JP2786984B2 - Load testing machine for three-phase alternator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load tester for a three-phase alternator. 2. Description of the Related Art Conventionally, in an output (performance) test of a stationary power generation facility or a portable power generator with an engine, the number of phases of the power generator in a water tank filled with salt water as a resistor is known. The same number of electrodes as above were suspended, and the test was performed while adjusting the resistance by raising and lowering the electrodes to change the flooded area. [0003] However, the current density in the salt water near the electrode is extremely high, and the salt water in this portion boils in a short time, the resistance value becomes unstable, and only the instantaneous performance is measured. However, there were drawbacks in that accurate data could not be obtained and reproducibility was poor. Accordingly, in the present invention, a resistance circuit is connected to an input terminal for connection to a three-phase alternating current generator to be tested via a switch so as to be intermittently connectable. Connect one end of each set of three resistors to the outlet, and connect the other end of each resistor to the input terminal via a star-delta starter.
An intermediate outlet is connected in the middle between the delta starter and the input terminal, while each resistor is provided with a plurality of taps, and each tap is connected to each of the plurality of outlets. The jumper cord connected to the intermediate outlet can be connected freely, and the set of three resistors can be switched between the star connection and the delta connection by the star / delta starter and connected to the three-phase AC generator. A feature of the present invention is to provide a load test machine for a three-phase alternating current generator. An embodiment of the present invention will be described in detail with reference to the drawings.
In FIG. 1, A denotes a load tester for measuring the performance of a three-phase AC generator. A substantially rectangular parallelepiped case 2 is mounted above a base 1, and three cases are provided inside the case 2. One set of resistors 3 accommodates two sets and a cooling fan 4, and an input terminal 6 for connecting a measurement controller 5 and a generator to be tested and a jumper cord on the outer surface of the case 2. An outlet 7 is provided. As shown in FIGS. 2 and 3, the resistor 3 is formed by stacking a large number of resistance elements 8 formed in a substantially meandering shape while maintaining a predetermined interval, to form one grid-shaped resistor. doing. [0007] Three bolt insertion holes 8a are formed in the resistance element 8, and insulating bolts 9 for assembly are inserted through the insertion holes 8a. The mica is burned for. In the figure, reference numeral 10 denotes an annular insulating ring;
Denotes a conduction ring, an insulation ring 10 is provided at the center of the three insulation bolts 9 at all intervals of the stacked resistance elements 8, and an insulation ring 10 is provided at the remaining two insulation bolts 9 at both ends. By alternately inserting the insulating ring 10 and the conductive ring 11 at the same interval, the stacked resistive elements 8 are connected in an electrical series state. In addition, the resistance element 8 in the middle of stacking includes:
A plurality of taps 12 are connected in series so that a current can pass from the middle of the resistor 3. [0010] Then, three such resistors 3 are arranged in the upper and lower three stages close to the inner surface of the case 2, one end of each resistor 3 is connected to the leftmost outlet 7, and the other end is connected to the star. It is connected to the input terminal 6 via the delta starter 13. This circuit branches between the input terminal 6 and the star / delta starter 13 and is connected to the intermediate outlet 14, and a detachable jumper cord 15 is provided between the intermediate outlet 14 and the outlet 7. And both outlets 14 and 7 are connected. Note that the resistors 3 can be arranged side by side in three rows. In this case, each resistor 3
Are arranged upright and arranged in three rows. The star / delta starter 13 includes a star connection contact MSY1 and a delta connection contact MS # 1, and is configured so that both contacts are not closed at the same time. The resistance circuits R1 and R2 are connected to the input terminal 6 in parallel. The measurement controller 5 has a push button switch 5b for starting and stopping, a voltmeter 5c, and a frequency meter 5d on a front door 5a.
Inside, a control circuit 5e shown in FIG. 6 is provided. In FIG. 6, T is a timer and the same contact, MS △.
1, MS △ 2 are delta connection relays and contacts, MSY
1, MSY2 is a star connection relay and contact, PB1,
PB2 is a start button switch, CB1 and CB2 are stop button switches, 5d is a frequency meter and contacts, TS is a tumbler switch and its contacts, AR is a holding relay and contacts E1 and E.
Reference numeral 2 denotes a power supply, which is connected to a point which is not affected by the switching of the generator to be measured. The taps 12 provided on the resistor 3 are connected to the outlets 7a, 7b, 7c, respectively, so that different electrical resistances can be obtained by replacing the jumper cord 15. . The embodiment of the present invention is configured as described above. When the performance test of the three-phase AC generator is performed by the load tester A according to the embodiment, the three-phase AC When a switch (not shown) is connected to the input terminal 6 and the start pushbutton switch PB1 is pressed to close the contact, the timer T is started and connected to the generator in a star connection state. Heat is generated to reach a so-called saturation temperature at which a change in resistance value with respect to a temperature change becomes extremely small. At this time, if the timer T started simultaneously with energization is set to a time slightly longer than the time to reach the saturation temperature in advance, when the set time is reached, the star connection relay MSY1 is opened and the delta connection is opened. Is closed, and each resistor 3 is connected to the three-phase AC generator in a delta connection state. Next, with the power of the three-phase AC generator measured as described above, first, at the star connection power, that is, about 60% of the power at the time of the delta connection, the resistance value of each resistor 3 is changed. Is preheated until the temperature becomes stable, and the preheating end timer T automatically switches to delta connection and performs measurement.
Stable performance measurement becomes possible. Further, by replacing the jumper cord 15, the resistance value of each resistor 3 can be increased or decreased stepwise. In this embodiment, each of the outlets 7a, 7b, 7c of each of the resistor circuits R1, R2 is connected. On the other hand, each tap 12 is connected so as to have a resistance value suitable for the power measurement of 75, 100, and 125 KVA.
When 1 and R2 are in a parallel state, power measurement of 150, 200, and 250 KVA can be performed. According to the present invention, the following effects are produced. That is, when the load tester is started after the three-phase AC generator to be tested for performance is connected to the input terminal, a set of three resistors in the resistance circuit is connected to the generator. . At this time, a set of three resistors in the resistor circuit can be first star-connected by a star-delta starter, and then switched to a delta connection. Accordingly, with the measured power of the three-phase AC generator, first, preheating is performed until the resistance value of each resistor is stabilized at the power of the star connection, that is, about 60% of the power at the time of the delta connection. Then, by switching to the delta connection and performing the measurement, stable performance measurement can be performed. By connecting jumper cords to a plurality of outlets, the resistance value of each resistor can be increased or decreased step by step. Performed performance measurement can be performed quickly and accurately.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall side view of a generator tester having a resistor according to the present invention. FIG. 2 is a front view of the same. FIG. 3 is a front view of a resistance element. FIG. 4 is a side view of the resistor. FIG. 5 is a resistance circuit diagram. FIG. 6 is a control circuit diagram. FIG. 7 is an explanatory front view of a resistor as another embodiment. [Explanation of symbols] 8 resistance element 12 taps

Claims (1)

(57) [Claims] Connect a resistor circuit (R1) to the input terminal (6) for connection to the three-phase AC generator to be tested via a switch so that it can be intermittently connected.The three resistor circuits (R1) are connected to the outlet (7a). A set of resistors
(3), (3), (3) with connecting each one end of the input the resistors to the terminal (6) (3), (3), star Del the other ends of the (3)
Connected via a starter (13)
An intermediate outlet (14) is connected midway between the starter (13) and the input terminal (6), while each of the resistors (3), (3), and (3) has a plurality of taps (12 ),
(12), each tap (12), (12) is connected to a plurality of outlets (7b), (7c), respectively, and each outlet (7a),
To (7b) and (7c), connect the jumper cord (15) connected to the intermediate outlet (14) freely and replace it , and use a star-delta starter (13) to set a set of three resistors.
(3) (3) (3) is switched between star connection and delta connection
A load tester for a three-phase alternator, which can be connected to a three-phase alternator.