Special Control Cicuits Flashcards
3 basic types of timers?
Spring wound
Mechanical/electrical time switches
Timing relays
Spring wound timers can be used for?
Lights
Bathtub spa motors sauna
Mechanical timers
3 things about them
Electrically driven clockwork
Adjustable trip mechanism
Cams
Timing relays
More acurate
Controlled by pneumaticslly air pressure
Or dashpots
Dashpots?
Control the rate gas or liquid flows thru a home between chambers
TDOE are good from ____ seconds to ____ hours
0.05 sec
300 hours
TDOE other names?
On delay
Delay of realase
TDOD other names?
Off Delay
Delay on release
3 timing functions?
Interval
One shot
Repeat cycle
Interval timing changes condition _____ but stay changed for a specified timing period
Immediately
One shot requires
Power to be applied to the relay and to the start terminal of the relay
One shot timing example
Auger to run a set time when a bin fills
TDOE timing relay is first energized what are the conditions of?
NO
NC
NC IC
NO = OPEN
NC = closed
NC IC = open
When TDOD is first energized what condition would be for
NO
NC
NC IC
Open.
Closed
Open
TDOD has timed out what condition of
NO
NC
NO IC
Closed
Open
Closed
TDOD has been deenergized
NO
NC
NO IC
Closed
Open
Open
Why isna timing relay used in a wye Delta?
Slow stsrt up and come up before goes to delta
Brake mechanism is held close or open by spring tension
Held close
Dynamic braking/ magnectic braking
Motor stopped as if it was connected as a generator
Ac braking is called?
Dc injection braking
Done in the stator
Mechanical friction braking solenoid is connected in _____ with motor leads
Parallel
Why are motor breaks used on large ventilation fans?
Prevent going backwards when de energized
Braking that is used in induction motors?
Plugging
Anti plugging used for?
Protect motor from being revered before motor has slowed to near zero
Anti plugging switch NO or NC
NC SWITCH
Control transformer used for 2 reasons?
Safer voltage
Isolate control cct from power cct
What terminals for a electric brake in parallel with a 3 phase motor
T2 t3
Whats required when using anti plugging on a 3phase motor
Anti plugging switch
Normal equip
Anti plugging can be applied to?
3 ohase with anyload?
Single phase
Certain 3 phase motors
Any 3phase with a load
Secondary is usually grounded on a single winding transformer to terminal
X2
When anti plugging is applied to a motor it will ____ to a stop
Coast
