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Old automatic gate controller question.

D

David Farber

Jan 1, 1970
0
Ross Herbert said:
Yipes! All those uninsulated terminals look dangerous to me....

Drawing out schematics of relay equipment is an art in itself. You
have to establish conventions (ie, moving and stationary contact sets,
coil relationships and status of the total mechanism). You must draw
the whole system when it is in a defined state, such as "gate closed",
and then draw the state of each relay and its associated contacts in
this condition, remembering that the moving and stationary contact
springs must also be drawn to reflect the associated relay situation.

For example your notes say that Relay A is shown de-activated but the
schematic is drawn such that its coil IS activated via the limit close
switch (ie. the gate is closed). Also, the schematic shows the timer
relay is activated from GND at C/9-3 (deactivated) via A/8-3
(deactivated) to 24Vac, yet the timer relay contact is shown as being
open.

The schematic also shows the main power switch is ON and the B relay
is activated. I assume those B contacts are supposed to be normally
open when the relay is deactivated, so if this assumption is correct
and the relay is drawn in its activated position, then the contacts
should be drawn with the moving contact at the top being pulled
towards the coil and making contact with the stationary contact. As
drawn the contacts are shown as opening when the coil is activated but
I assume you meant to draw it with the contacts making when the coil
is activated.

Also, where is the motor connected and what voltage supply powers the
motor?

Unless you can clearly define the status and show things as they
really are in that condition, then it is difficult to work out how
things are meant to work.

Having said that, your first effort is to be commended, considering
you probably haven't had to do this sort of thing before.

I haven't had to do this thing before. I don't envy the people that have to
do this either.

I had another look at the box last night. I removed the three relays from
their mounting plate to see if I could isolate the chattering. It turned out
the relay which I thought was always on, relay b in the schematic, is not
always on. It's only on when the gate is stationary. I've revised the
schematic, http://www.pbase.com/image/81318340 and also used your advice to
make the descriptions at the top of the schematic actually match what is
shown.

The motor is driven by 240VAC which does not enter the controller part of
the gate. However I did notice that whatever is switching relay b on and
off, is coming from one of the four wires (not shown) coming from the motor.
Eventually I'll have to figure that into the drawing as well.

The question now is what is the circuit path that keeps the closing
coil/solenoid energized once the gate starts to close and relay b is turned
off? I have certainly missed something in translating the actually wiring to
the schematic drawing.

Thanks for your reply.
 
D

David Farber

Jan 1, 1970
0
m kinsler said:
AC,

You've got a bad pair of contacts feeding the coil of one of the
relays. The chattering relay is probably not the one that is at
fault; the difficulty might well lie in that sensor switch. I've had
difficulties with magnetic reed switches in the past, and if there's
one there I would see about it. There may also be a bad connector
associated with the sensor switch. Find the wires that go to the
sensor switch and use a jumper across them to simulate the operation
of that switch. If the relays operate but do not chatter, then the
difficulty lies in the sensor switch or its wiring.

M Kinsler

Now that I've added the motor circuits to the schematic, you will notice
that the coil in the B relay is in series with what looks suspiciously like
a motor start capacitor. Can this be correct?

http://www.pbase.com/image/81471200

Thanks for your reply.
 
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