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1、 NEMA DC 10 RESIDENTIAL CONTROLS TEMPERATURE LIMIT CONTROLS FOR ELECTRICAL BASEBOARD HEATERS NEMA Standards Publication DC 10-2009 Residential ControlsTemperature Limit Controls for Electrical Baseboard Heaters Published by: National Electrical Manufacturers Association 1300 North 17th Street Rossly
2、n, Virginia 22209 www.nema.org Copyright 2009 by the National Electrical Manufacturers Association. All rights including translation into other languages, reserved under the Universal Copyright Convention, the Berne Convention for the Protection of Literary and Artistic Works, and the International
3、and Pan American Copyright Conventions. NOTICE AND DISCLAIMER The information in this publication was considered technically sound by the consensus of persons engaged in the development and approval of the document at the time it was developed. Consensus does not necessarily mean that there is unani
4、mous agreement among every person participating in the development of this document. The National Electrical Manufacturers Association (NEMA) standards and guideline publications, of which the document contained herein is one, are developed through a voluntary consensus standards development process
5、. This process brings together volunteers and/or seeks out the views of persons who have an interest in the topic covered by this publication. While NEMA administers the process and establishes rules to promote fairness in the development of consensus, it does not write the document and it does not
6、independently test, evaluate, or verify the accuracy or completeness of any information or the soundness of any judgments contained in its standards and guideline publications. NEMA disclaims liability for any personal injury, property, or other damages of any nature whatsoever, whether special, ind
7、irect, consequential, or compensatory, directly or indirectly resulting from the publication, use of, application, or reliance on this document. NEMA disclaims and makes no guaranty or warranty, expressed or implied, as to the accuracy or completeness of any information published herein, and disclai
8、ms and makes no warranty that the information in this document will fulfill any of your particular purposes or needs. NEMA does not undertake to guarantee the performance of any individual manufacturer or sellers products or services by virtue of this standard or guide. In publishing and making this
9、 document available, NEMA is not undertaking to render professional or other services for or on behalf of any person or entity, nor is NEMA undertaking to perform any duty owed by any person or entity to someone else. Anyone using this document should rely on his or her own independent judgment or,
10、as appropriate, seek the advice of a competent professional in determining the exercise of reasonable care in any given circumstances. Information and other standards on the topic covered by this publication may be available from other sources, which the user may wish to consult for additional views
11、 or information not covered by this publication. NEMA has no power, nor does it undertake to police or enforce compliance with the contents of this document. NEMA does not certify, test, or inspect products, designs, or installations for safety or health purposes. Any certification or other statemen
12、t of compliance with any health or safetyrelated information in this document shall not be attributable to NEMA and is solely the responsibility of the certifier or maker of the statement. DC 10-2009 Page i CONTENTS Forewordii History of Standardsiii Section 1 GENERAL.1 1.1 Scope1 1.2 References1 1.
13、3 Definitions.1 Section 2 RATINGS AND CLASSIFICATIONS3 2.1 Voltage Ratings.3 2.2 Current Ratings.3 2.3 Functional Classifications .3 2.3.1Linear-Sensing Type .3 2.3.2Spot-Sensing Type3 Section 3 CONSTRUCTION.4 3.1 Envelope Dimensions.4 3.1.1Linear-Sensing Type .4 3.1.2Spot-Sensing Type4 3.2 Mounting
14、 .4 3.2.1Linear-Sensing Type .4 3.2.2Spot-Sensing Type4 3.3 Connections4 3.3.1Terminals.4 3.3.2Wiring 4 3.4 Operating Mechanism.4 3.5 Enclosure 5 3.6 Corrosion Protection .5 3.7 Adjustments 5 Section 4 PERFORMANCE6 4.1 Cut-out Settings 6 4.2 Cut-in Settings.6 4.3 Determination of Cut-out and Cut-in
15、Temperatures .6 4.3.1Linear-Sensing-Type Controls 6 4.3.2Spot-Sensing-Type Controls.7 4.4 Endurance.7 Section 5 MARKING .8 5.1 Marking .8 Section 6 APPLICATION 9 6.1 Installation.9 6.2 Wiring9 6.2.1Spot-Sensing Type9 6.2.2Linear-Sensing Type .9 6.3 Instructions9 6.4 Spot-Type Control Systems9 Copyri
16、ght 2009 by the National Electrical Manufacturers Association. DC 10- 2009 Page ii Foreword This Standards Publication defines the basic standards for rating, classification, construction, testing, and performance of temperature limits controls for application on electric baseboard heaters. It has b
17、een developed in the public interest and is designed to promote a better understanding between the manufacturer and the user, where possible, to provide direct interchangeability through industry standardization, and to assist the user in selecting the proper controls for his or her particular appli
18、cation. These standards are periodically reviewed by the Residential Controls Section of NEMA for any revisions necessary to keep them up-to-date with advancing technology. Proposed or recommended revisions should be submitted to: Vice President, Technical Services National Electrical Manufacturers
19、Association 1300 North 17th Street, Suite 1752 Rosslyn, Virginia 22209 This Standards Publication was developed by the Residential Controls Section. Section approval of the standard does not necessarily imply that all Section members voted for its approval or participated in its development. At the
20、time it was approved, the group was composed of the following members: Apcom Inc.Franklin, TN Emerson Electric Company, White-Rodgers DivisionSt. Louis, MO GE Industrial SystemsMorrison, IL Honeywell, Inc.Golden Valley, MN Therm-O-DiscMansfield, OH Copyright 2009 by the National Electrical Manufactu
21、rers Association. DC 10-2009 Page iii History of Standards The Residential Controls Section of NEMA was formed in 1940 to promote the standardization of products within the scope of the Section. These product standards cover definitions, ratings, performance, testing, and dimensions. NEMA standards
22、are voluntary and are designed to eliminate misunderstandings between the purchaser and the manufacturer. This publication is one of a series sponsored by the Residential Controls Section. Other publications in this series are identified as Pub. No. DC XX (followed by the year of issue). The Technic
23、al Committee of the Residential Controls Section of NEMA first formed a subcommittee to develop temperature limit control standards for electric baseboard heaters in 1960. The deliberations of this committee resulted in the NEMA Standards Publication for Temperature Limit Controls for Electric Baseb
24、oard Heaters, DC 10-1964, which was later revised and superseded first by DC 10-1971, by DC 10-1977, and then by DC 10-1983. The present publication, DC 10-2009, is published in accordance with NEMAs policy of periodic review and revision to keep NEMA Standards contemporary with industry needs and t
25、echnological advancement. It revises the 1983 edition. Copyright 2009 by the National Electrical Manufacturers Association. DC 10- 2009 Page iv Copyright 2009 by the National Electrical Manufacturers Association. DC 10-2009 Page 1 Section 1 GENERAL 1.1 SCOPE This Standards Publication describes cons
26、tructional details, classifications, ratings, and other characteristics of temperature limit controls and control systems of the linear-sensing or spot types, which are suitable for mounting inside electric baseboard heaters for the purpose of disconnecting the electrical load when the heater reache
27、s abnormally high temperatures. The controls and control systems described in this Standards Publication are nonadjustable, operate at factory preset temperatures, and may be of the automatic- or manual-reset type. 1.2 REFERENCES The following normative documents contain provisions, which through re
28、ference in this text, constitute provisions of this Standards Publication. By reference herein these publications are adopted, in whole or in part as indicated, in this Standards Publication. Underwriters Laboratories Inc. 333 Pfingsten Road Northbrook, IL 60062 ANSI UL 873 Standard for Temperature-
29、Indicating and -Regulating Equipment 1.3 DEFINITIONS automatic-reset control: A control that opens and recloses the circuit automatically. cut-in temperature: The temperature in degrees C (degrees F) at which the circuit to the electrical load is restored automatically or can be restored by manual r
30、esetting action. cut-out temperature:The factory preset temperature in degrees C (degrees F) at which the control opens the circuit to the electrical load. cut-out temperature drift: The change in degrees C (degrees F) in the cut-out temperature as a result of a continuous cycling of the temperature
31、 limit control. differential: The difference between the cut-out and the cut-in temperatures. hot spot: The portion of the sensing element that causes the control to cut-out when it is subjected to the abnormally high temperature that it is intended to limit. It is stated in terms of a specific leng
32、th. (See Table 4-1.) load, electrical: The resistive noninductive controlled load expressed in volts and amperes or watts; or the inductive controlled load expressed in volts and amperes. manual-reset control: A control that opens the circuit automatically and is reclosed manually. pilot duty: A cla
33、ss of operation in which the ultimate electrical load is controlled by auxiliary means. rating, electrical: The maximum specified electrical load capability of the control. Copyright 2009 by the National Electrical Manufacturers Association. DC 10-2009 Page 2 sensing element:A continuous temperature
34、-sensing element of the control, generally mounted horizontally inside the baseboard heater in a protected location and in a manner that enables it to sense abnormally high temperatures. temperature limit controls: linear-sensing type: A control body and a sensing element no less than 355 mm (14 in.
35、) long, capable of sensing and reacting to temperature changes along its length. spot-sensing type: A control body with an integral sensing element capable of sensing and reacting to temperature changes at a particular location. Copyright 2009 by the National Electrical Manufacturers Association. DC
36、 10-2009 Page 3 Section 2 RATINGS AND CLASSIFICATIONS 2.1 VOLTAGE RATINGS Temperature limit controls shall have voltage ratings within the range of 120 to 600 volts, AC, inclusive. 2.2 CURRENT RATINGS Temperature limit controls shall have at least one of the following current ratings: Voltage Curren
37、t (V) Resistive (A) Pilot Duty (VA) 120 25 480 240 25 480 277 25 480 480 12.5 - 600 - 125 2.3 FUNCTIONAL CLASSIFICATIONS 2.3.1 Linear-Sensing Type A control that incorporates a linear sensing element that opens the control switch as a function of a hot spot at any point along the entire length of th
38、e sensing element. The sensing element is not connected into the electrical circuit. 2.3.2 Spot-Sensing Type A control having an integral sensing element that opens the control switch as a function of a hot spot at the control location. The sensing element may or may not be connected directly into t
39、he electrical circuit. Copyright 2009 by the National Electrical Manufacturers Association. DC 10-2009 Page 4 Section 3 CONSTRUCTION 3.1 ENVELOPE DIMENSIONS 3.1.1 Linear-Sensing Type The sensing element is generally a sensing tube (capillary) containing a temperature-sensing fluid. Generally, the ou
40、tside diameter of the tube-type sensing element does not exceed 3 mm (1/8 in.), and its length is no less than 355 mm (14 in.) and no more than 3,660 mm (12 ft). The control body is generally of such a size as to be suitable for mounting in a space of 57 mm (2 in.) deep behind the mounting face. 3.1
41、.2 Spot-Sensing Type These controls are generally tubular or round and are supplied with or without mounting means by the manufacturer. The envelope dimensions depend on the type of configuration but should be within 70 mm x 25 mm x 16 mm (2 in. x 1 in. x in.) 3.2 MOUNTING Temperature limit controls
42、 shall be suitable for mounting inside a baseboard heater. 3.2.1 Linear-Sensing Type Provision should be made for mounting the control with two No. 6 or No. 8 screws or equivalent means. The distance between the centerline of mounting holes should be 42 mm (1 in.) or 50 mm (2 in). 3.2.2 Spot-Sensing
43、 Type If mounting means are not provided by the control manufacturer, the user should securely mount the control(s) along the length of the baseboard heater. 3.3 CONNECTIONS 3.3.1 Terminals If terminals are provided, they shall be of a type that meets the requirements of Underwriters Laboratories In
44、c.s Safety Standard for Electrical Temperature-Indicating and -Regulating Equipment, UL 873. 3.3.2 Wiring If external wire leads are provided as a part of the control, the size of wire shall be in accordance with UL 873. 3.4 OPERATING MECHANISM 1. The limit control shall withstand without damage or
45、loss of calibration the effects of overriding temperature on the sensing element to the degree that may be anticipated for the expected service and as specified by the manufacturer. 2. A limit control, which is actuated by a change in the pressure of fluid confined in a self-contained bulb or capill
46、ary tube, shall be designed so that the control contacts assume the open position if the sensing element ruptures. Copyright 2009 by the National Electrical Manufacturers Association. DC 10-2009 Page 5 3. The manual-reset control shall operate on temperature rise to limit a temperature and to keep t
47、he circuit open until an operator mechanically resets the contacts. The reset mechanism shall be trip-free; that is, the construction shall be such that the contacts cannot be held in the closed position above the cut-out temperature regardless of the position of the resetting means. The reset mecha
48、nism may permit the control to automatically cycle and limit the temperature even with the reset button depressed. 3.5 ENCLOSURE An enclosure of insulating materials shall be of such thickness and so formed that it will protect operating parts against mechanical injury. Metallic parts, forming part
49、of the control enclosure, shall be of adequate strength and shall comply with the requirements of UL 873. 3.6 CORROSION PROTECTION Iron and steel parts (except in the case of bimetals, bearings, and so forth, where such protection is impracticable) shall be suitably protected against corrosion by enameling, galvanizing, sherardizing, plating, or other equivalent means. 3.7 ADJUSTMENTS Temperature limit controls shall be factory calibrated with a preset nonadjustable cut-out temperature. The means for calibration, if accessible or apparent, shall be modified