JPH025421Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a testing device for large-capacity power supplies such as static uninterruptible power supplies.

BACKGROUND ART In recent years, large-capacity AC or DC power supplies, such as static uninterruptible power supplies installed in computer systems, are often used in various systems. Failure of these power supplies will lead to system failure, so
Of course, when installing equipment into a system, testing is required to ensure that the performance after installation maintains the originally guaranteed value.

Conventional test equipment for large-capacity power supplies, for example,
To test a static uninterruptible power supply with 50KVA and load power factor of 80%, connect a 40KW (50KVA x 0.8) resistor as a load or as an AC input voltage adjustment element.
By suddenly changing the resistor, performance items such as output voltage transient characteristics and settling time for ±50% load fluctuations or ±10% input fluctuations were checked. Therefore, it is necessary to prepare a large resistor with a variable resistance value as a dummy load for power supply testing, which is inconvenient as it takes time to move the test equipment and configure the test circuit required to check the performance of a large-capacity power supply. In particular, maintenance and inspection of power supplies requires transporting heavy test equipment to the power supply installation location.
If other equipment is installed near the power supply, it may not be possible to use a large resistor.

The present invention provides at least one electric motor as a dummy load or input voltage regulating element of the power supply,
Utilizing the large starting current of this motor and the controllability of starting current by changing the motor load, it is possible to impose a predetermined load on the power supply or change the AC input voltage, making it easy to move, connect, and test the equipment. The purpose is to provide a small-sized test device with

FIG. 1 shows an embodiment of the present invention, in which four induction motors are provided. In the same figure, the test equipment indicated by dashed-dotted line blocks includes four induction motors IM ₁ to _{IM 4} and a power supply terminal connected in parallel between the power terminals of these motors IM ₁ to IM ₄ and the device input terminal P1.
It is equipped with switches S ₁ to _{S 4} for disconnection. Electric motor IM ₁
~ If necessary, at least one IM ₄ is equipped with a brake BR, such as an eddy current brake, which also serves as a flywheel effect to adjust the starting current value and starting time. Further, the electric motor is configured so that the brake BR and the flywheel can be coupled separately, and the inertia of the flywheel can be adjusted to obtain the required load current according to the power source. The switches S ₁ to _{S 4} are selectively or continuously controlled to be turned on and off or manually operated depending on the load current and load current change characteristics required for the power supply test. In addition to the illustrated electric motor and switch, the test equipment includes measuring instruments such as a voltmeter that measure and record the output voltage and input voltage of the test power source, either integrally or separately.

In a test apparatus having such a configuration, the electric motor and the switch means are connected to the test power source as a dummy load of the test power source or as an AC input voltage regulating element. Figure 1 shows the case where the thyristor type variable voltage/variable frequency power supply CVCF is connected as a dummy load.
Connect the output terminal of the CVCF to the input terminal P1 of the test equipment, and selectively or continuously turn on/off the switches S ₁ to S ₄ .
By disconnecting the load current of the test power supply CVCF from the motor
Load as starting current for IM ₁ to _{IM 4} .

In addition, for tests in which the AC input voltage of the test power supply CVCF is changed, a test equipment is connected in parallel with the power supply CVCF as the load of the transformer T, and by turning on the switch of the test equipment, the power supply input voltage is instantaneously dropped. Alternatively, let the voltage drop for a short time and measure the stability of the output voltage of the power supply CVCF at that time. In order to bring the power supply CVCF to the rated load state during a stability test where the input voltage is changed, it is necessary to prepare two test devices, one as an input voltage adjustment element and the other as a dummy load, or use one test device as a dummy load. Some of the multiple electric motors included in the device are used as input voltage adjustment elements,
The input terminals of switches S ₁ to _{S 4} are pulled out separately so that the remaining motors can be used as dummy loads.

In this way, by preparing a motor as a dummy load of the test power supply or as an input voltage adjustment element, and controlling the connection between the motor and the power supply for a short time, tests can be carried out in which the starting current of the motor is used as the load current or input voltage change of the power supply. becomes possible. The starting current of the motor is 6 to 10 times the rated current, and the current during this starting time can be used to construct a compact test device that allows various performance checks of the test power source. for example,
A test equipment equipped with two 0.75KW motors is sufficient for testing a 50KVA capacity power supply. In other words, the input capacity of a motor has a steady state capacity and a starting capacity, and if the rated output of the motor is PKW, the steady state input capacity is P/
If the starting current is 10 times that of (P x f x η) and P f = 0.5 and η = 0.6, the input capacity at starting will be 10P/(0.5 x 0.6) = 33.3 x P (KVA). Become. Therefore, if the motor has a rated capacity of 0.75KW, the starting input capacity will be 33.3 x 0.75≒25 (KVA), and for this motor, the input capacity will be 33.3 x 0.75≒25 (KVA).
A 50% load change can be given, and two electric motors are sufficient for 100% load change.

Further, by program control of the switches _S1 to _S4 , it is possible to conduct a test in which the load current of the power supply CVCF is varied in a ramp function manner as shown in FIG. That is,
At time t ₁ , switch S ₁ is turned on and then at time t ₂
By sequentially turning on the switches _S2 to _S4 at ~ _t4 , it is possible to impose a stepwise load change in which the starting currents of the respective motors are sequentially added. Further, after time _t5 during the motor starting period, by controlling the switches _S4 to _S1 to open in the order opposite to the above-mentioned control, it is possible to change the load stepwise from maximum load to no load.
As shown after _t6 in Figure 2, even if the switches _S1 to _S4 are left in the on state, the starting time of the motors _IM1 to _IM4 is
The current decreases one after another by _tM , and finally becomes a test load equivalent to the sum of the steady current of each motor, and can be used for short-time load tests or input voltage fluctuations only by controlling the switching on of switches _S1 to _S4 . Testing becomes possible.

In addition, during the settling time test for sudden load changes on the test power supply, if the motor starting time _tM is smaller than the power supply settling time _tS , an inertial element such as a flywheel prepared on the motor is connected, and GD ² is adjusted. Increase the starting time t _M by . This starting time t _M
is determined by the accelerating torque of the electric motor and the flywheel effect GD ² of the rotor and load, and the motor rotation speed is n
(rpm), the average acceleration torque during starting is T (K _g − m)
Then, the starting time t _M can be obtained approximately from the following equation, and any load waveform can be obtained by adjusting GD ² and further combining the brakes BR.

t _M = GD ²・n/375・T [sec] In addition, although the test equipment for AC power supply is shown in the example, the present invention is not limited to this, and can also be used for independent testing of converter or inverter of uninterruptible power supply. is equipped with a DC motor and an AC motor, the DC motor is connected to the DC input/output part of the power supply, and the AC motor is connected to the AC input/output part of the power supply. The device can be realized.

In addition, AC motors have different starting characteristics, such as squirrel cage induction motors, reaction motors, and permanent magnet motors.
The electric motor can be selected as appropriate depending on the test content to be imposed on the test power supply.

As described above, the test device according to the present invention utilizes the large starting current of the motor and its controllability to use the motor as a load device for the test power supply. Compared to an input voltage fluctuation test, load connection control can be easily performed in a relatively short time, and a small electric motor, that is, a test device can be constructed.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing one embodiment of the present invention;
The figure is a waveform diagram showing an example of load control in the present invention. IM ₁ to IM ₄ ... Induction motor, S ₁ to _{S 4} ... Switch, CVCF ... Test power supply, BR ... Brake device.

Claims (1)

[Scope of utility model registration request] It is equipped with at least one electric motor and a switch that connects and controls the output terminal or input terminal of a test power source as a power source of the electric motor, and uses the load current or input voltage fluctuation of the test power source as the starting current of the motor. A test device characterized by testing load characteristics or input voltage fluctuation characteristics.