OLTC

[RalphChristie]

Dear all

Is there any difference between a master/slave configuration and a master/follower configuration for OLTC's (onload tap changers) on parallel transformers, or is it the same?

If there is a difference, what is it, and why do they use it?

Many thanks

RCC

 

[jghrist]

Probably a method to remain politically correct.;-)

You think I'm kidding, but consider the following from a memo of the Los Angeles County Internal Services Department warning of offensive high-tech terminology:

"One such recent example included the manufacturer's labeling of equipment where the words 'Master/Slave' appeared to identify the primary and secondary sources. Based on the cultural diversity and sensitivity of Los Angeles County, this is not an acceptable identification label."

http://www.reason.com/hitandrun/003490.shtml#003490

 

[dpc]

As jghrist says, the term "master/slave" is being replaced by "master/follower". No difference in functionality.

 

[RalphChristie]

I've done some searching on google and found this site:

http://www.a-eberle.de/pdf/dbsys_gb.pdf

(see table 1)

master/follower - same transformers, same tap change
master/slave - same transformer, same tap change with permanent tap offset

but, why is there a permanent tap offset on the master/slave configuration?

Thanx




RCC

 

[jbartos]

Suggestion: The permanent tap offset accounts for voltage drop between those two transformers, because of voltage drop along the feeder.

 

[jbartos]

Small addition: The permanent offset also cover the voltage drop across the slave transformer.

 

[busbar]

RC—“Tap offset” may be to reduce circulating currents {er, var flow} between the paralleled transformers if they are not identical in electrical characteristics.

 

[busbar]

Also, "tap offset" could be used to force proportionate load sharing in differing size transformers.

 

[jbartos]

Suggestion: Normally, the project engineering or conceptual phase covers power distribution voltage profile diagrams similar to IEEE Std 141-1993 (Red Book) Figure 3-4 Range A Voltage Profile Limits.