I am replacing a DC power supply used in a lab experiment. We need to be able to choose a positive or negative current. Bipolar power supplies in our power range (around 1 kW) are expensive, so I am planning to buy two separate units: a unipolar supply, and another unit that will allow us to switch between the two polarities.
What is the name of that second component? Can I reasonably expect to get both from the same supplier?