Equipment

ECE401: Power Electronics

Figure 1. 3-Phase Resistor Load Box

3-Phase Resistor Load Box

The 3-Phase Resistor Load Box consists of 3 isolated resistor banks, ‘a’ the with red jacks, ‘b’ with black and ‘c’ with blue. The resistance of each bank is always equal and selected by using the 5 switches on the front of the box. Having all of the switches open or off means that the resistance of each load bank will be open or infinite. Closing any one of the switches will add a 150 Ω resistor between the terminals for each of the 3 banks. Closing a second switch will then add another 150 Ω resistor in parallel with the first meaning that there will now be a total of 75 Ω between the terminals of each bank. You can continue with this logic until all 5 switches are closed which will result in 30 Ω between the terminals of each bank.

As the banks are isolated you can use them in the following arrangements.

• Independently.
• In parallel to increase the resistance or the voltage carrying capacity.
• In series to decrease the resistance or the current carrying capacity.
• In a 3-phase wye connection.
• In a 3-phase delta connection (Caution as the bank is only rated for 180Vrms and most 3ph supplies are at least 208Vrms).

Note the following:

• Each bank is rated to handle 180Vrms
• The box consists of 3 banks of 5 resistors for a total of 15 resistors.
• Each individual resistor is a 150 Ω 225 W tubular resistor.
• A chassis ground connection is provided.

Note

The 3-Phase Resistor Load Box also has a chassis ground connection available on the front of the box which allows you to ground the enclosure for safety. The connection uses a green safety banana jack that should be connected to an earth ground which is typically available on one of the power supply boxes.

Videos

3 Phase Resistor Load Box .

3Ph Load Box Simulation

Go to full screen simulation .