User`s guide

Appendix A - Logic Application Examples
Motor Starters with Permissives Example
230 UMC800 Control Builder User’s Guide Release E
1/01
Motor Starters with Permissives Example
Motor Starters with Permissives - Relay Logic Conversion
This relay logic is part of a
furnace startup involving a
series of motor starters. Each
starter switch 1M thru 5M must
be confirmed closed for
continued operation and latch-
in after the Start switch is
pressed. The Stop switch is
again shown normally closed.
Internal motor overload
contacts are in series with the
starter switches, any one of
which will cause shutdown or
prevent startup.
Internal motor
overload contacts
Motor Starters with Permissives - UMC 800 Logic
This is the conversion
from the relay ladder
logic (the internal
motor overload
contacts are assumed
to be wired in series at
the motor, then to the
starter switches). The
multiple AND for the
motor starter switch
permissives, (IM, 2M,
4M, 5M) converted
first, with that output
ORed with the Start
pusbutton switch,
which is ANDed with
the Stop pushbutton.
The Stop pushbutton
is wired as normally
closed (push to
opencircuit), therefore,
is not negated. All
outputs to the motors
can be connected in
common to the AND9
output.
14 function blocks