AT72D - Electrical Transformer HONEYWELL - Free user manual and instructions

USER MANUAL AT72D HONEYWELL

The AT20, AT40, AT72, AT87 and AT88 TRADELINE ^® Transformers are step-down transformers used primarily for powering 24 Vac control systems. They can be used in any 24 Vac application that does not exceed the transformer volt-ampere (VA) rating.

The TRADELINE® Transformers will replace all equivalent Honeywell and competitive transformers with similar primary voltage requirements, equal or smaller VA ratings and similar mounting configurations.

Transformer voltage ratings (primary and secondary), wiring connection type, and fusing are listed in Table 1.

The transformers are Underwriters Laboratories Inc. component recognized and Canadian Standards Association listed and meet NEC Class 2 not wet, Class 3 wet requirements as specified by NEMA Standard DC-20.

SPECIFICATIONS

Models:

See Table 1.

Table 1. Transformer Model and Electrical Specifications.

Model	Primary Secondary Output at				100 Percent Power Rating	Overload Protection
	Voltage and Frequency	Wiring Connection Voltage	Voltage	Wiring Connection
AT20^a	120 Vac, 50/60 Hz	Two 9 in. (229 mm) leadwires	24 Vac Two 9	in. (229 mm) leadwires	20 VA Energy	Limitedc
AT40^a	120 Vac, 50/60 Hz	40 VA
	240 Vac, 50/60 Hz
AT72D^a	120 Vac, 50/60 Hz	two screw		terminals
	240 Vac, 50/60 Hz	Three 9 in. (229 mm) leadwires
AT87A^a	120 Vac, 50/60 Hz	Two 13 in. (330 mm) leadwires			50 VA
	208 Vac, 50/60 Hz
	240 Vac, 50/60 Hz
AT88A 120	Vac, 50/60 Hz Two	12 in. (305 mm) leadwires	24 Vac Two 1	2 in. (305 mm) leadwires	75 VA Fuse in	secondary
	208/240 Vac, 50/60 Hz
	400 Vac, 50/60 Hz
	480 Vac, 50/60 Hz^b

^a Transformer complies with 24 volt NEMA Standard DC-20.

^b Available with female quick-connect terminals on all leadwires.

^c Thermal fuses in primary on 208V/240V models for overload protection.

INSTALLATION

	A		B		C				D
	in.	mm	in.	mm	in.	mm	in.	mm	in.
AT40C2	-13/3261	7/822	-3/4	442-3	16562	-7/873
AT87A2	-13/3261	1	251-3	4442	-1/1652	3	76

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. The installer must be a trained, experienced service technician.
4. After installation is complete, check out product operation as provided in these instructions.

WARNING

Electrical Shock Hazard. Can cause severe injury, death or property damage.

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

Mounting the AT20A and AT40A Transformer

1. Mount the transformer to best suit the replacement application. The transformer may be mounted in one of three ways: a. Use bolts in slots for direct mounting (Fig. 1).

PANEL MOUNTING USE WASHERS IF NECESSARY M20654

Fig. 1. Use bolts in slots for panel mounting.

b. Horizontal channel frame. Place frame over laminations as shown in Fig. 3 and bend tabs over to hold transformer securely in place. Mount transformer over 3/16 in. (5 mm) holes in mounting feet.

E mm MOUNTING FOOT (2) USE SCREWS OR BOLTS THROUGH SLOTS (4) IN MOUNTING FEET M20655

Fig. 2. Foot mounting (AT20C shown).

c. Vertical channel mounting. Place frame over laminations as shown in Fig. 3 and bend tabs over to hold transformer securely in place. Mount transformer through 3/16 in. (5 mm) holes in mounting feet.

HORIZONTAL FOOT MOUNTING USE WASHERS IF NECESSARY BEND OVER TABS (4) TO SECURE TRANSFORMER M20665 VERTICAL FOOT MOUNTING USE WASHERS IF NECESSARY BEND OVER TABS (4) TO SECURE TRANSFORMER M20657

Fig. 3. Use horizontal channel frame for horizontal foot mounting; vertical channel frame for vertical foot mounting.

Mounting the AT72D Transformer.

Mount the transformer to meet the application. Use one of the methods illustrated. The transformer can be mounted in any position.

Foot Mounting.

1. Discard mounting plate.
2. Use screws or bolts through slots in mounting feet to fasten transformer to mounting surface (see Fig. 2).

Plate Mounting.

The mounting plate allows the transformer to be mounted on a 4 in. by 4 in. square or 4 in. octagonal junction box.

1. Remove the large center knockout in the mounting plate (Fig. 6).
2. Take transformer in one hand and mounting plate in the other hand. Keyhole slots on mounting plate should be up.
3. Place large knockout in mounting plate over primary leadwires and end bell of transformer. The small tab on the bottom center of the plate fits into the slot in the transformer mounting feet (Fig. 7).
4. Insert the mounting screw through the holes as illustrated.
5. Secure the plate to the transformer. Do not overtighten.

Mounting plate to transformer (Fig. 4).

The plate can be mounted to the transformer in one of two positions:

a. at the clamp on primary end bell (transformer all above plate);
b. at the laminations (transformer 3/4 above plate. To mount the plate at clamp on primary end bell (transformer all above plate):

1. Take mounting plate in one hand. Keep the key-hole slots up and the raised portion of the large center knockout toward you.
2. Insert the primary leadwires through the center hole in the plate.

3. Fit the hole in the plate over the clamp attached to the end bell. Clamp screw must be turned almost completely out.

4. With the plate in place over the clamp, tighten the screw securely against the rim of the round hold See Fig. 5. Avoid damaging the leadwires with the screwdriver.

To mount the plate at the laminations (transformer 3/4 above the mounting plate:

1. Remove the large center knockout in the mounting plate (see Fig. 6).
2. Take the transformer in one hand. Clamp on end bell should face you.
3. Take the mounting plate in the other hand. Key-hole slots should be up.

4. Place large knockout in mounting plate over primary leadwires and end bell. Small tab at the bottom of the center of the plate fits into the transformer mounting foot (Fig. 7). Insert mounting screw through holes as shown in Fig. 8.

5. Secure plate to transformer. Do not overtighten screw.

Mounting Transformer and Plate to Electrical Box

The mounting plate can be mounted to 4 in. x 4 in. boxes with regular and irregular spaced mounting holes, to 2 in by 4 in. boxes and to 4 in. octagonal boxes. See Fig. 9.

1. Use the screws supplied with the electrical box.
2. Place them through the proper mounting holes in the plate and secure the transformer and plate to the box.
3. Punch out appropriate knockouts for plate mounting holes, if necessary.

NOTE: Transformer feet should always be outside of the junction box.

Clamp Mounting Using Junction Box Knockout

The transformer can also be clamp mounted using a junction box knockout, if desired. This mounting option does not require the use of the mounting plate. To mount the transformer within the knockout:

1. Insert the primary leadwires and clamp and screw on transformer end bell through suitable 1/2 in. (13 mm) knockout in junction box. Clamp screw must be turned almost completely out in order to get clamp through knockout.
2. Tighten clamp screw securely against rim of knockout. Avoid damaging the leadwires with the screwdriver.

PLATE MOUNTED AT CLAMP ON END BELL (ALL ABOVE PLATE MOUNTING)

MOUNTING PLATE END BELL CLAMP SCREW AND CLAMP LEADWIRES FOR PRIMARY CONNECTIONS RAISED PORTION OF LARGE CENTER KNOCKOUT SCREW TERMINALS FOR SECONDARY CONNECTIONS

PLATE MOUNTED AT THE LAMINATIONS (3/4 ABOVE PLATE MOUNTING)

LEADWIRES FOR PRIMARY CONNECTIONS MOUNTING PLATE MOUNTING SCREW SCREW TERMINALS FOR SECONDARY CONNECTIONS M20656

Fig. 4. Plate may be mounted to transformer in one of two positions (AT72D shown).

IMPORTANT MOUNT TRANSFORMER OTHER SIDE M12126

Fig. 5. Tighten clamp securely against rim of round hole.

WITH RAISED PORTION OF KNOCKOUTS FACING YOU:

1. PRY UP TOP SECTION OF LARGE KNOCKOUT BY INSERTING SCREWDRIVER FIRST AT ONE SIDE OF SLOT AND THEN AT THE OTHER SIDE.

Pure technical diagram of a mechanical component without any text, numbers, or symbols

THEN PRY UP BOTTOM SECTION OF KNOCKOUT.2.

Pure technical diagram of a mechanical component with no text, numbers, or symbols

REMOVE BOTH SECTIONS OF KNOCKOUT WITH PLIERS.3.

SHADED AREAS REPRESENT KNOCKOUTS AND SCREW SLOTS USED WITH 2 X 4 INCH OR OCTAGONAL OUTLET BOXES.

M9188A

Fig. 6. Removing large center knockout.

SLOT TAB M20855

Fig. 7. Tab on mounting plate fits in slot on transformer mounting foot.

TRANSFORMER PLATE IMPORTAN T MOUNT TRANSFORMER OTHER SIDE M9163

Fig. 8. Secure plate to transformer with mounting screw.

REGULAR 4 X 4 INCH BOX (2) OCTAGON BOX IRREGULAR 4 X 4 INCH BOX (MOUNTING HOLES IN BOX ARE SLIGHTLY INDENTED) LOAD N.E.C. CLASS 2 IRREGULAR 4 X 4 INCH BOX (MOUNTING HOLES IN BOX ARE SLIGHTLY INDENTED) OCTAGON BOX REGULAR 4 X 4 INCH BOX (2) M20658

Fig. 9. Location of mounting holes.

Mounting the AT87 Transformer

Foot Mounting (Fig. 10)

Use screws or bolts through slots in the mounting feet to fasten the transformer to the mounting surface.

USE SCREWS OR BOLTS THROUGH SLOTS (4) IN MOUNTING FEET LEADWIRES FOR PRIMARY CONNECTIONS SCREW TERMINALS FOR SECONDARY CONNECTIONS MOUNTING FOOT (2) M20659

Fig. 10. Foot mounting of AT87 Transformer.

Plate Mounting

The mounting plate allows the transformer to be mounted on a 4 in. by 4 in. square or 4 in. octagonal junction box.

1. Remove the large center knockout in the mounting plate (see Fig. 6).
2. Take transformer in one hand and mounting plate in the other hand. Keyhole slots on mounting plate should be up.
3. Place large knockout in mounting plate over primary leadwires and end bell of transformer. The small tab on the bottom center of the plate fits into the slot in the transformer mounting feet (see Fig. 7).
4. Insert the mounting screw through the holes as illustrated (Fig. 8).
5. Secure plate to transformer. Do not overtighten screw.

Mounting Transformer and Plate to Electrical Box.

The mounting plate can be mounted in 4 in. x 4 in. boxes with regular and irregular spaced mounting holes, and on 4 in. octagonal boxes (Fig. 9).

1. Use the screws supplied with the junction box.
2. Place the screws through the appropriate mounting holes in the plate and secure the transformer and plate to the box.
3. Punch out appropriate knockouts for plate mounting holes, as necessary.

NOTE: Transformer should always be outside of the junction box.

Mounting the AT88 Transformer.

Use screws or bolts through slots in the mounting feet to fasten the transformer to the mounting surface. See Fig. 2.

WIRING

1. Disconnect power supply before installing transformer. All wiring must comply with local electrical codes and ordinances. Tape all unused exposed leadwires separately.
2. Connect primary leadwires to line voltage power supply. See Fig. 11 through 13.
3. Connect transformer secondary leadwires to 24 Vac control system.

COMMON BLACK WHITE (120V) OR ORANGE (240V) 2 1 24 VAC

1 SECONDARY CONNECTIONS ARE BLUE AND YELLOW LEADWIRES.
2 BLACK IS COMMON WITH RESPECT TO THE TRANSFORMER WINDING ONLY AND NOT THE EXTERNAL CIRCUIT.

M20660

Fig. 11. AT20/AT40 Transformer schematic.

2 BLACK 120 VAC WHITE 208 VAC RED 240 VAC ORANGE 1 24 VAC SECONDARY CONNECTIONS ARE SCREW TERMINALS. 2 BLACK IS COMMON WITH RESPECT TO THE TRANSFORMER WINDING AND NOT THE EXTERNAL CIRCUIT. M18321

Fig. 12. AT72D, AT87A Transformer schematic.

COMMON 208 VAC BLACK 240 VAC RED ORANGE 1 24 VAC

1 SECONDARY CONNECTIONS ARE BLUE AND YELLOW LEADWIRES.
2 BLACK IS COMMON WITH RESPECT TO THE TRANSFORMER WINDING ONLY AND NOT THE EXTERNAL CIRCUIT.

M20661

Fig. 13. AT88 Transformer schematic.

CHECKOUT

After installation is complete, turn on power supply. Placed controlled equipment into operation and observe through at least one complete cycle. Make sure it functions as intended.

Honeywell

Transformateurs AT AT20, AT40, AT72D, AT87, AT88

NOTICE D'INSTALLATION

APPLICATION

IMPORTANT MOUNT TRANSFORMER OTHER SIDE M12126

Pure technical diagram of a mechanical component without any text, numbers, or symbols

Pure technical diagram of a mechanical component with no text, numbers, or symbols

1. ENLEVER LE DEUX PARTIES DE L'OUVERTURE DEFONÇABLE À L'AIDE DE PINCES.

PARTIES OMBRÉES: OUVERTURES DÉFONÇABLES ET FENTES POUR LES VIS À UTILISER AVEC LES BOÎTES DE 2 PO SUR 4 PO OU LES BOÎTES OCTOGONALES.

MF9188B

Honeywell International Inc.

1985 Douglas Drive North

Golden Valley, MN 55422

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© 2016 Honeywell International Inc.

69-1641EF-01 M.S. Rev. 08-16