FORD ES20-1995 DISCONNECTS AND OPERATING MECHANISMS AND SAFETY SWITCHES《断开和操作机制和安全开关》.pdf

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1、FORD MANUFACTURING STANDARDS ES20 DISCONNECTS AND OPERATING MECHANISMS ES20 SEPTEMBER 1995 AND SAFETY SWITCHES Page 1 1. SCOPE: 1.1 1.2 1.2.1 1.2.2 1.2.3 1.2.4 1.2.5 1.3 1.3.1 This Standard applies to disconnects and operating mechanisms used in combination motor starters and industrial equipment en

2、closures at 600 Vat and below. It also applies to separately mounted safety switches used for service disconnects and on auxiliary equipment. DEFINITIONS APPLICABLE TO THIS STANDARD: The DISCONNECT is any disconnect switch, circuit breaker, fusible molded case switch (FMCS), or safety switch applied

3、 as the means of disconnecting the industrial equipment from the electrical power source(s). The OPERATING MECHANISM includes the external handle, linkage, and yoke or other coupling to the disconnect. The EXTERNAL HANDLE is that portion of the operating mechanism mounted on the enclosure flange or

4、to the right side of the enclosure for safety switches. The LINKAGE is the mechanical connection between the external handle and the yoke or coupling. The YOKE or COUPLING is the device which operates the disconnect. REFERENCE STANDARDS: Devices furnished under this standard shall conform with the l

5、atest revisions of the following standards, except where differences exist this standard shall.take precedence. Ford Manufacturing Standard EKl and EK3 ANSI/NFPA 70, “National Electrical Code“, (N.E.C.) National Electrical Manufacturers Association (NEMA) AB-1, “Molded Case Circuit Breakers and Swit

6、ches.“ Nema KS-l, “Enclosed Switches,“ (Type HD) HEAVY DUTY. Underwriters Laboratories (UL) 98, “Enclosed and Dead-Front Switches.“ UL 489, “Molded Case Circuit Breakers and . Circuit-Breaker Enclosures.“ UL 508, “Industrial Control Equipment.“ UL 1087, “Molded Case Switches.“ All disconnects shall

7、be UL listed for use in USA and/or CSA certified for use in Canada in accordance with the above standards and shall bear the mark(s) of these agencies. FORD MANUFACTURING STANDARDS - ES20 DISCONNECTS AND OPERATING MECHANISMS SEPTEMBER 1995 AND SAFETY SWITCHES ES20 Page 2 2.3.1 2.3.2 1.4 2. 2.1 2.2 2

8、.3 MANDATORY AND PREFERRED ITEMS: Mandatory requirements of this Standard are characterized by the use of the word “shall.“ Preferred items are characterized by the use of the word “should.“ ROTARY DISCONNECT OPERATORS ARE NOT ACCEPTABLE, unless they conform with all the requirements of this standar

9、d. EXCEPTION: Switches which are an integral part of Ford-approved, UL listed transformer/disconnect assemblies up to 3.0 KVA are excepted, (refer to Ford Standard EW3). Rotary disconnects having permanently affixed handles operating through either a gasketed hole in the enclosure door or through th

10、e side of the enclosure shall not be used, unless they conform to this standard and Ford Standard EKl, and have been accepted in writing by Ford Controls Engineering and Safety Engineering as part of the bid submitted by the equipment seller. LOCKOUT OF MOTION OR OTHER HAZARDS: Transformer/disconnec

11、t assemblies shall not be used as power sources for equipment motions or other hazards - unless these hazards are capable of being de-energized and locked out with other disconnects meeting this standard - in strict accordance with Ford Energy Control and Power Lockout (ECPL) policies and procedures

12、. NOTE: The plug on cord-and-plug connected equipment is considered a disconnect if it is capable of being removed from its receptacle to isolate the equipment from its power source and the plug can be locked out. Other equipment may require its own knife-blade safety switch. SUPPLEMENTAL REQUIREMEN

13、TS FOR OFF-THE-SHELF EQUIPMENT: Where commercially available, “off-the-shelf“ equipment, which involves no custom engineering, cannot practicably be furnished with flange- mounted disconnects, it shall be equipped with a disconnect which fully conforms to this standard and Standard Exl. This will ty

14、pically be a NEMA 12, knife-blade safety switch mounted to the outside of the main electrical enclosure. This primary disconnect shall be installed between the power source and the line side of whatever disconnecting means is furnished within the electrical enclosure of the equipment. ECPL placards

15、and required labels shall identify this primary safety switch or disconnect as the “Main Electrical Disconnect (El)“ while the disconnecting means furnished within the enclosure of the equipment shall be designated as “(E2).“ FORD MANUFACTURING STANDARDS ES20 DISCONNECTS AND OPERATING MECHANISMS ES2

16、0 SEPTEMBER 1995 AND SAFETY SWITCHES Page 3 2.4 2.5 3. 3.1 In all cases, the disconnecting means furnished inside the enclosure of the “off-the-shelf“ equipment shall provide the mechanical door-to-disconnect interlock required under this standard and Ford Standard EXl. Self-enclosed, rotary switche

17、s are not acceptable as substitutes for Ford-approved, knife-blade safety switches which conform to this standard. PREFERRED DISCONNECTS: Unless otherwise specified by the requisitioning activity, a fusible disconnect switch is preferred where the total load is less than 200 Amps. For loads of 200 A

18、mps and more a circuit breaker or (FMCS) is preferred. Circuit breakers shall be selected and applied so their UL listed interrupting rating exceeds the short-circuit current available at their line terminals at the supply voltage. Circuit breakers fed directly from substations will generally requir

19、e higher interrupting ratings than those fed from fusible switches or busplugs containing Ford-approved, current-limiting power fuses. 4. DISCONNECT REQUIREMENTS: 4.1 Switches shall have knife blades or movable contacts which provide readily visible, positive indication of being open in the OFF posi

20、tion. 4.2 Switches shall be rated in.both Amperes and horsepower. 4.3 Circuit breakers or (FMCS) shall have a position indicator which cannot indicate OFF until all contacts are actually open with an adequate isolating distance between the contacts in conformance with NRMA and NFPA 70 requirements f

21、or the maximum voltage rating involved. 4.4 Safety switches shall have NEMA 12 enclosures unless otherwise required by their operating environment. Types without knockouts should be specified. 4.4.1 Auxiliary Contacts: UL listed, N.O./N.C. electrical interlock kits shall be available for safety swit

22、ches from approved manufacturers. These interlocks shall open their contact(s) slightly before the safety switch opens. FOR0 MANUFACTURING STANDARDS ES20 DISCONNECTS AND OPERATING MECHANISMS SEPTEMBER 1995 AND SAFETY SWITCHES ES20 Page 4 4.5 OPERATING HANDLE PERMANENTLY AFFIXED: The operating handle

23、 shall be permanently affixed to the disconnecting means. The linkage shall be a solid rod or bar and SHALL BE SUCH THAT THE OPERATING HANDLE IS IN CONTROL OF THE DISCONNECT AT ALL TIMES, including when the door(s) is/are open. 5. GENERAL REQUIREMENTS: 5.1 CONDUCTOR TERMINATION: 5.1.1 Protection: Th

24、ere shall be no exposed live parts in the OFF (open) position. An insulating cover or shield or other means shall be provided by the disconnect manufacturer as a component part of their UL listed assembly to guard against inadvertent contact with the line terminals. Where provided, test prod access

25、holes in this cover shall be insulated to prevent shorting between terminals or between a terminal and any non current-carrying metal parts. 5.1.2 5.1.3 5.2 5.3 Terminal Connectors: Terminal connectors and other current carrying parts shall be of copper or copper alloys. Connectors furnished with th

26、e disconnect, or available separately in kit form, shall be the pressure screw type suitable for connecting stranded copper bus drop cable or type MTW, THHN or THWN conductors. Neither the head nor the point of the screw shall bear directly on conductor strands when terminating AWG size 8 and smalle

27、r conductors. Minimum distance between line and load terminals, center to center, shall be three inches. Preferred arrangement is with line terminals above, and load terminals below the disconnect. SHIELDS: Supplemental shields over the disconnect, if and when required by government safety regulatio

28、ns, shall be furnished only by the disconnect manufacturer. UL listing and/or CSA certification of the disconnect assembly shall be maintained with such shields in place. GROUNDING PROVISIONS: A screw or lug shall be provided inside safety switches to serve as a ground wire termination point and for

29、 bonding the metal enclosure to ground. The screw or lug shall be colored green or otherwise marked with an N.E.C. acceptable ground symbol. 5.4 CORROSION PROTECTION: Metal parts shall be non-corrosive or otherwise treated to resist the effects of corrosion and oxidation. FORD MANUFACTURING STANDARD

30、S ES20 SEPTEMBER 1995 DISCONNECTS AND OPERATING MECHANISMS AND SAFETY SWITCHES ES20 Page 5 6. OPERATING MECHANISMS: 6.1 GENERAL: 6.1.1 YORE OR COUPLING: Yokes for disconnect switches, circuit breakers or (FMCS) shall be the full-bail type. Operating mechanisms for safety switches should be the direc

31、t-to-handle coupled, through-rod type. Both types of devices shall be attached to pivot points on both sides of the switch or the disCOMeCtS own mounting plate. 6.1.2 6.1.3 6.1.4 6.1.5 MOUNTING PROVISIONS: The disconnect switch, circuit breaker or (FMCS) shall be fastened to its own rigid metal moun

32、ting plate or shall otherwise consist of a single piece assembly. This assembly shall be mountable directly to the control panel. Designs shall assure rigidity and positive alignment between the operating mechanism and the disconnect. VARIABLE-DEPTH TYPE DISCONNECTS: Only variable-depth disconnect o

33、perating mechanisms shall be acceptable. The linkage between the external handle and the yoke shall be suitable for enclosures up to 19 inches in depth, to allow mounting the disconnect directly on the panel. Mounting of the disconnect on standoffs or brackets is not acceptable. An adjustable steel

34、brace should be between the handle assembly and the the disconnect. provided for support backplate which supports Screws required for mounting or joining components of the handle, linkage, and yoke or coupling shall be hex head or hexagon socket types and furnished with the assembly. Where a single

35、screw is used for joining parts, the parts shall be designed so the screw does not act as a pivot or allow movement or rotation of the parts joined. 6.2 FLANGE-MOUNTED HANDLES: The external handle for operating the mechanism shall not be mounted on a door; mounting on a mullion between doors is not

36、recommended. The handle shall be designed for field mounting and types shall be available for mounting on both. left and right hand flanges of multiple door enclosures. 6.2.1 The handle shall operate in a vertical plane, the ON position being up, and the OFF position (and reset if applicable) being

37、down. FORD MANUFACTURING STANDARDS .- ES20 DISCONNECTS AND OPERATING MECHANISMS SEPTEMBER 1995 AND SAFETY SWITCHES ES20 Page 6 6.2.2 The handle shall be made of metal and grounded to the enclosure. 6.2.3 Escutcheon plates or other suitable means shall be provided to clearly indicate operating handle

38、 positions with the words: “ON“ and “OFF.“ If color is used, the ON position shall be red and OFF shall be black. Solid plastic or similar material should be used for colored knobs or handle inserts; paint is not acceptable. 6.2.4 6.2.5 6.2.6 6.2.7 An oil resistant, synthetic material gasket shall b

39、e provided between the handle assembly and enclosure surface to comply with NEMA 12 requirements. Paper and cork materials are not acceptable. Finger clearance shall be provided between the operating handle and the enclosure surface in the ON, OFF, and if applicable, the RESET positions. The operati

40、ng handle shall remain against the backstop in the ON position. CIRCUIT BREAKER (AND FMCS) DISCONNECTS: Movement of the flange-mounted operating handle to the OFF position shall guarantee the opening of all contacts on the disconnect. The operating handle shall also have sufficient overtravel in the

41、 OFF direction to provide a distinct RESET position beyond OFF (open). The linkage shall be easily adjusted to provide proper opening and closing action of the disconnect and shall not become misaligned or misadjusted despite repeated operations. Any misadjustment in the linkage which prevents the r

42、eliable opening of all contacts shall also act to prevent the reclosure of the disconnect once the operating handle is placed in the OFF position. LOCKABLE ONLY IN THE “OFF“ POSITION: The operating handle mechanism shall be lockable only in the “OFF“ (open) position, with a minimum of three locks as

43、 described in 6.2.8. It shall not be possible to force the disconnect to the ON position while it is locked OFF. NOTE: Safety switches used with fire detection or protection systems shall have a user-modifiable provision for locking in the ON position. This modification shall only be performed by th

44、e requisitioning activity and consists of drilling out a center-punched dent or other specific item provided by the switch manufacturer at the proper location for applying the lock. FORD MANUFACTURING STANDARDS ES20 DISCONNECTS AND OPERATING MECHANISMS SEPTEMBER 1995 AND SAFETY SWITCHES ES20 Page 7

45、6.2.8 Locks shall have shackles not larger than 5/16 inch in diameter and a shackle clearance of at least 2.0 inches measured from the lock body to the inside diameter of the shackle. 6.2.9 The manufacturer of the operating mechanism shall furnish mounting dimensions and instructions for assembly. 7

46、. MECHANICAL INTERLOCKS: 7.1 DOOR-TO-DISCONNECT INTERLOCK: 7.1.1 A mechanical interlock shall be provided so the door adjacent to the disconnect handle can normally be opened only when the disconnect is in the OFF position. A means to bypass the interlock shall be provided. The bypass shall require

47、the use of a screwdriver to permit opening the door(s) with the disconnect in the ON position. The interlock shall be reactivated automatically when the door is closed to the initial latch position. When the door is open, it shall not be possible to close the disconnect unless the interlock on the e

48、xternal handle is manually operated. TWO-STEP BYPASS: When the disconnect switch, circuit breaker or (FMCS) is mounted within an enclosure, it shall be necessary to first open the door to the initial latch position with its vault handle by using a screwdriver (or key, if specified) before the interl

49、ock on the external disconnect handle will be allowed to fully release the door. 7.1.2 7.1.3 Approved manufacturers shall also provide door interlocking vault hardware to operate in conjunction with their disconnects. Provision shall be made to mechanically interlock two or more disconnects mounted in the same enclosure so that all power must be “OFF“ prior to opening the door(s). FORD MANUFACTURING STANDARDS ES20 DISCONNECTS AND OPERATING MECHANISMS SEPTEMBER 1995 AND SAFETY SWITCHES ES20 Page 8 . 8. PERFORMANCE REQUIREMENTS: 8.1 RELIABILITY: The handle mechanism shall be tested for a min