resideo AT120A-E Transformer Owner’s Manual

resideo AT120A-E Transformer

PRODUCT DATA

FEATURES

• AT120 is rated at 20 VA.
• AT140 is rated at 40 VA.
• A Tl 50 is rated at 50 VA.
• AT160 is rated at 60 VA.
• AT175 is rated at 75 VA.
• All models meet National Electrical Code Class 2 not wet, Class 3 wet transformer requirements.
• All models conform to Underwriters Laboratories Inc. Standard UL 1585.
• Color-coded leadwires for primary connections and screw terminals for secondary connections, fixed 1/4 inch (6 mm) male quick-connects or color-coded leadwires for both primary and secondary, are standard.
• Models available with stripped leadwires, leadwires with variety of terminals, or special terminations as required on both primary and secondary.
• Mounting options include clamp mounting on outlet box knockout, plate mounting, foot mounting, panel mounting, conduit/panel and a combination.
• Models available for 120V, 240V, 277V, 480V, 120/240V, 208/240V,277/480V, 120/208/240V,208/240/480V,or 208/277/480V supply at 60 Hz.
• ”F” models include a button for manually resetting the circuit breaker.

APPLICATION
These general purpose transformers provide power to 24 Vac circuits. They are typically used in heating/cooling control systems, but can be used in any application that doesn’t exceed the load ratings.

SPECIFICATIONS

IMPORTANT The specifications given in this publication do not include normal manufacturing tolerances. Therefore, a sample unit may not match the listed specifica­tions exactly. A/so, this product is built and tested under closely controlled conditions, and some minor differences in performance can be expected if those conditions are changed.

Models: A Tl 20A-E; A Tl 40A-E; A Tl 50A,B,D-F; A Tl 60B; ATl 75A-D,F.
Electrical Ratings: See Table 1.

Model Number

| Output Rating at

100 Percent Power

Factor”

| ****

Primary Input Voltage (60 Hz)

| Secondary Output Voltage
---|---|---|---
Open Circuit| At Rated Power Output
AT120| 20VA| 120, 240, 277, 480, 120/240,

208/240,240/277,277/480,

120/208/240, 208/240/480, or 208/277/ 480V

| 27.0| 24.0
AT140| 40VA|  |
AT150| SOVA| 27.5b|
AT160| 60VA|  |
AT175| 75VA|  |

• Refer to regulation curves.
• Voltage is 27.0V on ATl 50F and ATl 75F models.

Wiring Connections:
“A”, “C”, and “D” models: Primary-9 inch (230 mm) leadwires; Secondary-screw terminals. “B” and “E” models: Primary-9 inch (230 mm) leadwires or fixed 1/4 inch (6 mm) quick-connects. Different length leadwires and leadwires with stripped ends or with termi­nals attached also available. Specify when ordering.
Secondary-9 inch (230 mm) leadwires or fixed 1/4 inch (6 mm) quick-connects. Different length leadwires, leadwires with stripped ends or with terminals attached, and screw terminals also available. Specify when ordering.
“F” models: Primary and Secondary-9 inch (230 mm) lead­ wires.

Mounting Means:

Model Suffix Letter|

Mounting Means

---|---
A| Includes clamp for outlet box knockout, 4 x 4 inch mounting plate for 2 x 4 inch or 4 x 4 inch outlet box, and

mounting feet for surface mount.

B| Foot-mounted.
C| Includes clamp for outlet box knockout.
D| Integral 4 x 4 inch mounting plate fits 2 x 4 inch or 4 x 4 inch outlet box.
E| Panel mounted with two No. 8 screws (not included).
F| Includes l /2-14 NPSM conduit connector and lock nut for mounting on plate or panel (not included) with 7/8 in. knockout, and mounting feet for surface mount.

Dimensions: See Fig. 1 through 5.
Regulation:
See transformer regulation curves, Fig. 6 through 10.

Overcurrent Protection:
Inherent on ATl 20, ATl 40, and ATl 50. Thermal fusible link on ATl 60 and ATl 75. Circuit breaker on ATl 50F and ATl 75F models.

Approvals:
UNDERWRITERS LABORATORIES INC. LISTED (“A”, “C” and “F” models): File No. E14881, Guide No. XOKV.
UNDERWRITERS LABORATORIES INC. COMPONENT RECOG­ NIZED (“B,” “D,” “E” models): File No. El 4881, Guide No. XOKV2.
All models conform to Underwriters Laboratories Inc. Standard UL 1585.
NATIONAL ELECTRICAL CODE: Class 2 not wet, Class 3 wet.

Optional Specifications:

End bells or caps on “B” through “E” models.
Terminations on “B” through “E” models.
Circuit breaker reset button on “F” models.

National Electrical Code: Class 2 not wet, Class 3 wet

A T120A-E; A T140A-E; A T150A,B,D-F; A T160B; A T175A-D,F TRANSFORMERS

A T120A-E; A T140A-E; A T150A,B,D-F; A T160B; A T175A-D,F TRANSFORMERS

A T120A-E; A T140A-E; A T1S0A,B,D-F;AT160B; A T175A-D,F TRANSFORMERS

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 system opera­tion as suggested in these instructions.

CAUTION Disconnect power supply before beginning installation to prevent electrical shock or equipment damage.

Foot Mounting (“A”, “B”, and “F” Models Only)
Mount using screws (not supplied) through the two (“B” models) or four (“A”, “F” models) holes in the mounting feet. Refer to Fig. 11. Line voltage primary connections must be made within an approved electrical enclosure. Discard the mounting plate (“A” models only).
Plate Mounting (Refer to Fig. 12) (“A” and “D” models only) Mounting Plate to Transformer (“A” models only) Mount the plate to the transformer either:

• at the clamp on the primary end ball…OR. ..
• at the laminations.

PLATE MOUNTED AT CLAMP ON PRIMARY END BELL

To Mount Plate at Primary End Bell:

1. Turn the screw on the clamp almost completely 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. Refer to Fig. 13. Avoid damaging the leadwires with the screwdriver.

WITH RAISED PORTION OF KNOCKOUTS FACING YOU:

To Mount Plate at Laminations:

1. Remove the large rectangular knockout in the mounting plate as shown in Fig. 14.
2. Hold the transformer with the clamp on the end bell fac­ing you.
3. With the keyhole slots up, fit the mounting plate over the primary leadwires and the end bell. Insert the small tab at the bottom of the plate into the slot in the transformer mounting foot.
4. Insert the mounting screw (provided) through the holes as shown in Fig. 15. Secure the plate to the transformer, but do not overtighten the screw.

Mounting Transformer and Plate on Outlet Box
The mounting plate may be mounted on 4 inch square boxes, 2 x 4 inch rectangular boxes, and on 4 inch octagonal boxes.

1. Line up the plate with the box to determine the proper mounting holes. The mounting feet and secondary ter­minals will be outside the box.
2. Remove the mounting hole knockouts if necessary.
3. Mount the plate on the outlet box using two screws (obtain locally).

Mounting Through Outlet Box Knockout
(“A” and “C” Models Only)
The transformer can be mounted on an outlet box using the clamp on the primary end bell. The mounting plate (“A” models only) is not used. To mount the transformer on an outlet box:

1. Turn the clamp screw almost completely out.
2. From outside box, thread the primary leadwires through suitable 7 /8 inch knockout. Fit the clamp and screw through the knockout.
3. Tighten the clamp screw securely against the rim of the knockout. Avoid damaging the leadwires with the screwdriver.

Panel Mounting (“E” Models Only)
“E” model transformers are designed for mounting inside a panel using No. 8 screws and washers (obtain locally) through at least two of the four holes in the laminations. Refer to Fig. 16.

Conduit/Panel Mounting

Mount the transformer on a plate or panel (not included) with a 7 /8 in. knockout. The transformer has a 1 /2-14 NPSM conduit connector and lock nut.
NOTE: To meet UL requirements, mount the transformer on a plate or panel with a maximum thickness of 0.15 in. This allows three and one-half threads of the conduit spud to be exposed after the transformer is mounted.

1. With the conduit connector side of the transformer fac­ing the plate, thread the leadwires through the plate knockout.
2. Insert the connector in the knockout.
3. While holding the plate in place, assemble and tighten the lock nut to fasten the transformer securely. See Fig. 17. Avoid damaging the leadwires with the screw­driver.
4. Make line voltage primary connections within an approved enclosure.

SINGLE VOLTAGE MODELS

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, make sure to use the cor­rect leads or terminals for the available power supply. Refer to Fig. 18.
2. On multitap models with leadwires, insulate the ends of the unused leads by taping or capping with a solderless connector.
3. Make secondary connections to 24 Vac control circuit.

Caution Do not short transformer secondary terminals. Overload current protection inherent on ATl 20, ATl 40, and ATl 50. 3.5 Amp fuse available on ATl 60B and AT175A-D.

Voltage Check
After installation is complete, turn on power supply and perform a voltage check.

1. Place the controlled equipment in operation and observe through one complete cycle.
2. Using a voltmeter, verify proper primary and secondary voltages.
3. If voltage readings are incorrect, ensure primary volt­age connections are made properly (refer to Fig. 18).
4. Measure voltage again.
5. If proper primary voltage is measured and second­ary voltage is significantly less than the voltage shown on the regulation curves, transformer wind­ing is damaged.
6. Replace transformer and repeat checkout procedures.
7. If primary voltage is OV, make sure power supply is connected properly or repair if necessary. Repeat checkout procedures.
8. Do not put the system into operation unless correct primary and secondary voltages are measured.

Circuit Breaker (All SOF, All 75F Models only)
Overloading the ATl 50F or ATl 75F Transformer results in tripping the circuit breaker. If the secondary side of the transformer is short circuited, the circuit breaker trips in less than one minute. Reset the circuit breaker by pressing the reset button on the top of the transformer. It can take up to one hour for the transformer to cool, allowing it to reset. If the circuit breaker continues to trip, thoroughly check the system for short circuits and the current draw.

Resideo Technologies, Inc.
1985 Douglas Drive North, Golden Valley, MN 55422
1-800-468-1502
68-0054-06 M.S. Rev. 03-21 I Printed in United States
www.resideo.com
© 2021 Resideo Technologies, Inc. All rights reserved.
This product is manufactured by Resideo Technologies, Inc. and its affiliates.

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