OLTC are classified as Uni directional OR Bi dircetional depending upon its capacity of transition resistance to deal with current experienced while raising and lowering taps in relation with direction of power flow.
A unidirectional designed OLTC for power flow from HV to LV side across entire tap range in raise/ lower direction; may not be suitable on all taps if used for LV to HV power flow
It is therefore recommended to us a bi directional OLTC so transformer can be used fully on all taps as step down or step up mode
Bidirectional OLTC in Transformer
Re: Bidirectional OLTC in Transformer
