Salmon Egg said:
It is not clear to me that the OP still knows anything about his
equipment in a serious way. I do not even know if he understands that he
has to run with negative slip.
I do remember a machinery exercise in school over 50 years ago. I was in
a group of three or four students working together. I more or less knew
what I was doing. I think we were assigned synchronization of a
alternator. I do not remember for sure whether synchronization was to
the line or to another alternator. I think that it was two alternators
because I remember we had to work furiously at it in order to finish the
tests.
At least one alternator was driven by a dc motor. We got near
synchronous speed. We checked out phase sequences, voltage difference
etc. We were using three incandescent lamps to indicate when it was time
to connect our alternator. Everything went well but we almost ran out of
time during this three hour lab.
Meanwhile, the group next to us was having nothing but trouble. Maybe,
they were finally getting ready to throw the big switch, Having
completed our tasks, I was going to try something else while the
equipment was up and running. I do not remember what it was. Whatever it
was, I ended up tripping some circuit breakers that shut the other guys
down. I do not remember if I had some schadenfreude from that incident.
Bill
It's easy to synchronize a lab machine to the system and then to adjust
loads. In that case the lab machine isn't going to measurably affect either
the voltage or the frequency. It is also easy to synchronize one small
machine to another, both driven by DC motors, Hold one steady and match the
other in voltage and phase using lights. The fun that occurs next (and
appears to be what you had) is load sharing (say with even a resistance
load) and voltage control. If the people running the two units are both
trying to control frequency and load as well as voltage and var sharing- you
have two cats fighting in a bag. If one machine deals with load sharing and
the other with voltage , it is somewhat easier but still a balancing act.
It is also possible to pull a machine out of synch (under exciting can do
it) in such a lab situations - so hit the breaker now or make a quick
correction before any damage is done -those machines (if they were similar
to what I used in class - typically about 5HP units -often Westinghouse, did
have pretty good damper windings which helped.
The "White and Woodson" universal machines, made by Westinghouse, which
came out in the 50's for lab use could be configured as DC, or AC machines
of any flavour- which was nice but they weren't typical in any mode of
operation- one size doesn't fit all -but they did illustrate the principles
in the White and Wilson text..
--
Don Kelly
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Your heirs might not think so!
If you have no heirs, then there is merit (?) in blowing it all and going
into debt.
