Bench power supplies are available in variable or fixed voltage. A variable power supply will offer the ability to adjust the output, be that voltage, resistance, current or power and is ideal where versatility is required in an application, such as circuit testing. Variable power supplies have a feature called Current Limiting so it will shut down or limit current to the maximum rating. They normally have controls to allow the change of current from zero to the specified maximum current which helps to protect components.
Bench power supplies are available in two different designs:
Wondering how many channels you need? Will depend on how many supplies you want to use simultaneously, but at least two channels are normal practise for a bench power supply.