Connecting Laboratory Power Supplies
Wednesday, March 13, 2019
10:02 PM
Most regulated DC power supplies used in the laboratories usually contain two separate, adjustable DC power supplies, isolated from one another and ‘floating’, i.e., not connected to earth. This is shown below:
Figure 4 – Dual Independent Power Supplies
The Siglent SPD3303C Series Programmable DC Power Supply used in the Lab can be placed in a mode called Series in which the previously independent power supplies are internally connected in series and effectively have one common terminal, as shown below:
Figure 5 – Series-Connected Dual Power Supply
There is also a third, switchable 2.5 V / 3.3 V / 5.0 V DC power supply, intended specifically for digital circuits. The Programmable DC Power Supply therefore looks like:
Figure 6 – Triple Independent Power Supply
For laboratory experiments, the 0 V “common” (wherever you decide that to be) must be connected to earth. Otherwise, the ‘floating’ supplies might pick up stray DC or AC voltages that could endanger the circuit you are studying, or yourself. For example:
Figure 7 – Dual Power Supply with Earth