Power supplies for electrophoresis are used to create the electrical current to power DNA/RNA separations, PAGE electrophoresis and transferring to membrane.
The voltage determines the scope of function with 300V strong enough for running gels while 250V is needed to perform transfers.
Additional features and considerations to look for when shopping for an electrophoresis power supply are:
Is the device cold room safe?
What is the longest time the power supply can run before automatically shutting off?
Is it programmable, and how many operations can be stored in the memory?
Stellar Scientific carries power supplies for electrophoresis from many recognizable brand names. Look for the ENDURO line by Labnet and the My Volt line from Benchmark/Accuris as well as others.