SafetyQuestion 433 of 521
You are servicing a circuit that feeds a variable frequency drive (VFD) with large DC-bus capacitors. After disconnecting power you must:
a.Immediately touch the terminals to test them
b.Ignore stored energy because it is a low-voltage system
c.Allow/assist the stored energy to dissipate and verify the capacitors are discharged before contact
d.Short the source to ground while it is still energized
Explanation
Capacitors in VFDs can hold a dangerous charge after power is removed, so you must let them discharge (per manufacturer's time/procedure) and verify they are discharged before touching. Touching immediately or ignoring stored energy risks a shock, and shorting an energized source is dangerous and can cause an arc flash.
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