motortronics MWH Series Installation and operation manual

MOTORTRONICS
TM
Solid State AC Motor Control
INSTALLATION & STARTUP MANUAL
MWH
10 to 80 Amp Models
Heater Controller
Series

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Table of contents
1 General Information ............................................................................................................. 3
1.1 Description..........................................................................................................................3
1.2 Features..............................................................................................................................3
1.3 Specifications......................................................................................................................4
1.4 Receiving and Unpacking....................................................................................................4
1.5 Dimensions .........................................................................................................................4
2 Installation........................................................................................................................... 5
2.1 Wiring..................................................................................................................................5
3 Operation.............................................................................................................................. 8
4 Diagrams..............................................................................................................................9
4.1 MWH 10 Amp Model............................................................................................................9
4.2 MWH 25 Amp Model.......................................................................................................... 10
4.3 MWH 50 Amp Model.......................................................................................................... 11
4.4 MWH 80 Amp Model.......................................................................................................... 12
WARRANTY INFORMATION ......................................................................................13

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Chapter 1 - General Information
1.1 Description
The Motortronics MWH Series Solid State Motor Winding Heater is designed to prevent condensation build-up by
applying a low level current to the AC motor windings when the motor is in the “off” condition. Motor windings are
susceptible to condensationformation each timethemotor isstopped andthewindings’temperaturedropsbelow
thedew point.Overaperiod of timethiscondensationbuild- up can degrade the insulation of the windings and
cause a short circuit when the motor isstarted. The same problem can occur when motors are not operatedfor an
extended period of time. This isespecially true for damp and humid locations.
1.2 Features
Fully Automatic Operation
The Motortronics MWH Series is designed for fully automatic operation. It turns on approximately one minute after
it receives power. When themotorisstartedtheMWHisinstantly turned off. The MWH turns back on
approximately one minute after the motor is turned off.
Overload Sensing
With the optional overload sensing, the MWH can be disabled automatically when a motor overload trip occurs.
The heater will go back on-line automatically after the overload is reset. This prevents additional motor heating
when a trip occurs providingfaster motor cool down after a thermal overload trip condition.
LED Status Display
Indicator lights on the MWH inform the operator of theunitstatus.ThePOWERON indicator shows that the power
is on and both of the MWH fuses are good. The ENABLE indicator shows that themotor is off and the MWH
control interlock is closed. The OUTPUT ONindicator showsthat the MWH issupplying power to the motor
windings.
Designed for Safety
The MWH Series is supplied in a compact open chassis design. Optional NEMA 1 enclosures are also available.
The front cover of the unit is fiber- glass insulationmaterial which shields against accidental contact with electrically
liveparts.

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1.3 Specifications
MODEL
MAX AMP
RATING
MOTOR HORSEPOWER RANGE
208V
240V
480V
575V
MWH-10
10
3 - 40
5 - 50
10 - 100
15 - 125
MWH-25
25
50 - 100
60 - 125
125 - 250
150 - 300
MWH-50
50
125 - 200
150 - 250
300 - 500
350 - 600
MWH-80
80
250 - 300
300 - 400
600 - 800
700 –900
Table 1
Adjustments: Output voltage is factory set to provide sufficient power to the motor to maintain a +5° to 10°C
differential above ambient temperature which is suitable for most applications. This adjustment can be used totrim
the control as requiredfor eachapplication.
Fusing: Two fuses protect the MWH.
Transient Protection: An RC snubber circuit across the SCR protects it from rapid rate of change in the system
voltage. A metal oxide varistor (MOV) protects the unit against voltage spikes on the line.
1.4 Receiving and Unpacking
Unpacking - Carefully unpack the unit from the shipping carton and inspect it for shipping damages. Immediately
report any damagestothecarrier.
Mounting - Select mounting location and make sure ambient temperature does not exceed operating range limits
given in specifications. Allow for sufficient clearance on all sides of the unit.
1.5 Dimensions
Dimensions are in inches.
MODEL
OPEN PANEL
NEMA1 (N)
H
W
D
H
W
D
MWH-10
6.2
4.5
6
11
7
7
MWH-25
8
6
6
11
7
7
MWH-50
10
8
7.9
15
10
8
MWH-80
10
8
8
20
10
10
Table 2

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2.0 - Installation
2.1 Wiring
Connectiondiagramsillustratetypical wiringconnections. Use 75° C minimum wires.
Note: All wiring must comply with local codes, regulations and ordinances.
WARNING!
Do not service equipment with voltage applied. Unitcan be thesourceof fatal electrical shocks.
1. Mount the MWH on avertical panel with the line connection (L1, L2) at the top. Proper orientation is requiredto
achieve proper convention cooling of the solid state power device (SCR).
2. Remove the front cover of the winding heater for access to the power and control connections.
3. Recommended fuse and power wire sizes for MWH:
Table 3
Table 4
MAXIMUM
MWH AMP
WIRE SIZE TYPE
AWG
REPLACEMENT FUSE
F1
F2
10
14
Class T 600V 15 A
Class CC 20A Time Delay
25
8
Class T 600V 30 A
Class T 600V 70A
50
6
Class T 600V 60 A
Class T 600V 100A
80
2
Class T 600V 100 A
Class T 600V 150A
TORQUE LB/IN
MWH
L1
L2
T1
T2
10
20
20
45
20
25
20
50
50
50
50
20
50
50
50
80
50
50
50
50

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4. Connect L1 and L2 on the MWH to L1 and L2 on the magnetic contactor usingthewiresizerecommended
foryour unit.(Seetable 3).
5. Connect T1 and T2 to the load side of themagnetic contactor before the over loadrelayheaterelements as
shown below. Do not connecttothe output terminals of the overload relay. Use the wire size recommended
for your unit.
6. If your system utilizes a heater off-on switch,connectitinserieswithnormally closed auxiliary contact on the
motor starter to the terminals labeled “SW”. Use AWG 16 wire for the circuit.
7. If your system does not utilize a heater off-on switch, connect the normally closed auxiliary contact directly to
the terminals labeled “SW” (TB1). Note: The cover of the motor winding heater depicts the connection
diagram (See wiring diagrams below).
8. If required, connect the normally open contact from the motor overload to the overload connection as shown
on the wiring diagram.
9. Replacethecoverwhenallconnections have been completed and checked.
Wiring Diagram for units rated at Wiring Diagram for units rated at 25 Amps
10, 50 and 80 Amps

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10. Included with each unit are two self-adhesive warning labels. Attach one warning label in a conspicuous place
on the motor junction box and the other on the outside of the starter enclosure.
WARNING
THIS MOTOR IS EQUIPPED WITH A MOTOR
WINDING HEATER. VOLTAGE IS PRESENT AT
MOTOR TERMINALS EVEN WHEN
MOTOR STARTER IS OPEN. BEFORE
SERVICING MOTOR OR MOTOR WIRING
ALWAYS DISCONNECT MAIN POWER AHEAD
OF MOTOR STARTER.
Sample Warning Label
11. If themotor winding heater is to be paralleled with asoft start, thecustomer must provide anisolation contactor
between the output of the MWH and the motor as shown in the figure below.
Wiring Diagram for units rated at 25 Amps

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3.0 - Operation
1. Apply line voltage to the system. The “Power On” LED on the MWH should light. If the “Power On” LED does not
light, it is an indication of a blown fuse or improper connections. Do not proceed until this is corrected.
2. If the motor starter is off and the “SW” circuit is closed, then the “Enable On” LED will be on. The MWH will turn on
automatically in approximately 1 minute.
3. The “Output On” LED will turn on when the MWH begins to apply voltage to the motor.
4. The output voltage to the motor is factory set for 8% to 9% of the line voltage. (Measured with an RMS AC
Voltmeter) Maximum range of this adjustment is approximately 15% of line voltage.
Note: Caution must be used when adjusting the output. Too high a setting may cause excessive heating in the motor.
5. During initial start-up monitor the output current to the motor. Use a DC clamp-on ammeter. Output current must not
exceed the rating of the motor winding heater unit.
6. When the motor is starting the MWH automatically shuts off. It will remain off until the motor is turned off. The MWH
will then turn on after approximately1 minute.
LED Placement

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4.0 - Diagrams
4.1 MWH 10A Model

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4.2 MWH 25A Model