
As shown in FIG. c, the tripping coil 12 starts energizing and operates after a certain time _t1 (normally it takes 2 msec or more). The operation of this tripping coil activates the opening/closing mechanism of the shield breaker, and the shield breaker contact 4 opens and disconnects, cutting off the current to the load line. Note that the current in the tripping coil 12 temporarily decreases during the operation process, but this is due to the movement of the movable element 12'.

In addition, the breaker has a diode D ₀ connected in the forward direction to the detection current supply path of the control circuit 6, and has test terminals 13 at both ends of this diode.

In the case where the changeover switch 18 is opened in the above-described configuration, the operation of the test device and the breaker will be described. During the disconnection test, the output of the transformer 5' is temporarily short-circuited to stop supplying the detection signal to the control circuit 6.

The simulated current i supplied from the test device 14 is transmitted from the test terminal 13 of the breaker to the control circuit 6, and after a delay time t ₀ has passed in the timer circuit 7, the thyristor Q ₁ is fired by the tripping signal. . thyristor
When Q ₁ is fired, the voltage V of the control circuit 6 is the sum of the Zener voltage VZD ₃ of the Zener diode ZD ₃ and the voltage drop VR ₈ of the resistor R ₈ , as shown in Figure 3a.
Zener voltage of Zener diode ZD ₄ from V ₁
VZD tries to rise to voltage V ₂ increased by ₄ ,
The current flowing through the tripping coil 12 gradually increases.
The voltage V of the control circuit 6 is connected to the simulated current supply lines 20, 2
Since it is also applied to the Zener diode ZD ₂ via V 0', the Zener diode ZD ₂ breaks down when it rises to V ₃ and a voltage is generated across the resistor R ₁₂ , which causes the thyristor Q ₂ to fire. At this time, the resistance R ₁₃ in the test device 14 and the light emitting part 1
If the resistance value of 9 is set to be sufficiently low compared to the combined impedance of control circuit 6 and trip 2m, most of the simulated current i will flow through thyristor _Q2 ,
Only a small current i ₁ is supplied to the control circuit 6. Since the tripping coil 12 is an inductive load,
It takes t _{1 hour} (at least ₂ m
However, the Zener diode ZD ₂ and the thyristor Q ₂ of the test device 14 are turned on at t ₂ as shown in FIG. 4 after the thyristor Q ₁ of the control circuit 6 is fired.
The tripping coil 12 operates at extremely high speed (several μs or less) compared to the complete operating time of the tripping coil 12.

Therefore, when the test device 14 supplies the simulated current i to the control circuit 6 of the breaker, the thyristor _Q1 fires after a certain delay time (time _t0 in Fig. 2), and then the thyristor Q of the test device fires. ₂ is fired, almost no fault simulating current i is supplied to the control circuit 6, and the tripping coil 12 can be rendered inoperable. Furthermore, when the Zener diode ZD ₂ of the test device 14 breaks down, the light emitting section 19 connected in series with it emits light, so even if the mechanical section of the circuit breaker and the switching contacts do not open, the control circuit 6 You can check the disconnection function. Next, the operation when the changeover switch is closed will be explained. switch 1
When 8 is closed, the gate of thyristor Q ₂ of the test device 14 is short-circuited, and thyristor Q ₂ does not fire. The simulated current i is transmitted as it is (i≒i ₁ ) to the control circuit, and the tripping coil 12 operates with the current i ₂ and the shear cut-off mechanism works, causing the shatter-cutting mechanism including the control circuit and the shear cut-off mechanism. Functionality can be checked.

For monthly inspections, the switch 18 is left open and only the control circuit is inspected, and for annual inspections, the switch 18 is closed and the control circuit,
Inspect and confirm the shedding mechanism. As a result, it is possible to prevent the mechanical life of the contacts and mechanical parts from being unnecessarily shortened. Furthermore, if a defect is discovered during a trial inspection, it can be easily determined whether the cause is in the control circuit or the mechanism by performing the above two types of inspections.

Furthermore, during the instantaneous tripping test, an excessive current will flow through the light emitting section 19, which may destroy the light emitting element 19;
All you have to do is increase the resistance value of 2 appropriately.

As explained above, according to the present invention, it is possible to easily perform a test of each electronic control circuit of a shield breaker and a comprehensive test of the mechanical part and contact part including this control circuit by operating a changeover switch. In addition, this allows defects to be found immediately.

[Brief explanation of drawings]

Fig. 1 is a circuit configuration diagram of a test test device and a circuit breaker according to an embodiment of the present invention, Fig. 2 is a signal waveform diagram of each part of the control circuit, and Fig. 3 is a test test using a test test device according to an embodiment of the present invention. FIG. 4 is a signal waveform diagram of each part of the control circuit at the time. 2, 3, 9, 10, R ₀ , R ₁ , R ₂ , ZD ₁ , Tr ₁ :
Simulated current generation circuit, R ₁₁ , R ₁₂ , R ₁₃ , Q ₂ , ZD ₂ ,
17, 19: Control circuit, 3: Changeover switch, 5,
5': detection circuit, 6: control circuit, 12: tripping coil, 19: light emitting section.

Claims (1)

[Claims] 1 The load current flowing in the load line is detected by the detection means, the control circuit receives this detected current and generates a tripping signal at the time of overload, and based on this tripping signal, the tripping coil is driven to open the contact. In a test device that checks the operation of a control circuit by supplying a simulated overload current to a circuit or disconnector, the test device uses a simulated current generating circuit and a tripping signal generated from the control circuit after supplying the simulated current. a control circuit that operates before the tripping coil operates to limit the supply of simulated current to the breaker; a display that is driven based on the operation of the control circuit; and a display that operates the limiting circuit. A test device for a circuit or disconnection characterized by being equipped with a changeover switch that sets the switch to one of the disabled states.