As the title emplies, I know just enough about this... but was hoping
to get some backup before I place some current to this project.
Here's the background for the project:
An AC drive unit
is being controlled by a radio remote.
The drive has both fwd and rev functions that have to remain latched
to operate. I'm wanting to setup two functions on the transmitter of
the remote: one fwd, one for rev. But one function needs to be turned
off, when the other one is operating, and visa versa.
I'm thinking a simple, single coil latching relay will accomplish
this, but I've never worked with one so here is where I'm in need of
Looking at the wire diagram of this relay
should there be a constant 12vdc current on the coil, and the switches
operated with simple open and closed "dry" circuits? (if 9 and 6 are
closed, 7 and 4 will close?).
More background, the remote signal can either be momentary or
One way would be to use a polarized relay that stays on whichever
side it was last driven to. The coil needs a positive or a negative
DC pulse to switch it over and then it will remain ther until it
receives the opposite pulse.
If you can send two different momentary radio frequencies for
"forward" or "reverse", they can be decoded simply as a positive or
negative DC pulse to the polarized relay.
and 6 are
a latching relay only takes momentary power to close and latch
in that position... then depending on the relay, a second
momentary powering unlatches the relay and it opens.
Thus the term latching relay
non latching relays require constant power to operate the
First; responses to my original question are greatly appreciated.
I've been rushing around trying to finish up this year's harvest and
have not had the time to properly acknowledge the help.
The first two responses clued me in on how a relay like this would
work. A momentary dc voltage applied to the coil(s) will switch
circuits like I wanted (open one, while closing the other and visa
versa). Using a dual coil allowed me to use a separate switch to
reset the circuits to their original state.
Mod, I'm not following your suggestion... the controls I'm dealing
with seem to be 'happy' with a dc system, which was also readily
available as an output from the ac drive. Is there an advantage to
using ac over dc for controlling relays?
One more question, if I may. I've got the unit functioning as
intended... here's the wiring diagram:
plus the layout of the relay:
My concern is with switching on the common side of the system (a- and
5-). Like I said, it's working, but is there any problem with
continuous hot leads to the relay (B+ and 8+). Originally I was
switching the positive side, but I had separate common terminals on
the receiver. That option is not available on this new, better
Any other problems with this layout that a relative novice like me
might be missing?
Also, a question about torque settings on an ac drive:
Is it posssible to have the torque boost setting too high? Can it
cause damage to the motor?
Bumping up this setting was necessary to have the motor start with
decreased acceleration setting. My particular pump has trouble
reversing due to the substantial amount of resistance, and I'm curious
if higher torque boost could do the trick... without burning up
something. Any references where I can bone up on torque applications?
thanx again for previous and future help,