4301 NORTH FAIRFAX DRIVE ! ARLINGTON, VIRGINIA 22203

Standard 780/790

1997STANDARD for

DEFINITEPURPOSE ANDLIMITED DUTYDEFINITEPURPOSEMAGNETICCONTACTORS

Price $10.00 (M) $20.00 (NM) ©Copyright 1997, by Air-Conditioning and Refrigeration InstitutePrinted in U.S.A. Registered United States Patent and Trademark Office

IMPORTANT

SAFETY RECOMMENDATIONS

It is strongly recommended that the product be designed, constructed, assembled and installed in accordance withnationally recognized safety requirements appropriate for products covered by this standard.

ARI, as a manufacturers' trade association, uses its best efforts to develop standards employing state-of-the-art andaccepted industry practices. However, ARI does not certify or guarantee safety of any products, components orsystems designed, tested, rated, installed or operated in accordance with these standards or that any tests conductedunder its standards will be non-hazardous or free from risk.

Note:

This standard supersedes ARI Standards 780-86 and 790-86.

TABLE OF CONTENTS

SECTION PAGE

Section 1. Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Section 2. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Section 3. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Section 4. Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Section 5. Sizes and Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Section 6. Test Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Section 7. Performance Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Section 8. Minimum Data Requirements for Published Ratings . . . . . . . . . . . . . . . . . . . 6

Section 9. Marking and Nameplate Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Section 10. Voluntary Conformance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

TABLES

Table 1. Sizes and Ratings - Definite Purpose and Limited Duty Contactors . . . . . . . 2

Table 2. Load Test Voltages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

FIGURES

Figure 1. Load Test Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

APPENDICES

Appendix A. References - Normative . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Appendix B. References - Informative . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

ARI STANDARD 780/790-97

1

DEFINITE PURPOSE AND LIMITED DUTY DEFINITEPURPOSE MAGNETIC CONTACTORS

Section 1. Purpose the motor protection system and may be either an integral

1.1 Purpose. The purpose of this standard is to establish,for definite purpose and limited duty definite purposemagnetic contactors within its scope: definitions; 3.3 Limited Duty Definite Purpose Magnetic Contactors.classifications; sizes and ratings; requirements for testing A device for repeatedly establishing and interrupting anand performance; minimum data requirements for electric power circuit for application on compressor motors,published ratings; marking and nameplate data; and fan and pump motors, other motors, and resistive heaterconformance conditions. loads, and may be an integral part of an air-conditioning or

1.1.1 Intent. This standard is intended for theguidance of the industry, including manufacturers,engineers, installers, contractors and users.

1.1.2 Review and Amendment. This standard issubject to review and amendment as technologyadvances.

Section 2. Scope compliance with the standard is claimed.

2.1 Scope. This standard applies to contactors intendedfor use in refrigeration and air-conditioning equipment.

2.1.1 Definite Purpose Magnetic Contactors. Thesecontactors are suitable for use with pilot duty protectedcompressor motors where they are part of the motorprotection system. They are also applicable as controlsfor fan motors, pump motors, resistive loads, etc.

2.1.2 Limited Duty Definite Purpose MagneticContactors. These contactors are intended for usewhere the contactor is not part of the compressor motorprotection circuit or primary safety circuit, and mayalso be applicable as controls for fan motors, pumpmotors, resistive loads, etc.

Section 3. Definitions

3.1 Definitions. All terms in this document will followthe standard industry definitions established in the currentedition of ASHRAE Terminology of Heating, Ventilation,Air Conditioning, and Refrigeration, unless otherwisedefined in this section.

3.2 Definite Purpose Magnetic Contactors. A device forrepeatedly establishing and interrupting an electric powercircuit for application on compressor motors, fan and pumpmotors, other motors, and resistive heater loads as part of

part of an air conditioning or refrigeration unit, or mountedon the control panel for such a unit.

refrigeration unit, but where the contactor itself is not apart of the safety circuit or motor protection system of theunit.

3.4 "Shall," "Should," "Recommended" or "It IsRecommended." "Shall," "should," "recommended" or "itis recommended" shall be interpreted as follows:

3.4.1 Shall. Where "shall" or "shall not" is used fora provision specified, that provision is mandatory if

3.4.2 Should, Recommended or It Is Recommended."Should," "recommended" or "it is recommended" isused to indicate provisions which are not mandatorybut which are desirable as good practice.

3.5 Published Rating. A statement of the assigned valuesof those performance characteristics, under stated ratingconditions, by which a unit may be chosen to fit itsapplication. These values apply to all units of like nominalsize and type (identification) produced by the samemanufacturer. As used herein, the term "published rating"includes the rating of all performance in specifications,advertising or other literature controlled by themanufacturer, at stated rating conditions.

3.5.1 Standard Rating. A rating based on testsperformed at Standard Rating Conditions.

3.5.2 Application Rating. A rating based on testsperformed at application rating conditions (conditionsother than Standard Rating Conditions).

Section 4. Classification

4.1 Contactor Classifications. Contactors are classifiedinto two types as defined in Section 3; definite purposemagnetic contactors and limited duty definite purposemagnetic contactors.

ARI STANDARD 780/790-97

2

Table 1. Sizes and Ratings -1, 2

Definite Purpose and Limited DutyContactors

Contactor Size

Full-Load Current(Amperes)

Locked-Rotor Current(Amperes)

240Vor Less

480V 600V

20AR/20ARL25AR/25ARL30AR/30ARL40AR/40ARL50AR/50ARL60AR/60ARL75AR/75ARL90AR/90ARL

2025304050607590

120150180240300360450540

100125150200250300375450

80100120160200240300360

Note 1: These ratings correspond to two-pole single-phase or three-polethree-phase load connections unless the nameplate states thatratings are "per pole." (See 7.9.1)

Note 2: It shall not be construed that other sizes and ratings cannot orwill not be produced.

Section 5. Sizes and Ratings

5.1 Sizes. Contactors of the sizes listed in Table 1 shallbear the ratings shown.

Section 6. Test Requirements

6.1 General Requirements.

6.1.1 Test Samples. Test samples are to be pre-production or production units, not experimental orprototype units. Contactors equipped with auxiliarycontacts shall be tested with those contacts in place.

6.1.2 Required Tests. All test samples shall first besubject to the following test:

6.1.2.1 Pick-Up and Drop-Out. (See 7.2)

A separate sample shall be subjected to each of thefollowing tests:

6.1.2.2 Coil Temperature Tests. (See 7.3)

6.1.2.3 Mechanical Life Test. (See 7.4)

6.1.2.4 Recycle Load Test. (See 7.5)

6.1.2.5 Endurance Load Test. (See 7.6)

6.1.2.6 Environmental Test. (See 7.8)

6.1.3 Optional Test.

6.1.3.1 Part Winding and Two Contactor Test.For definite purpose magnetic contactors only.(See 7.7)

6.1.4 Load Test Voltages. Load test voltages shallbe those shown in Table 2.

Table 2. Load Test Voltages

Nameplate Rated VoltageRange Test Voltage

110-120V 120V200-208V 208V220-240V 240V254-277V 277V440-480V 480V550-600V 600V

Any device rated at a voltage not included in theabove table will be tested at its nameplate ratedvoltage.

6.1.4.1 Supply Circuit. The open circuit voltageof the supply circuit is to be not less than 100%nor more than 110% of the specified test voltage,except that a higher voltage may be employed ifagreeable to those concerned. The currentcarrying capacity of the supply circuit is to be suchthat the closed circuit voltage, with test currentflowing (see 7.5.1 and/or 7.6.1), is within 2-½%of the specified test voltage.

6.1.4.2 Cycling Tests. All cycling tests shall beperformed with random switching relative to theinstantaneous supply voltage. This may beaccomplished by using non-synchronousswitching timers or other equivalent means.

6.1.5 Test Loads. Test loads may be one of thefollowing types:

6.1.5.1 Air-Core Loads, shunted in accordancewith Paragraph. 11.7 of UL Standard 489.

6.1.5.2 Iron-Core Loads, having transientcharacteristics similar to actual motor loads.

6.1.6 Mounting Positions. A device capable ofbeing mounted in more than one position shall betested in the position which, as determined by the

ARI STANDARD 780/790-97

3

contactor manufacturer, imposes the greatest electrical readings, taken at intervals of 10% of theand/or mechanical burden on the contactor. previously elapsed duration of the test, but not less

6.1.7 Line and Load Connections. The line andload conductors shall be 600 volt, 167EF (75EC)copper wire, of the minimum size allowable in Table310-17 of the 1996 edition of the National Electrical 7.2.1.2 Ambient. Ambient temperature shall beCode (no temperature correction factor) for an 150EF ± 5EF [65.6E C ± 2.8EC] in still air (lessampacity of 125% of the contactor full-load rating. than 25 fpm [0.127 m/s]).

Section 7. Performance Requirements

7.1 Dielectric Test.

7.1.1 Line-Voltage Devices. A definite purposemagnetic contactor, mounted on a 12 in. V 12 in. V0.053 in. [304.8 mm V 304.8 mm V 1.35 mm] metalplate, shall be capable of withstanding for one minute,without breakdown, the application of a 60 Hzalternating potential of 1000 volts plus twicemaximum rated voltage:

a. Between uninsulated line-voltage live-metal partsand the mounting plate, with the contacts open andclosed;

b. Between line-voltage terminals of oppositepolarity, with the contacts closed. The holdingcoil of the contactor normally connected betweenlines of opposite polarity shall be disconnectedfrom one side of the line or isolated when makingthis test.

c. Between uninsulated live-metal parts of line- andlow-voltage circuits, and different line-voltagecircuits.

7.1.2 Low-Voltage Devices. A device employing alow-voltage circuit (30 volts or less) shall be capable ofwithstanding for one minute, without breakdown, theapplication of a 60 Hz alternating potential of 500volts applied between uninsulated low-voltage live-metal parts of opposite polarity (with contacts, it any,closed), and between uninsulated low-voltage live-metal parts and the enclosure and grounded dead-metal parts.

7.2 Pick-Up and Drop-Out Test.

7.2.1 Conditions.

7.2.1.1 Temperature Stabilization. The coilshall be subjected to 100 percent of the coil testvoltage (see 7.3.1.3), with no load on contacts,until its temperature is constant. Temperature isconsidered to be constant when three successive

than five-minute intervals, indicated no change.Temperature measurements by thermocouple orresistance method are acceptable.

7.2.1.3 Voltage Application/Removal Rate.Voltage application/removal rate shall be 5% ofnominal coil voltage per second.

7.2.2 Requirements.

7.2.2.1 Pick-Up and Drop-Out Voltages. Onslowly rising voltage under conditions 7.2.1, theseal voltage shall be equal to or less than the pick-up voltage. On slowly falling voltage, thecontactor shall remain sealed until drop-outoccurs. Drop-out voltage shall be at least 10%less than the pick-up voltage.

7.2.2.2 Low-Voltage Pick-Up and Seal. Thecontactor shall pick-up and seal at 85% or less ofrated voltage, with the coil hot (see 7.2.1.1).

7.3 Coil Temperature Tests.

7.3.1 Conditions.

7.3.1.1 Temperature Stabi l izat ion.Temperatures shall be stabilized by the procedureoutlined in 7.2.1.1.

7.3.1.2 Load Current. The load current shall be125% of the rated current on each pole (lowvoltage source may be used). (Auxiliary poleloaded per its rating.)

7.3.1.3 Voltage. The coil test voltage shall be24, 120, 208, 240, 480 or 600V for 60 Hz ratings.For the temperature test, the coil voltage shall be105% of the test voltage. For 50 Hz and otherfrequency ratings, the coil temperature test shallbe conducted with a coil voltage of 110% of themanufacturers' voltage rating and the specifiedfrequency or 105% of the 60 Hz test voltage.

7.3.1.3.1 For single winding, dual or multivoltage coils, the test shall be conducted onthe highest voltage winding at 60 Hz. (Coilvoltage, 105% of the test voltage.)

ARI STANDARD 780/790-97

4

7.3.1.3.2 For multi-winding 60 Hz coils the 7.5.1.1 Load Cycle. Make and break lockedtest shall be conducted on each winding and rotor current at test voltage.each combination of windings. (Coil voltage,105% of the test voltage.)

7.3.1.4 Mounting. The device is to be mounted three-phase--50%on a 12 in. V 12 in. V 0.053 in. [304.8 mm V304.8 mm V 1.35 mm] metal plate for this test.

7.3.1.5 Ambient. Ambient temperature shall be off time--Ratio of off time to on time;150EF ± 5EF [65.6EC ± 2.8EC] in still air (less to be 20 to 1, maximumthan 25 fpm [0.127 m/s]).

7.3.1.6 Temperature Measurement. Coil 70 to 90EF [21.1 to 32.2EC].temperature shall be measured by the resistancemethod; other temperatures, by the thermocouplemethod.

7.3.1.7 Selection for Test. Not less than sixunits of the same voltage rating are to be checkedfor coil wattage, and the one with the highestwattage shall be subjected to temperature test.

7.3.2 Requirements. The final temperature of thecoil in still air (less than 25 fpm [0.127 m/s]) shall notexceed a temperature of 230EF [110EC] for Class Acoil insulation and 266EF [130EC] for Class B coilinsulation or 284EF [140EC] for Class F insulation.

7.4 Mechanical Life Test.

7.4.1 Conditions.

7.4.1.1 Ambient. The ambient temperature shallbe 150EF ± 5EF [65.6EC ± 2.8E C].

7.4.1.2 Voltage. The coil voltage shall be 105%test voltage (see 7.3.1.3).

7.4.1.3 Load. There shall be no load on thecontacts.

7.4.1.4 Cycling Rate. The cycling rate shall be single-phase--50%such that it assures full motion of the moving three-phase--50%parts of the device and shall be no slower than 0.5 b. Full load current:second on and 0.5 second off. single-phase--80%

7.4.2 Requirements. There shall be no mechanicalmalfunction in 500,000 operations. After completion 7.6.1.3 Cycle rate:of the test, the device shall pass the Dielectric Test (see7.1) and the Pick-Up and Drop-Out test (see 7.2). on time--1 sec. (0.25 sec. locked rotor

7.5 Recycle Load Test.

7.5.1 Conditions.

7.5.1.2 Maximum power factor:single-phase--50%

7.5.1.3 Cycle rate:on time--0.5 to 2 sec.

7.5.1.4 Ambient. Ambient temperature shall be

7.5.1.5 Voltage. The coil voltage shall be 100%of the coil test voltage (see 7.3.1.3).

7.5.2 Requirements.

7.5.2.1 Definite Purpose Magnetic Contactor.The contactor shall withstand 10,000 operationswith no failure. After completion of this test, thedevice shall pass the Dielectric Test (see 7.1) (Onesample for each load test.).

7.5.2.2 Limited Duty Definite Purpose MagneticContactor. The contactor shall withstand 1000operations with no failure. After completion ofthe test, the device shall pass the Dielectric Test(see 7.1). (One sample for each load test.)

7.6 Endurance Load Test.

7.6.1 Conditions.

7.6.1.1 Load Cycle. Make locked rotor currentand break 125% full load current at test voltage.

7.6.1.2 Maximum Power factor:

a. Locked rotor current:

three-phase--80%

current, 0.75 sec. 125 percent full loadcurrent)off time--9 sec.

ARI STANDARD 780/790-97

5

7.6.1.4 Ambient. Ambient temperature shall be 7.7.1.6 Requirements. The contactor shall70 to 90EF [21.1 to 32.2EC]. withstand 30,000 operations with no failure,

7.6.1.5 Test Voltage. The coil voltage shall be100% of the test voltage per 7.3.1.3. 7.8 Environmental Test. Devices shall be maintained

7.6.2 Requirements.

7.6.2.1 Definite Purpose Magnetic Contactor.The contactor shall withstand 200,000 operationswith no failure. After completion of the test, thedevice shall pass the Dielectric Test (see 7.1).(One sample for each load test.)

7.6.2.2 Limited Duty Definite Purpose MagneticContactor. The contactor shall withstand 100,000operations with no failure. After completion ofthe test, the device shall pass the Dielectric Test(see 7.1). (One sample for each load test.)

7.7 Part Winding and Two Contactor Test (Optional) forDefinite Purpose Contactors Only.

(NOT FOR LIMITED DUTY DEFINITE PURPOSEMAGNETIC CONTACTORS.)

7.7.1 Qualifications. If the manufacturer desires toqualify the contactor for either two contactor across theline, or two contactor part-winding start application,the following test criteria shall apply.

7.7.1.1 Load Cycle. Make full load current andbreak, locked rotor current at test voltage. (If themanufacturer desires to derate the contactor to80% of its normal rating for two contactorapplications, the test may be run making full loadcurrent and breaking 80% of rated locked rotorcurrent.)

7.7.1.2 Maximum power factor:

a. Locked rotor current--50%b. Full load current--80%

7.7.1.3 Cycle Rate:

on time--1 sec. (0.75 second full loadcurrent, 0.25 sec. locked rotor current)off time--9 sec.

7.7.1.4 Ambient. Ambient temperature shall be70 to 90EF [21.1 to 32.2EC].

7.7.1.5 Voltage. The coil voltage shall be 100%of the test voltage (see 7.3.1.3).

followed by a Dielectric Test (see 7.1).

without energizing in the following environments for atotal of 10 cycles:

a. Hold for 15 hours at 110EF [43.3EC], 90-95% R.H.b. Reduced temperature and humidity gradually over

a 2.5 hour period to 40EF [4.4EC] and 30-50%R.H.

c. Hold for 4 hours at 40EF [4.4EC], 30-50% R.H.d. Increase temperature and humidity gradually over

a 2.5 hour period to 110EF [43.3EC], 90-95% R.H.At the end of the 10th 24-hour cycle, increasetemperature to room temperature (instead of 110EF[43.3EC]) and maintain for 2 hours.

Note: Condensation on devices being tested isnot permitted.

7.8.1 Requirements. At the conclusion of theconditioning period:

a. Devices shall operate normally with noevidence of sticking, either open or closed,when Pick-Up and Drop-Out Test isperformed (see 7.2).

b. Devices shall not exhibit corrosion of internalparts or evidence of any dimensionalinstability of parts which could interfere withnormal operation.

c. After completion of the test, the device shallpass the Dielectric Test (see 7.1) afterremaining at room temperature for two hours.

7.9 Load Connections.

7.9.1 Load Test Connections. Load connectionsshall be chosen from Figure 1, for the tests describedin 7.5, 7.6 and 7.7.

7.9.2 Grounding Circuit. For a grounded-neutralsystem, the enclosure shall be connected during the testthrough a 3-ampere cartridge fuse to the groundedconductor of the circuit. For any other system, theenclosure shall be connected through such a fuse to thelive pole least likely to strike (arc) to ground. The fuseshall not open as a result of this test.

ARI STANDARD 780/790-97

6

Figure 1. Load Test Diagrams

Section 8. Minimum Data Requirements for Recommended nameplate voltages for 60 Hertz systemsPublished Ratings shall include one or more of the equipment nameplate

8.1 Published Ratings. Any published ratings such as incatalogs, specification sheets, advertising literature, etc.shall have the classification as Definite Purpose or LimitedDuty Definite Purpose, clearly identified.

Section 9. Marking and Nameplate Data

9.1 Marking and Nameplate Data. The contactor shalldisplay the manufacturer's name, model designation,contactor type, electrical characteristics and "Limited DutyDefinite Purpose" if applicable.

voltage ratings shown in Table 1 of ARI Standard 110.Recommended nameplate voltages for 50 Hertz systemsshall include one or more of the utilization voltages shownin Table 1 of IEC Standard Publication 38.

Section 10. Voluntary Conformance

10.1 Conformance. While conformance with thisstandard is completely voluntary, conformance shall not beclaimed or implied for products or equipment within itsPurpose (Section 1) and Scope (Section 2) unless suchclaims meet all of the requirements of the Standard.

ARI STANDARD 780/790-97

7

APPENDIX A. REFERENCES - NORMATIVE

A.1 Listed here are all standards, handbooks, and other A1.3 IEC Standard Publication 38, IEC Standardpublications essential to the formation and implementation Voltages, 1983, International Electrotechnicalof the standard. All references in this appendix are Commission, 3 rue de Varembe, P.O. Box 131, 1211considered as part of this standard. Geneva 20, Switzerland.

A1.1 ARI Standard 110-97, Air-Conditioning and A1.4 National Electrical Code, 1996, National FireRefrigerating Equipment Nameplate Voltages, 1997, Protection Association, 1 Batterymarch Park, Quincy,Air-Conditioning and Refrigeration Institute, 4301 MA 02269, U.S.A.North Fairfax Drive, Suite 425, Arlington, VA 22203,U.S.A.

A1.2 ASHRAE Terminology of Heating, Eighth Edition, 1991, Underwriters Laboratories, Inc.,Ventilation, Air Conditioning and Refrigeration, 333 Pfingsten Road, Northbrook, IL 60062, U.S.A.American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc., 1791 Tullie Circle N.E.,Atlanta, GA 30329, U.S.A.

A1.5 UL Standard for Safety 489, Molded-CaseCircuit Breakers and Circuit-Breaker Enclosures,

APPENDIX B. REFERENCES - INFORMATIVENone.