FORD EH1-1994 HEATING ELEMENTS OPERATED FROM LINE VOLTAGE《线路电压供电的发热元件》.pdf

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1、 Manufacturing StandardsFord Motor Company199409 HEATING ELEMENTS OPERATED FROM EH1LINE VOLTAGEEngineering Standards & Printed copies are uncontrolled.Systems Engineering (ESSE) Page 1 of 41. GENERAL:1.1 | SCOPE: The following standards apply to electric heating elements| used on industrial equipmen

2、t and operated from line voltage, 480| VAC.1.2 | APPLICATION: If the aggregate power required for the elements is| 2300 VA (5 amperes at 460 VAC) or more, they may be operated| directly from the 480 VAC line provided the elements, enclosures,| and wiring comply with this standard. When the total pow

3、er required| is less than 2300 VA, elements should be operated at 120 VAC and the| current obtained from the control transformer which supplies other| control devices on the equipment.2. | REFERENCE STANDARDS: Whenever a specific standard is mentioned in this| Standard, it is understood it will be t

4、he latest revision thereof unless| otherwise specified.2.1 | FORD MOTOR COMPANY:| Manufacturing Standards| ES20, “Disconnects and Operating Mechanisms“| EX1, “Electrical Standard For Mass Production Equipment“| Safety Technical Bulletins| Number 100, “Energy Control and Power Lockout Procedures“| Nu

5、mber 123, “Energy Control/Power Lockout Machinery and Equipment| Identification Guidelines“2.2 | INDUSTRY STANDARDS:| ISO 3864, “Safety Colours and Safety Signs“| UL 1030, “Sheathed Heating Elements“| NEMA 250, “Enclosures For Electrical Equipment (1000 Volts| Maximum)“3. REQUIREMENTS FOR ELEMENTS:3

6、.1 | The current carrying conductor of the element shall be embedded| inside, and insulated from, a grounded metal sheath. Elements shall| be UL Listed to the UL 1030 standard, or other appropriate UL and| CSA standards for the type involved.3.2 | Terminals on the element shall be rigid, self-suppor

7、ting, and| have phase-to-phase, and phase-to-ground insulation for 600 VAC.Manufacturing StandardsFord Motor Company199409 HEATING ELEMENTS OPERATED FROM EH1LINE VOLTAGEEngineering Standards & Printed copies are uncontrolled.Systems Engineering (ESSE) Page 2 of 43.3 TERMINAL ENCLOSURES:3.3.1 | Termi

8、nals on individual elements used for immersion heating,| platen heating, etc., shall be enclosed in a terminal box| preferably attached as an integral part of the element.| Threaded openings in trade sizes of 1/2 inch and larger shall| be provided in the box for conduit or fittings. Enclosures| shal

9、l be rated Type 12 or Type 13 in accordance with NEMA 250.3.3.2 | On multiple element installations, such as ovens and furnaces| where terminals are enclosed inside a trough or duct,| insulating barriers shall be installed around and over the| terminals to prevent accidental contact by personnel or|

10、 grounding of live parts to the metal enclosure. If plug and| jack quick disconnect assemblies are used on multiple| installations, they shall be approved by the specifying| activity.3.3.3 All terminal enclosures shall be grounded to the industrialequipment by means of bolts, threads, copper strap,

11、or otherapproved means.4. SERIES OPERATION:4.1 | Heating elements rated 230 VAC may be connected in series on 480| VAC if approved for such use by the element manufacturer. If| elements are so connected, all lines of the 480 VAC conductors shall| terminate in the same enclosure. The series connectio

12、ns between| elements may be made in the same enclosure or in one which meets the| requirements of section 3.3 above and located, if necessary, at| opposite ends of the elements.4.2 | Changes from series to parallel connections, or complete isolation| of elements to accomplish changes in temperature

13、output shall be| made by means of electromechanical or solid-state contactors. If| solid-state contactors are used, there shall be an electromechanical| contactor in series to open all the power conductors in accordance| with Standard EX1, section 6. One electromechanical contactor may be| used ahea

14、d of more than one solid-state contactor on equipment| having multiple temperature control zones.Manufacturing StandardsFord Motor Company199409 HEATING ELEMENTS OPERATED FROM EH1LINE VOLTAGEEngineering Standards & Printed copies are uncontrolled.Systems Engineering (ESSE) Page 3 of 44.2.1 | Equipme

15、nt using solid-state heater fuses, contactors, or| controllers shall be provided with load side fuses in each| phase supplying power to the heating elements. This facilitates| insulation resistance Megger testing of the heaters after fuses| are removed to isolate them. If approved in writing by the|

16、 specifying activity, controllers normally furnished with SCRs| and fuses in only two of three phases may be used, provided the| third phase is equipped with a removable copper bar for this| purpose. The copper bar shall be covered by a removable poly-| carbonate (Lexan or equal) shield to protect p

17、ersonnel from| accidental contact with live parts. Plexiglass, acrylic or| other potential combustion-supporting plastic materials shall| not be used for this purpose. This shield shall have the decal| and triangle warning symbol required under section 6 of this| Standard affixed to it in a clearly

18、visible manner.4.3 | DISCONNECTING MEANS: One “Main Electrical Disconnect“ shall be| provided and labeled as such on each piece of industrial equipment| in accordance with Standards ES20 and EX1 and with Ford Safety| Technical Bulletin Numbers 100 and 123. Where switches are remotely| located to con

19、trol individual heating units, they shall be Ford-| approved, NEMA Type 12 enclosures. If an auxiliary disconnect is| required to lock out machine motions, it shall be labeled as a| “Motion Disconnect“ on the machine and on the drawings, and shall be| powered from the load side of the Main Electrica

20、l Disconnect. Other| labels are to be provided for all disconnecting means per the Ford| safety technical bulletins.5. WIRING:5.1 | Wiring at potentials other than 480 VAC shall not terminate in, or| pass through, enclosures containing element terminals and| associated wiring.5.2 | Conductors connec

21、ted to heating elements shall be rated for| continuous operation at the design temperatures expected, including| worst case ambient temperature conditions. Conductors shall be| flexible stranded tinned copper, Type SF-2 or Type SR-ML, or as| otherwise specified.5.3 | Control devices for elements suc

22、h as thermostats, coils of| contactors, etc., shall operate at 120 VAC or a maximum of 240 VDC.| All provisions of Ford Manufacturing Standard EX1 shall be adhered| to wherever applicable.5.4 | All taped joints shall be covered with glass cloth tape which has| thermosetting adhesive.Manufacturing St

23、andardsFord Motor Company199409 HEATING ELEMENTS OPERATED FROM EH1LINE VOLTAGEEngineering Standards & Printed copies are uncontrolled.Systems Engineering (ESSE) Page 4 of 46. | IDENTIFICATION: Terminal boxes and enclosures containing connections to| or between heating elements shall be marked with a

24、 red, black, and white| decal which reads, “Danger 480 Volts.“ This decal shall be in addition| to any other decals such as those provided in accordance with symbol No.| 13 if ISO 3864 (black lightning flash on yellow background within a black| triangle).| NOTE - Denotes areas of change in previous issue.|