FAQ

Power Supply

1) What kind of power supply should be used?

Many applications work fine with a simple open-frame bulk power supply, which is basically just a huge transformer followed by a rectifier and filter capacitor.

However, the simple bulk power supply suffers from a couple of disadvantages: first, the simple bulk supply is very heavy due to the huge iron transformer; and secondly, it draws very high peak currents from the power line which may, at high power levels, result in mysteriously blown circuit breakers and/or overheated wiring.

Switching type power supplies solve both the weight and the current pulse problems, although a switching supply may be considerably more costly.

Batteries are an excellent power source, although they are not practical for all applications. In systems with high surge currents and/or voltage transients, batteries can be used to meet the surge demands and absorb the transients, while a dc power supply can provide the normal operating current and a trickle charge for the batteries.
 

2) The output of my 24 volt bulk power supply suddenly jumps up to over 30 volts and the system shuts down... what's the problem?

In some systems, due to inertia or mechanism mass, the motor can become a generator and attempt to deliver power back to the power supply.

With batteries as the supply, the batteries are simply recharged by this transient condition. But when an electronic power supply is used, this "reverse" power can severely damage the power supply and/or servo controller.

For design tips and more details about this potentially hazardous situation, please go to the web page that has the Motor/Mechanism FAQ.