Honeywell AT140A, AT175A, AT150A, AT120A User Manual
AT120A, AT140A, AT150A, AT175A
Universal Transformers
INSTALLATION INSTRUCTIONS
APPLICATION
These transformers are for use in 24 Vac nominal control
circuits. They are typically used in heating/cooling control
systems but can be used in any application that does not
exceed the load ratings. They meet National Electrical
Table 1. Model Specifications.
Primary Secondary
Model
Number
AT120A 120/208/
AT140A 120 9 in. leads 27.0 24.0 Screw
AT150A 120/208/
AT175A 120/208/
Input
Vol tag e
(60 Hz)
240
120/208/
240
120/240
208/240
240
240
Wiring
Connections
9 in. leads 27.0 24.0 Screw
9 in. leads 27.5 24.0 Screw
9 in. leads 27.5 24.0 Screw
Open
Circuit
Code Class 2 “not wet” and Class 3 “wet” requirements
and are Underwriters Laboratories (UL) Inc. listed under
UL 1585. They can be mounted through a 7/8 in. knockout on the accessory mounting plate (included), or with
the integral mounting feet. See Table 1 for additional
specifications.
Vol tag e
At Rated
Power
Output
Wiring
connections
terminals
terminals
terminals
terminals
Output Rating at
100 Percent Power
20 VA
40 VA
50 VA
75 VA
Factor
INSTALLATION
When Installing this Product …
1. Read these instructions carefully. Failure to follow
them could damage the product or cause a hazardous condition.
2. Check the ratings given in the instructions and on
the product to make sure the product is suitable for
your application.
3. Installer must be a trained, experienced service
technician.
4. After installation is complete, check out product
operation as provided in these instructions.
CAUTION
Electrical Hazard.
Can cause electrical shock or equipment
damage.
Disconnect power supply before beginning
installation.
69-0251-3
AT120A, AT140A, AT150A, AT175A UNIVERSAL TRANSFORMERS
Mounting
The transformer can be mounted in one of three ways:
— foot mounting.
— plate mounting.
— mounting through outlet box knockout hole.
Foot Mounting
1. Mount the transformer using screws (not supplied)
through the four 3/16 in. x 3/8 in. holes in the
mounting feet.
2. Make line voltage primary connections within an
approved enclosure. See Fig. 1.
3. Discard the mounting plate.
USE SCREWS OR
BOLTS THROUGH
SLOTS (4) IN
MOUNTING FEET
LEADWIRES
FOR PRIMARY
CONNECTIONS
SCREW TERMINALS
FOR SECONDARY
CONNECTIONS
LEADWIRES
FOR PRIMARY
CONNECTIONS
CLAMP SCREW
AND CLAMP
LEADWIRES
FOR PRIMARY
CONNECTIONS
PLATE MOUNTED AT CLAMP ON PRIMARY END BELL
MOUNTING PLATE
SCREW
END
BELL
RAISED PORTION OF
LARGE CENTER KNOCKOUT
TERMINALS FOR
SECONDARY
CONNECTIONS
PLATE MOUNTED AT THE LAMINATIONS
MOUNTING
PLATE
MOUNTING
SCREW
SCREW
TERMINALS FOR
SECONDARY
CONNECTIONS
1
MOUNTING
FOOT (2)
M9161
Fig. 1. Foot mounting.
Plate Mounting
MOUNTING PLATE TO TRANSFORMER
Mount the plate to the transformer in either of two
positions (see Fig. 2):
• at clamp on primary end bell.
• at laminations.
69-0251-3 2
1
1
MOUNTING FEET ON "A" MODELS ONLY.
Fig. 2. Mounting plate to transformer in either
of two positions.
MOUNTING PLATE AT CLAMP ON PRIMARY END BELL
1. Turn the screw on the clamp almost all the way out.
2. Hold the mounting plate with the keyhole slots up
and the raised portion of the large center knockout
away from you.
3. From the back, thread the primary leadwires
through the round center hole in the plate.
4. Fit the clamp and screw through the round hole.
5. While holding the plate in place, tighten the
setscrew securely against the rim of the hole.
See Fig. 3. Avoid damaging the leadwires with the
screwdriver.
M9162
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