There is a fixed single phase supply, a fixed three phase (3Æ) supply, and a variable 3Æ supply. The model also contains the MAIN A.C. circuit breaker and a pilot light.

The MAIN A.C. breaker is used to energize the three A.C. power supplies as well as the D.C. power supplies of Model HMD-100-PPC-DC. The pilot light is “on” as long as the MAIN A.C. breaker is “on”. The pilot light is located at the upper left portion of A.C. Power Supply Panel and below it is the MAIN A.C. breaker. To the right of the breaker is the fixed single phase (1Æ) power supply rated at 120V (line-to-ground). It consists of a duplex receptacle, like the typical wall receptacle found in any home. The fixed 3Æ supply is directly below the MAIN A.C. breaker and consists of four pin jacks labeled A, B, C. and N with colors red, blue, black, and white, respectively. It is rated at 240/140 volts, 6 amps, and 4 watts. The 240 volts is the line-to-line rating, i.e., the voltage between any pair of jacks labeled A, B, or C; and the 140 volts is the line-to-ground rating which is measured between pin jack A, B, or C and pin jack N. The variable 3Æ supply is below the fixed 3Æ supply and it consists of a three-pole circuit breaker (similar to the MAIN A.C. breaker), four pin jacks like those of the fixed 3Æ supply, and a voltage control knob. This variable supply is also rated at 240/140 volts, 4 watts, and 6 amps.

The last feature of the A.C. power supply panel is a green terminal label GND (ground) which is used to make circuit connections to a common ground for an experiment.

A.C. Power Supplies

CAUTION:

Before touching the supply or making any connections, make sure that the “MAIN A.C.” circuit breaker is OFF. Also make sure the breaker of the variable three phase (3Æ) supply is OFF.

1. Select the power supply appropriate for the experiment.

2. Connect the circuit or device to the supply using a plug for the fixed 1Æ supply and the appropriate leads for the 3Æ supplies. For the 3Æ supplies connect the phase A lead to the red pin jack and the other phase leads to their appropriate pin jack. If neutral is involved, use the white pin jack.

3. For the variable 3Æ supply, connect a voltmeter across the supply, i.e., between two phases (A, B, or C) or between one phase and neutral (N). These connections will probably be “piggy-backed” on the connections made in step 2.

4. Make sure the voltage control knob of the variable 3Æ supply is turned fully counter-clockwise, whether or not this supply is to be used.

5 “Turn on” the MAIN A.C. breaker.

6. If the variable 3Æ supply is being used, “turn on” its circuit breaker, then turn the voltage control knob to obtain the desired voltage.

7. If the supply is overloaded, a breaker should “trip” resulting in a power cut-off. If this occurs, place the MAIN A.C. breaker in the OFF position, and if the variable 3Æ supply is being used, turn the voltage control knob fully counter-clockwise and “turn off” its breaker. Then seek the assistance of your Lab Supervisor BEFORE YOU PROCEED.