Motor Connections

[an error occurred while processing this directive] Motor Connections
I've listed how to hook up the motor leads on both Single and 3 phase

motors.

Motors Menu, Select an Item
Formulas	Controls	LV 1 Phase	LV 3 Phase Wye
Low Voltage Coil	3 Wire Control	LV 1 Phase Mag Starter	HV 3 Phase Wye
High Voltage Coil	3 Wire w/dual S/S	HV 1 Phase	LV 3 Phase Delta
	2 Wire Control	HV 1 Phase Mag Starter	HV 3 Phase Delta
	2 Wire w/HOA		3 Phase Mag Starter

F - Frequency - AC cycles per second, listed as Hertz (Hz), Cycle (Cyc), or Frequency (Freq.)

Most are either 60Hz (United States), 50Hz (Overseas), or may be both.

NP - Number of Poles - The number of poles per phase. 2 are required, must be an even number.

Think of a magnet, it has 2 poles (N and S), 2 magnets have 4 poles, etc.

Rs - Rotor Speed - Rotor speed as shown on data plate or as obtained by a tachometer
RPM - Revolutions Per Minute (RPM) - Speed of rotor.

May have 2 listings on data plate if a dual frequency motor. Slower is 50Hz, Faster is 60Hz.

Ss - Synchronous Speed - Speed of Rotating Magnetic Feild (RMF) within stator. In RPM's

Determined by number of poles and frequency of power supply.

Slip - Rotor Slip - Difference between Ss and Rs. Normally 2-5%

As slip increases, torque increases until a breaking point where motor
either stalls or locks up. usually created by a mechanical overload. 25% for induction type.

Formulas:
Synchronous Speed (Ss)

Ss=(2*Hz)(F/NP)

If 60Hz and 4 poles; Ss=(2*60)(60/4)=(120)(15)=1800
Synchronous Speed is 1800RPM

Slip

Slip=Ss-Rs

If rotor speed is 1728; Slip=1800-1728=72
Slip is 72RPM

Slip Percentage

slip%=(Slip/Ss)*100

if Slip=72; slip%=(72/1800)*100=0.04*100=4
Slip Percentage is 4%

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Control Connections
If you are using a Magnetic Starter, you will need something to control the coil.
The purpose of a Magnetic Starter is to reduce the load on the switching means.
This means you can control a high current motor (say 20A, 3

, HV) with a control that can't handle the amperage (say a 15A, 120V, single pole switch).
These mag starters may also be used to remotly switch large current draw loads such as HID street/parking lot lighting with a single switch/photocell.

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Low Voltage Coil Connections
This is how you will connect a Low Voltage (110-130V) Coil
One side will be to phase, the other to neutral.
Probably only used on 1

, low voltage motors.

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High Voltage Coil Connections
This would you would connect a High Voltage (210-230V) Coil
Both sides go to a phase
Most common, used on everything except 1

, low voltage motors.

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Manual Start/Stop Station Diagram
This is a Manual (3-wire) Start/Stop Station connected to a mag starter.
This shows the newer style S/S Station, just match the numbers on older stations.
The start button is normally open (N/O), stop normally closed (N/C), with stop in series with holding contact.

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Dual Start/Stop Station Diagram
This is how to connect 2 S/S Stations to a single mag starter.
The start buttons are in parallel, stop buttons in series (for safety).
If you press the stop button on either station (even with either start depressed) The mag starter will disengage, turning off the load.
Want more? Add more like shown (start in parallel; stop in series).

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Automatic Control Diagram
This is how you will connect an automatic (2-wire) means to the mag starter.
It could be a float switch, thermostat, non-momentary contact switch, etc.
A thermostat is shown here, with the mag starter hooked to the "cool" terminal.

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Automatic with HOA Switch
Here is the Automatic (2-wire) control going through the HOA switch
The HOA (Hand-Off-Automatic) switch is useful for troubleshooting/maintainance.
In the Hand position, it powers the coil directly, useful for troubleshooting.
In the Auto position, it sends power to the automatic control to allow it to funtion.
In the Off position, it does not allow coil to be energized, useful for maintainance.

phase, low voltage (parallel) diagram.
This will be for 1

motors with a voltage rating of between 110-130V

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Low Voltage, Single Phase Magnetic Starter
This is how you would hook up a magnetic starter ("mag starter") to a LV single phase motor

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Single Phase, High Voltage
This is a high voltage (series), single phase.
Will be for motors with rating of between 210-230V

config.

All this was done in Windows

, yay!
Email me at kaneo666@yahoo.com if you would like to use these pictures, thanks.
Last Modified: Monday, 16-Aug-2004 18:25:22 EDT.
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