JPS6010582B2 - Constant current testing method for electrical equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a constant current energization test method for electrical equipment with excellent response.

Electrical equipment may be damaged or its characteristics may change due to heat or electromagnetic force caused by transient currents such as short-circuit currents or overload currents, and equipment may be destroyed by repeated intermittent currents.

In addition, there are cases where it is necessary to determine the operating characteristics of equipment due to the continuous current, and in order to verify these characteristics, it is often necessary to apply a constant current.

In this case, the voltage does not need to be as high as the rated voltage, but only a certain amount of current needs to be supplied.In order to reduce the equipment capacity and reduce power consumption, it is preferable to test at a low voltage. It's normal. Below, we will explain fuses as an example of equipment that is often tested at low voltage and constant current. Fuses are widely used to protect electrical equipment and power transmission and distribution systems. Before equipment or power transmission and distribution systems are destroyed, fusible materials such as silver wires are melted, the arc is extinguished by the arc extinguishing agent provided around the area, and the current is cut off. The relationship between continuous current and operating time (generally referred to as fusing characteristics) is the most important characteristic, and a constant current is required to verify it. Expansion and contraction (this is called a heat cycle) may eventually lead to melting.
Performance verification in this case is also performed by intermittent constant current.
This is the equipment that requires the most constant current for performance verification.

Here, FIG. 1 shows an example of a commonly used test method for fuse blowability.

In this diagram, T, , T2 are power supply terminals connected to a low voltage AC power supply of 100V or 200y. The low voltage is 0 to 400V via an induction voltage regulator or Slydac voltage regulator blind! This voltage is adjusted, and further transformed into a low voltage of 0 to 10V and a large current through a large current transformer 2, and then supplied to the fuse 3 under test. The current supplied to the fuse is checked by a detector 4, and the voltage regulator blade is adjusted by a regulator 6 to compensate for the difference between the current and the current set by the setting device 5, so that the current supplied to the fuse is always at the setting value of the setting device 5. Current values are maintained close to each other.

By the way, as shown in characteristic a in Figure 2 (a diagram to explain the necessity of rapidly increasing the power supply voltage when a constant current is applied to a fuse), the temperature of the fuse increases as the current is applied. Along with this, the electrical resistance of the fuse 3 under test increases as shown by characteristic b in FIG.

In this case as well, since the resistance of the fuse under test accounts for most of the impedance of the test circuit, if the voltage is kept constant, the current decreases as shown in characteristic c in FIG. 2.

Therefore, in order to keep the current constant at the set value as shown in characteristic d in Figure 2, the power supply voltage must be increased as shown in characteristic e in order to compensate for the difference between characteristics d and c. Ru. However, with this method, even conventional induction voltage regulators and voltage regulators such as Sly-Dac have a slow response and cannot follow rapid resistance changes lasting less than a few seconds.

In such cases, tests are conducted at high voltages as shown in FIG. In other words, "Power terminal T2
Even if a high voltage of 3000V or 6000V is applied between them, the voltage is transformed into a large current of 100 to 1000V by lightning.
It is designed to supply current to.

In this case, the impedance of the test circuit is mostly accounted for by the external load 8 for current adjustment, and even if the impedance of the fuse 3 under test changes, a constant current is supplied to the fuse 3 under test.

However, with this method, ``installed capacity and power consumption are
This is 10 to 10 times more expensive than the low voltage, high current test method shown in the figure, and the equipment costs and test costs are enormous.

This invention was developed in consideration of the above points, and was developed by providing a transformer with a large number of taps and switching the taps with a bidirectional thyristor instead of a conventional induction voltage regulator or Slydac type voltage regulator. The present invention provides a constant current energization test method for electrical equipment that enables low voltage, high current testing with excellent response.

Next, an embodiment of the constant current energization test method for electrical equipment of the present invention will be explained based on the drawings. Figure 1 is a circuit diagram showing a test device applied to the embodiment. T1 and T2 are power supply terminals, and
A low-voltage AC power supply of V or 200 V is connected, and the primary winding of the control transformer is also connected.

The secondary winding of this control transformer g has many taps A.
,,A2,n,... each tap A, mackerel
A28 A3q, · is bidirectional thyristor B, mother &? They are commonly connected to a connection point P, via...

"One end of the secondary winding of the control transformer g (lower end of the figure)
and connection point PI are connected to both ends of the X-order winding of the large current transformer 2. The fuse under test 3 is connected to both ends of the secondary winding of this large current transformer.
A current transformer CT is provided between the fuse 3 under test and one end of the secondary winding of the large current transformer 2.

The output side of this current transformer CT is connected to the detector 4', and the detector 4' is also connected to the setting device S, so the output side of this detector 4 is connected to the regulator mouse. Q: Is the output side of this regulator 8 connected to the above-mentioned bidirectional syringe B,? B2,
B39... Ants are competing with each gate of the Q ogi.The test equipment configured as described above is also used to explain the case where the constant current energization test method for electrical equipment of this invention is performed.First of all, the power supply Fox OV or 20QV on terminal T tatami Q T2
By connecting a low-voltage AC power source, current is supplied from the control transformer 9 and each bidirectional thyristor B, B2, public, . . . to the fuse under test 3 via the large current transformer 2.

Even if the current flowing through the fuse 3 under test is detected by the current transformer C, the output of the current transformer CT is supplied to the detector.

The detector 4 is also supplied with the setting value set by the setting device 5, and therefore the detector 4 checks the output of the current transformer CT and the setting value of the setting device 5 and adjusts the setting value according to the difference. The output is sent to the regulator 6. Accordingly, the regulator 6 sends a switching signal to the gate of the bidirectional syringe connected to the tap of the secondary winding of the control transformer 9 according to the above difference. , by switching the bidirectional sirens
Always kept close to the set value.

At this time, the tap switching order is, for example, tap A,
Rather than switching intermittently like "Fu, A3...", "Tap A, 1 A, 10" (indicates that the taps are energized in parallel).

The same applies hereafter) -A2-A2-~ The test accuracy is better if adjacent taps are overlapped and switched continuously. In addition, when the current changes significantly, such as when starting a thin current, if the taps adjacent to the bottom tap were rounded up sequentially, it would take a long time to reach the set value, resulting in extremely poor response. It becomes evil.

In such a case, a method for reaching the target tap most quickly is shown in FIG. That is, this is a method in which a small current 1, which does not interfere with the testing of the device under test, is passed for a short time, the current is detected, a tap is calculated to set the set value to 12, and the tap is switched to that tap.

The inventors of the present invention have succeeded in obtaining a high response of about 0.09 sand to reach a set point of 95% using this method. In addition,
The above embodiment is merely an example, and it goes without saying that various improvements and modifications can be made within the framework of the present invention.

As described above, according to the present invention, low voltage with a long response,
When a large constant current is obtained and the electrical resistance of the device under test changes rapidly, tests that were conventionally performed at high pressure can now be performed at low voltage, reducing equipment capacity and power consumption. This provides the advantage of being able to perform economical testing.

Brief explanation of Kannami Figure 1 is a circuit diagram showing the test equipment applied to the conventional low voltage constant current energization test method for electrical equipment, and Figure 2 is a circuit diagram showing the test equipment applied to the conventional low voltage constant current energization test method for electrical equipment. Figure 3 is a circuit diagram showing a test device applied to a method for testing electrical equipment with a constant current at a high voltage, and Figure 4 is a diagram for explaining the necessity of increasing the voltage to FIG. 5 is a circuit diagram of a test device applied to an embodiment of the constant current energization test method for electrical equipment, for explaining a method for obtaining a high response at the start of energization in the constant current energization test method for electrical equipment of the present invention. This is a diagram.

2... Large current transformer, 3... Fuse under test, 4... Detector, 5... Setting device, 6... Adjuster, 9... Control transformer, A,, A2,... Tap, B, B2, B,
...Bidirectional thyristor CT...Current transformer.

Note that the same reference numerals in the figures indicate the same or equivalent parts.
Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. The primary winding of the control transformer is connected to a low-voltage AC power supply, and the secondary winding is provided with a large number of taps, each of which is connected to a bidirectional thyristor, and the bidirectional thyristor is connected to the secondary winding. supplying current from the bidirectional thyristor to the device under test via a large current transformer, detecting this current with a detector, and selectively firing the bidirectional thyristor according to the difference from a set value. Switch the above tap to supply a constant current to the device under test, and also supply a small current that does not interfere with the test of the device under test when the device under test starts energizing or when the current changes significantly. A constant current energization test method for electrical equipment characterized by energizing for a short time, detecting this current, calculating a tap to set the current value according to the difference from the set value, and switching to that tap. 2. Claim 1, characterized in that the device under test uses a fuse, and the fuse is subjected to a fusing characteristic test, a temperature rise test, and a heat cycle test.
Constant current energization test method for electrical equipment described in Section 1.