Download Starting Review Starting Review Simple Reduced Current Simple

1/31/2017
Starting Review
Starting Review
Starting at Full Power is called what:
Wait for it….
Starting at Full Power is called what:
“Across The Line” Starting
This can cause inrush currents of how
much?
This can cause inrush currents of how
much?
5-8 times the FLC (Full-Load Rated Current)
Simple Reduced Current
Simple Reduced Current
• Starting at reduced power is called:
• Starting at reduced power is called:
“Soft Start:
• Simplest methods using other Electrical
components:
• Simplest methods using other Electrical
components:
Resistive or Inductive
Reduced Voltage
Reduced Voltage
• Reduced Voltage accomplished through:
• Reduced Voltage accomplished through:
Autotransformer
• This is usually connected in what
configuration?
• This is usually connected in what
configuration?
Open Delta
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3-Phase starting method
3-Phase starting method
• What method reduces starting power by 3
times through how the motor coils are
connected?
• What method reduces starting power by 3
times through how the motor coils are
connected?
Wye-Delta Starting
• 2 Conditions necessary:
1) Must have access to all of the motor
Leads
2) Motor must be designed to allow it
• 2 Conditions necessary:
Transitions
Transitions
• What can happen if the motor runs free for
even a short time while starting?
• What can happen if the motor runs free for
even a short time while starting?
The Rotor can induce high voltages in the
Stator windings that will clash with the
system voltage when it is switched back in.
• How is this problem eliminated?
“Closed Transitioning” in whcich the motor is
never disconnecting the power during
starting
• How is this problem eliminated?
Objectives
CHAPTER 27
Part Winding Starters
• Describe the construction of a motor
designed to be used for a part winding
starter.
• Discuss three step starting for part winding
motors.
• Draw a control circuit for a part winding
starter.
• Connect a motor for a part winding starter.
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Part Winding Starters
The Motor (Contains 2 windings)
• The motor
– Motors designed for part winding starting contain
two sets of stator windings.
– The stator windings and can be either wye or delta
depending on the manufacturer of the motor.
– The windings are designed to be connected in
parallel with each other.
– When the motor is started, only one winding is
connected to the source. After a preset time, both
windings are connected to the source at full
voltage.
Overload Protection
Part Winding Starter Control Circuit
With Overload Protection
• Each winding is protected individually by
means of overload heaters.
• Each set of heaters (three per set) must
be sized at one half the motor
nameplate current.
• The overload contacts from each relay are
connected in series.
Dual Voltage Motors used as PW
• Some, but not all, dual voltage motors may
be used for part winding starting. Contact
motor manufacturer before an attempt is
made.
• If this is possible the motor must be
operated on the low voltage connection.
• Delta connected dual-voltage motors
cannot be used for part winding starting.
Each set of
windings has
OL Heaters
set for ½ rated
Current
Both OL NC
Contacts in
series
Dual Voltage Motors
• Dual voltage
connection
used for part
winding
starting
– This will only
work for WyeConnected
Motors
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Using a Dual V Motor for Part
Winding Start
1) Contact Manufacturer
2) Must be connected for Low Voltage
3) Must be in Y Configuration
Three-step Starting
1) Resistive, Part
Winding start
2) Full Voltage on Part
Winding
3) Full Voltage to Both
Windings
• A Watchdog
Timer (TR2)
disconnects
the motor if
the second
winding
does not
energize.
Motor Application
• Part winding starting typically used for
motors that supply centrifugal pumps,
fans, and blowers
• Often used in commercial air conditioning
and refrigeration applications
• Not for starting heavy inertia loads that
require excessive starting time
Automatic Shutdown
• The part winding motor is very sensitive to
the amount of time the start winding can
be energized without the run winding
becoming energized.
• If the start winding is energized too long
without the run winding, it can become
severely damaged.
• #5, Start pressed,
nothing happens,
no clicks, no
motor bumps…
Where would you
first look for the
problem?
• Note, this is a
“NOT” problem
where three of
the 4 options
COULD be the
problem.
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• #6 Start
Pressed, CR
energizes and
opens after 4
seconds. Motor
never moves. A
failure in what
rungs would
cause this?
• …
• #5, Start pressed, nothing
happens, no clicks, no motor
bumps… Where would you
first look for the problem?
• If Nothing
happens look to
the beginning:
Transformer,
Fuse, First
rung…
• #6 Start Pressed, CR
Summary
energizes and opens after 4
seconds. Motor never
moves. A failure in what
rungs would cause this?
• In this chapter, we discussed:
• CR Energizes
so Rung 1 is
good.
• Motor does
not start, and
M1 causes the
rest of the
sequence so…
– The construction of a motor designed to be
used for a part winding starter
– Three-step starting for part winding motors
– The control circuit for a part winding starter
– How to connect a motor for a part winding
starter
ROLL CALL
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