JPS6230386B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrical load device used for testing the possibility of maintaining stable operation of electrical equipment during instantaneous drops in power supply voltage.

Recently, power supply devices such as constant voltage constant frequency power supply devices, thyristor Leonard devices, and Servius devices have come into widespread use in various industries. On the other hand, an accident in other equipment connected to the same power supply system may cause an instantaneous voltage drop in the power supply system, making the operation of the constant voltage constant frequency power supply equipment etc. connected to this power supply system unstable. Become or stop. Such a situation also occurs due to an instantaneous drop in the power supply voltage during a power failure. In general, in order to achieve stable operation of electrical equipment, it is extremely important to stabilize the input power supply voltage. However, fluctuations in power supply voltage can always occur unexpectedly, and the extent of the fluctuation is important. may not always be within the allowable range of design specifications. As a result, the electrical equipment cannot continue to operate. Therefore, it is important to conduct tests as a means of maintenance of operation to determine to what extent such electrical equipment can actually continue stable operation up to the above-mentioned fluctuations. That is,
It is necessary to confirm the voltage drop rate and voltage drop time for which electrical equipment connected to the power supply system will operate stably. Such confirmation will ensure the reliability of electrical equipment and provide guidelines for countermeasures.

For this reason, various maintenance test equipment for measuring the voltage drop rate, etc. of the above-mentioned electrical equipment has been proposed, and the electrical load device shown in Fig. 1, which is required when performing this test, has come to be widely provided. There is.

This is a parallel circuit consisting of a shield breaker 1, an electromagnetic contactor 2, and a series impedance 3, a power supply device 4 such as a thyristor Leonard device, and a load 5 connected in series from the power input side. As shown in the figure, a voltage drop resistor 7 is connected via an electromagnetic contactor 6. This electric load device simulates the drop in the power supply voltage mentioned above, and the electromagnetic contactors 2 and 6 are opened and closed equally as shown in Fig. 2b and c, respectively, and the power supply input voltage is changed as shown in Fig. 2a. It operates as if it were to be lowered instantaneously.

However, with the above circuit using the electromagnetic contactors 2 and 6, a simultaneous three-phase instantaneous power outage test is easy;
When testing arbitrary phases, it is necessary to install one single-phase magnetic contactor for each phase, which makes the equipment large-scale and expensive. Also, when the series impedance 3 that determines the voltage drop rate is increased,
Although the power consumed by the resistor 7 can be reduced, the distortion of the power supply voltage waveform becomes large, and the equivalence of the test is lost. Furthermore, in determining the voltage drop rate, it is necessary to adjust the power consumed by the drop resistor, and this operation lacks speed.

The present invention was made in view of these conventional problems, and in particular, connects a series impedance and an electromagnetic switch connected in parallel to the input side of a power supply device, and furthermore connects a large impedance drop in parallel to these. By connecting the load circuit that generates the voltage, it is possible to perform an instantaneous drop of the power supply voltage quickly and effectively, and by controlling the load circuit with a thyristor of the inversion circuit, the voltage drop rate can be set in three phases. To provide a novel electrical load device that can run simultaneously or on any phase by phase basis.

An embodiment of the electric load device according to the present invention will be described below with reference to the drawings.

In FIG. 3, a transformer 8, an inverter 9 consisting of a thyristor, a DC reactor 10, and a forward converter 11 consisting of a diode are connected to a magnetic contactor 2 and a series impedance 3 on the input side of a power supply device 4 similar to the above. They are connected in parallel. Here, the series impedance 3 above is 0.1
With an impedance of about ~1Ω, the electromagnetic contactor 2 short-circuits this during normal times, and opens the short-circuit during testing.

In such a circuit, in order to simulate a momentary power outage, first the electromagnetic contactor 2 is opened and the gates of the thyristors forming the inverter 9 are controlled.
This increases the inverter current, increases the voltage drop due to the series impedance 3, and determines the drop rate of the power supply voltage for the power supply device 4. In this case, by operating at least the inverter 9 as a separately excited inverter even when the electromagnetic contactor 2 is closed, gate control is performed at the same time as the electromagnetic contactor 2 is opened, and any of the above You can get the rate of descent. Thus, by setting the gate control angle of the thyristor arbitrarily and for each phase, it is easy to control the same rate of descent for three phases at the same time, or to control the rate of descent for only an arbitrary phase. In this case, if the forward converter 11 is replaced with a thyristor instead of a diode, the gate control angle can be unbalanced and the drop rate can be varied for each arbitrary phase.

As described above, according to the present invention, a parallel circuit consisting of a switch and a series impedance is connected in series to the input side of a power supply device connected to a power source, and an inverter and a forward converter are connected to these parallel circuits. By connecting load circuits connected in parallel through DC reactors, each phase gate of the inverter is controlled at the same time as the switch is opened to simulate an instantaneous drop in the power supply voltage to the power supply device due to a large impedance drop. The stable operation test of electrical equipment based on the voltage drop of each phase can be performed reliably with a simple configuration, and is extremely useful in practice as an actual load test means for diagnosing the operational reliability of electrical equipment.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a conventional electrical load device, FIG. 2 is a signal waveform diagram of each part of the circuit, and FIG. 3 is a circuit diagram of an electrical load device according to the present invention. 2...Switch, 3...Series impedance, 4...Power supply device, 9...Inverter, 10...DC reactor, 11...Forward converter.

Claims (1)

[Claims] 1 A parallel circuit consisting of a switch and a series impedance is connected in series to the input side of a power supply device connected to a power supply system, and an inverter and a forward converter having a control gate for each phase are connected to the above-mentioned circuit via a DC reactor. An electrical load device characterized by being connected in parallel to a parallel circuit.