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AT120A, AT140A, AT150A, AT175A UNIVERSAL TRANSFORMERS
Mounting Through Outlet Box Knockout
The transformer can be mounted on an outlet box using
the clamp on the primary end bell. The mounting plate is
not used. To mount the transformer on an outlet box:
1. Turn the clamp screw almost all the way out.
2. From outside box, thread the primary leadwires
through suitable 7/8 in. knockout. Fit the clamp and
screw through the knockout. Do not mount the
transformer through a plastic knockout.
3. Tighten the clamp screw securely against the rim
of the knockout. Avoid damaging the leadwires
with the screwdriver.
WIRING
All wiring must comply with local codes and ordinances.
Disconnect power before making wiring connections to
prevent electrical shock or equipment damage.
1. Make primary connections to the line voltage
power supply. On multitap models, be sure to use
correct leads for available power supply. See
Fig. 6.
2. On multitap models, insulate the ends of the
unused leads using wire nuts or capping with a
solderless connector.
3. Make secondary connections to 24 Vac control
circuit.
CHECKOUT
CAUTION
Voltage Check Hazard.
Overload current protection is inherent on
AT120, AT140, and AT150. A fused 3.5 Amp
secondary is used on AT175.
Do not short transformer secondary terminals.
Voltage Check
After installation is complete, turn on power supply and
perform a voltage check:
1. Place controlled equipment in operation and
observe through one complete cycle.
2. Using a voltmeter, check for proper primary and
secondary voltages.
3. If voltage readings are incorrect, be sure primary
voltage connections are made correctly.
4. Measure voltage again:
a. If correct primary voltage is measured and
secondary voltage is significantly less than the
voltage shown on the regulation curves,
transformer winding is damaged. Replace
transformer and repeat checkout procedures.
b. If primary voltage is 0V, be sure power supply
is connected correctly or repair, if necessary.
Repeat checkout procedures.
Automation and Control Solutions
Honeywell International Inc.
1985 Douglas Drive North
Golden Valley, MN 55422
customer.honeywell.com
® U.S. Registered Trademark
© 2005 Honeywell International Inc.
69-0251-3
G.H. Rev. 06-05
Honeywell Limited-Honeywell Limitée
35 Dynamic Drive
Scarborough, Ontario M1V 4Z9
5. Do not put system into operation unless correct
primary and secondary voltages are measured.
SINGLE VOLTAGE MODELS
COMMON
VOLTAGE
PRIMARY
VARIES
WITH MODEL
3
120 V - WHITE
208 V - RED
240 V - ORANGE
277 V - BROWN
480 V - BLACK/RED
120/240 MODELS
COMMON
BLACK
120 V
PRIMARY
WHITE
3
240 V
ORANGE
208/240 VAC MODELS
COMMON
208 V
PRIMARY
240 V
3
120/208/240 VAC MODELS
COMMON
120 V
PRIMARY
208 V
3
240 V
1
SECONDARY CONNECTIONS ARE SCREW TERMINALS, 1/4 INCH
QUICK-CONNECTS OR BLUE AND YELLOW LEADWIRES.
2
BLACK IS COMMON WITH RESPECT TO THE TRANSFORMER
WINDING ONLY AND NOT THE EXTERNAL CIRCUIT.
3
SOME MODELS AVAILABLE WITH 1/4 INCH QUICK CONNECTS.
Fig. 6. Schematics for single and multitap
transformers.
By using this Honeywell literature, you agree that
Honeywell will have no liability for any damages arising out
of your use or modification to, the literature. You will
defend and indemnify Honeywell, its affiliates and
subsidiaries, from and against any liability, cost, or
damages, including attorneys' fees, arising out of, or
resulting from, any modification to the literature by you.
2
BLACK
SECONDARY
1
2
SECONDARY
1
2
BLACK
SECONDARY
1
RED
ORANGE
2
BLACK
SECONDARY
WHITE
1
RED
ORANGE
M22974
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