UL 484 CRD-2014 UL Standard for Safety Room Air Conditioners - Section Paragraph Reference Supplement SC Subject Alternative Path for Electronic Controls (Edition 9 February 7 201.pdf

1、UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULUNDERWRITERS LABORATORIES INC. CERTIFICATION REQUIREMENT DECISIONThis Certification Requirement Decision is prepared and published by Underwriters Laboratories Inc.(UL). It is normative for the a

2、pplicable UL Product Certification Program(s); however, it is currently notpart of the UL Standard(s) referenced below.Product Category (CCN): ACOT, ACKZ, ACVSStandard Number: UL 484Standard Title: Standard for Room Air ConditionersEdition Date: February 7, 2014Edition Number: 9Section / Paragraph R

3、eference: Supplement SCSubject: Alternative Path for Electronic ControlsDECISION:IEC. This material is reproduced from IEC 60335-1 with permission of the American National Standards Institute (ANSI) on behalfof the International Electrotechnical Commission. All rights reserved.SUPPLEMENT SC ALTERNAT

4、IVE PATH FOR ELECTRONIC CONTROLS REQUIREMENTSINTRODUCTIONSC1 ScopeSC1.1 Throughout the Supplement, when reference is made to requirements in “this Standard,” thereference is to requirements in the main body of the Standard and not to other requirements of theSupplement.SC1.2 These requirements provi

5、de an alternative path for investigation of electronic controls used inappliances covered by this standard.SC1.3 In the context of this Supplement, an electronic control is a circuit incorporating at least oneelectronic component and that causes the intended output of the appliance energy source(s)

6、(e.g. heaters,moving parts, humidity, radiation) to vary.SC1.4 In the context of this Supplement a motor speed drive would be considered an electronic control.SC1.5 Circuits that transmit or receive signals (analog or digital), transform or convert electricity to supplyother circuits (e.g. power sup

7、ply) or simply switch an electrical load (e.g. electronic relay) are not controlsbut are subject to the requirements of this Supplement when they are integrated (physically or functionally)with a control.SC1.6 A self-regulating PTC heater is not considered a control from the perspective of this Supp

8、lement.When a thermistor is used as a sensor or as part of a thermal management function of a control, it isinvestigated as part of the control.SC1.7 The functional safety requirements for smart or remotely enabled are specified in Supplement SB.SC1.8 Thermal motor protectors in direct contact with

9、motor windings and intended for direct control ofthe motor supply are outside the scope of this Supplement even if they incorporate one or more electroniccomponents.UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULException No.1: Electronic cir

10、cuits that provide thermal motor protection but only have a thermal sensorin direct contact with motor windings are within the scope.Exception No. 2: Electromechanical thermal motor protectors in direct contact with the motor windingswhere the protector is connected to electronic circuits that provi

11、de the motor load control are within thescope.SC1.9 Electronic circuits that provide control functions intended to prevent special hazards such as anexplosion or whose failure could directly cause a hazard in the appliance are outside the scope of thisSupplement.SC2 GeneralSC2.1 The requirements of

12、this Supplement are intended to apply to the electronic control and how thecontrol is integrated in the appliance. The overall appliance construction, performance testing and markingrequirements are applicable as specified in this Standard except as cited in the following requirements.SC3 GlossarySC

13、3.1 CAPACITOR, CLASSXAcapacitor suitable for use in situations where failure of the capacitoror RC unit would not lead to an increased risk of electric shock but could result in an increased risk of fire.Examples would be capacitors connected phase to phase or phase to neutral.SC3.2 CAPACITOR, CLASS

14、YAcapacitor suitable for use in situations where failure of the capacitormay lead to an increased risk of electric shock. Examples would be capacitors connected across theprimary and secondary circuits where electrical isolation is required to prevent an electric shock orbetween hazardous live parts

15、 and accessible parts.SC3.3 DANGEROUS MALFUNCTION Unintended operation of the appliance that may impair safety.Operating Control functions whose failure would result in a Dangerous Malfunction would be consideredSafety Critical Functions. See clause SC3.10.Note 1 Electronic circuits execute varying

16、functions that are integrated within a control or appliance. Some of these functions areevoked during the normal operation of the product to either optimize performance or reduce overstressing of components whileothers are designated to address abnormal operation of the product due to load failures.

17、 Dangerous malfunction addresses thecorrectness of those functions that operate during normal operation of the appliance. A failure of the function to operate correctlycould lead to a hazardous condition.Note 2 Control functions whose failure might result in a Dangerous Malfunction would include:a)

18、An operating control function necessary to comply with the Temperature Test, Section 48 of this Standard.b) A function to prevent the unexpected operation of the appliance from a stand-by mode where the operation wouldresult in an increased risk of electric shock, fire or injury to persons.c) An ele

19、ctronic disconnection circuit whose failure may increase the risk of fire, electric shock or injury to persons.Example 1: An example would be the unattended energization of a heating appliance. The user might haveplaced flammable materials near the appliance based on the assumption the appliance wou

20、ld remain off.Example 2: An example would be the unexpected energization of an appliance with hazardous rotating parts.d) Interlocks necessary for the safe operation of the appliance.STANDARD NUMBER: UL 484 -2-UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PER

21、MISSION FROM ULe) Scald protection provided by the operating control of an electric water heater.f) A zero-cross switching function to allow the use of low capacity switching devices to control higher loads.SC3.4 ELECTRONIC DISCONNECTION The de-energizing of the functional load of the appliance byan

22、 electronic device of a circuit with no air gap.SC3.5 HAZARD OF ITSELF The risk of fire or electric shock emanating from the electronic control only.SC3.6 INTENTIONALLY WEAK PART A part intended to rupture under conditions of abnormaloperation to prevent the occurrence of a condition which could imp

23、air compliance with this standard.SC3.7 LOW-POWER CIRCUIT A circuit or parts of circuits farther from the supply source than alow-power point.SC3.8 LOW-POWER POINT A point closest to the supply source in an electronic circuit where themaximum available power to an external load at the end of 5 secon

24、ds does not exceed 15 watts.SC3.9 PROTECTIVE ELECTRONIC CIRCUIT (PEC) An electronic circuit that prevents a hazardoussituation under abnormal operating conditions. The function of a Protective Electronic Circuit would beconsidered a Safety Critical Function. See clause SC3.10.SC3.10 SAFETY CRITICAL

25、FUNCTION Control, protection and monitoring functions which are beingrelied upon to reduce the risk of fire, electric shock or injury to persons.CONSTRUCTIONSC4 ComponentsSC4.1 Temperature sensing, thermistor devicesSC4.1.1 A temperature sensing device, such as a positive temperature coefficient (PT

26、C) thermistor and anegative temperature coefficient (NTC) thermistor, that performs a Class B control function shall complywith Annex J of the Standard for Automatic Electrical Controls for Household and Similar Use, Part 1:General Requirements, UL 60730-1, or the Standard for Thermistor-Type Device

27、s, UL 1434. Theminimum number of cycles shall be as specified in this standard. See clause 60, HeaterTemperature-Limiting Control Tests; and clause 24, Switches and Controllers.SC4.1.2 The calibration tolerance for a thermistor performing a protective control function shall be asspecified in clause

28、60, Heater Temperature-Limiting Control Tests; and clause 24, Switches andControllers.SC4.2 Printed wiring boardsSC4.2.1 Printed wiring boards shall comply with the Standard for Printed Wiring Boards, UL 796, and shallhave a flammability rating and other characteristics as specified in this Standard

29、.Exception: A printed circuit board solely in a Low-Power Circuit need not comply with UL 796.SC4.2.2 Any printed wiring board that complies with the requirements for Direct Support in the Standardfor Printed Wiring Boards, UL 796, is considered to provide an insulating base with a ComparativeTracki

30、ng Index (CTI) of minimum 100.STANDARD NUMBER: UL 484 -3-UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULSC5 EnclosureSC5.1 The enclosure of an electronic control shall comply with the appliance enclosure requirementsspecified in this Standard

31、.SC6 Field ConnectionsSC6.1 Provision for connection of external data or communication networks (wired or wireless) shallcomply with the requirements of the Standard for Information Technology Equipment Safety Part 1:General Requirements, UL 60950-1.SC6.2 Electronic controls that respond to external

32、 communication signals or data shall comply with therequirements of this Supplement.Exception: A communication device that is not integral with the electronic control (e.g. wholly located ona separate circuit board) and complying with the Standard for Information Technology Equipment Safety Part 1:

33、General Requirements, UL 60950-1, is considered to fulfill this requirement.SC6.3 Connections from the appliance intended to power remote devices shall be powered by sourcescomplying with the requirements of one of the following:a) The Standard for Class 2 Power Units, UL 1310, orb) The Standard for

34、 Low Voltage Transformers Part 1: General Requirements, UL 5085-1;and The Standard for Low Voltage Transformers Part 3: Class 2 and Class 3 Transformers,UL 5085-3 as a Class 2 transformer.c) The Standard for Information Technology Equipment Safety Part 1: GeneralRequirements, UL 60950-1, as a Safety

35、 Extra Low Voltage and Limited Power Source.SC7 Electrical SpacingSC7.1 Electrical spacing between uninsulated live parts of an electronic control and between theuninsulated live parts of an electronic control and accessible metal parts of the rest of the appliance shallcomply with the electrical sp

36、acing requirements specified in this Standard.Exception No. 1: Electrical spacing (through air or over insulating surfaces) may instead comply with therequirements for Creepage Distances, Clearances and Distances Through Solid Insulation of theStandard for Safety of Household and Similar Electrical

37、Appliances, Part 1: General Requirements, UL60335-1 (Clause 29). The anticipated Pollution Degrees and Overvoltage Categories are as shown intable 35.1 and 35.2 of this Standard.Exception No. 2: Electrical spacing (through air or over insulating surfaces) may instead comply with therequirements in t

38、he Standard for Insulation Coordination Including Clearances and Creepage Distancesfor Electrical Equipment, UL 840. The anticipated Pollution Degrees and Overvoltage Categories are asshown in table 35.1 and 35.2 of this Standard.SC7.2 The conductors of different circuits shall be separated in accor

39、dance with the requirementsspecified in this Standard.SC8 Electrical InsulationSTANDARD NUMBER: UL 484 -4-UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULSC8.1 Materials employed as electrical insulation shall comply with the requirements spec

40、ified in thisStandard.SC9 Control FunctionsSC9.1 GeneralSC9.1.1 Electronic circuits or parts of circuits shall be analyzed to determine if the function of the controlis necessary for compliance with this Standard.SC9.1.2 In the evaluation of electronic circuits, the contacts of relays, contactors, o

41、r other devices thatcycle during the Normal Temperature Test shall be short-circuited.SC9.2 Protective electronic circuits/controlsSC9.2.1 A control or circuit whose function must be relied upon for compliance with an abnormal operationtest of this Standard shall be considered a Protective Electroni

42、c Circuit.SC9.2.2 A control or circuit that activates and must be relied upon during any of the component and otherfaults specified in clause SC15 shall be considered a Protective Electronic Circuit.SC9.2.3 An electronic circuit is not considered a Protective Electronic Circuit if, during the abnorm

43、aloperation tests in this Standard and with the function of the circuit defeated, other independent andreliable protective means is sufficient for compliance with the requirements of this Standard.SC9.2.4 A circuit intended to provide motor overload protection as specified in this Standard shall bec

44、onsidered a Protective Electronic Circuit.SC9.2.5 Protective Electronic Circuits include but are not limited to the following:a) Temperature limiting controlsb) Motor overload protector, overheating protectionc) Pressure limiting deviced) Door switch that provides an interlock functionSC9.3 Operatin

45、g controls or circuits that perform safety critical functionsReserved for future use.SC10 Evaluation of the Different Types of Control CircuitsSC10.1 All types of circuitsSC10.1.1 An electronic control shall have the parameters as specified in this Standard. These include butare not limited to:a) En

46、durance cycles,b) Maximum set-point,STANDARD NUMBER: UL 484 -5-UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULc) Manual or automatic reset.SC10.1.2 An electrical component shall not be connected across the contacts of an electronic control th

47、atoperates during an Abnormal Operation Test of this Standard or otherwise serves a safety function (e.g.interlock).Exception: Electrical components may be connected across the contacts provided that any singlecomponent fault does not result in a loss of protective function.SC10.1.3 All control circ

48、uits shall be evaluated to determine the effects of electronic circuit faults.SC10.1.4 When the applicable faults specified in clause SC15.11 are imposed one at a time they shallnot result in:a) The control being a Hazard of Itself, orb) The loss of a control function of a Protective Electronic Circ

49、uit, orc) The loss of any Safety Critical Function of an operating control.SC10.1.5 The risk of electrically generated fire from the faults of clause SC15.11 is considered to bemitigated in Low-Power Circuits.SC11 Protective Electronic CircuitsSC11.1 Appliances incorporating a Protective Electronic Circuit that relies upon a programmablecomponent for one or more of its safety functions shall incorporate measures to control the fault/errorconditions that would impair the safety functions.SC11.2 The evaluation of the programmable component shall be i