1、 Printed copies are uncontrolled. Page 1 of 8 Standard Number: w-ES20 Issue Date: 20030217 Global Manufacturing Standards Rev: 20030220 DISCONNECT SWITCHES AND OPERATING MECHANISMS 1 PURPOSE AND SCOPE: This Standard applies to disconnects and operating mechanisms used in combination motor starters a
2、nd industrial control enclosures at 600 VAC and below. It also applies to separately mounted self-enclosed safety switches used for service disconnects and auxiliary equipment. This Standard does not apply to 480 VAC power distribution equipment, such as unit substations and busways. 1.1 MANDATORY A
3、ND 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“. 1.2 DEFINITIONS: 1.2.1 DISCONNECT (Disconnecting Means): A disconnect switch, circuit breaker, automatic molded case switch
4、(MCS), or safety switch used as an energy isolating device on industrial equipment in accordance with 29 CFR 1910.147. The disconnect shall isolate the equipment from all ungrounded conductors of the supply circuit and shall be capable of being locked out with at least 3 standard Ford-issued padlock
5、s, refer to Section 6.7. 1.2.2 OPERATING MECHANISM: The external handle, linkage, and coupling mechanism to the disconnect. 1.2.3 EXTERNAL HANDLE: That portion of the operating mechanism that is mounted on the right-most enclosure flange for main disconnect switches, or to the front of the switch en
6、closure for IEC rotary switches (see Clause 3.5). 1.2.4 LINKAGE: The connection between the external handle and the coupling mechanism. 1.2.5 COUPLING MECHANISM: The device which operates the disconnect to the ON and OFF positions. 1.2.6 AUTOMATIC MOLDED CASE SWITCH (MCS): An enclosed switching devi
7、ce which looks like a circuit breaker, but that contains a nonadjustable, magnetic instantaneous trip unit providing only short-circuit protection. 1.2.7 CURRENT LIMITING CIRCUIT BREAKER: An enclosed thermal magnetic switching device that does not employ a fusible element and that when operating wit
8、hin its current-limiting range: Printed copies are uncontrolled. Page 2 of 8 Standard Number: w-ES20 Issue Date: 20030217 Global Manufacturing Standards Rev: 20030220 1.2.7.1 Limits the let-through I2t current to a value less than the I2t current of the first half cycle wave of the symmetrical prosp
9、ective current. 1.2.7.2 Interrupts before the current peak and clears the fault completely within the first half cycle. 1.2.8 IEC DISCONNECT: An IEC designed manual motor controller/isolator (load break switch) additionally marked “Suitable As Motor Disconnect“. 2. NORMATIVE REFERENCES: Disconnects
10、shall conform to the latest revisions of the following standards, except where noted. Where differences exist this standard shall take precedence. SAE HS-1738 (1995) Electrical Standard for Industrial Machinery IEC/EN 60204-1 Safety of Machinery Electrical Equipment of Machines, Part 1. General Requ
11、irements ANSI/NFPA 70 - National Electrical Code (N.E.C.) Knife Blade Type Disconnect Switches: National Electrical Manufacturers Association (NEMA) KS-1 “Enclosed Switches“. Underwriters Laboratories (UL) ANSI/UL 0098 “Enclosed and Dead-Front Switches“. Canadian Standards Association (CSA) C22.2.4,
12、 “Enclosed Switches“. Rotary Type Disconnect Switches: Underwriters Laboratories (UL) ANSI/UL 508 “Industrial Control Equipment“. Canadian Standards Association (CSA) C22.2.14, “Industrial Control Equipment“. IEC 60947-3 “Low Voltage Switchgear and Controlgear Part 3: Switches, Disconnectors, Switch
13、-Disconnectors, and Fuse-Combination Units“. Circuit Breakers and Molded Case Switches: National Electrical Manufacturers Association (NEMA) AB-1, “Molded Case Circuit Breakers and Switches“. Underwriters Laboratories (UL) ANSI/UL 498, “Molded Case Circuit Breakers and Circuit Breaker Enclosures“. U
14、nderwriters Laboratories (UL) ANSI/UL 1087, “Molded Case Switches“. Canadian Standards Association (CSA) C22.2.5, “Molded Case Circuit Breakers, Molded Case Switches, and Circuit Breaker Enclosures“. 2.1 All disconnecting means shall be UL Listed, CSA Certified, and CE Marked in accordance with the
15、above standards and shall bear these mark(s). Printed copies are uncontrolled. Page 3 of 8 Standard Number: w-ES20 Issue Date: 20030217 Global Manufacturing Standards Rev: 20030220 Note: Safety disconnect switches are either UL Listed or CSA Certified. This is due to differences in requirements for
16、bonding the neutral bar inside the switch enclosure. 3. GENERAL REQUIREMENTS ALL TYPES: 3.1 DISCONNECT SWITCHES shall have visible knife blades OR positive-opening contacts. Both types shall have durable handle position markings that indicate all switch contacts are open in the OFF or “0“ position.
17、3.2 CIRCUIT BREAKERS and MOLDED CASE SWITCHES (MCS) 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 NEMA and IEC requirements for its maximum voltage rating. 3.3 SAFETY SWITCHE
18、S shall have NEMA 12 (or minimum IP54) “Heavy Duty“ steel enclosures without knockouts, unless otherwise specified by the requisitioning activity. 3.4 AUXILIARY CONTACTS: N.O./N.C. interlock contact kits, either single or dual, shall be available from the disconnect switch manufacturer. These interl
19、ocks shall open their contact(s) slightly before the disconnect opens. 3.5 OPERATING HANDLE SHALL BE PERMANENTLY AFFIXED to the disconnect so the HANDLE IS IN CONTROL OF THE DISCONNECT AT ALL TIMES, including when the enclosure door(s) are open. This requirement does not preclude removal of the hand
20、le or enclosure cover with tools. 3.6 TERMINAL CONNECTIONS: 3.6.1 Protection: There shall be no exposed live parts when the disconnect is in the OFF (open) position. An insulating cover, shield, or other means shall be provided by the disconnect manufacturer to guard against inadvertent contact with
21、 the line terminals. If test probe holes are provided in this cover, they shall be designed with an IP2X finger-safe rating, and prevent shorting between live parts or live parts and other metal parts. 3.6.2 Terminal Connectors: Connectors shall be pressure screw type for suitable for copper wire an
22、d in conform to UL 98 Section 11.3. Terminals for #8 AWG (10 mm2) or smaller conductors shall be the pressure plate type. 3.7 SUPPLEMENTARY SHIELDS: The Standards listed under the Normative References do not require shields over fusible disconnects. Where local government regulations or Ford Divisio
23、n-level specifications dictate shields, they shall be provided only by the disconnect manufacturer in order to maintain the UL/CSA/CE safety rating of the disconnect. Printed copies are uncontrolled. Page 4 of 8 Standard Number: w-ES20 Issue Date: 20030217 Global Manufacturing Standards Rev: 2003022
24、0 3.8 GROUNDING PROVISIONS: Shall conform to UL 98 Section 16 and Section 17. 3.9 CORROSION PROTECTION: Shall conform to UL 98 Section 7.10 and Section 7.11. 4. DISCONNECTS: Unless otherwise specified by the requisitioning activity, a fusible disconnect switch (Figure A) shall be used where the tota
25、l rated load is 200 Amps or less. For rated loads of greater than 200 Amps, either a Molded Case Switch (MCS) with a trailing set of current-limiting Type II fuses (Figure B) or a Current Limiting Circuit Breaker with Type II branch fuse protection (Figure C) shall be used. Note: Fuse sizes and numb
26、er of branch circuits are for example only. TO CURRENT LIMITING TYPE II BRANCH FUSES (EX: J-Class or CC-Class)NOTE: DO NOT WIRE DIRECTLY TO MOTOR CONTROLDEVICES WITHOUT THE ABOVE BRANCH FUSES.4.1 Circuit breakers and Molded Case Switches (MCS) shall be selected and applied so their specified interru
27、pting rating exceeds the short-circuit current available at the rated voltage for their application. 5. ROTARY DISCONNECTS: 5.1 Rotary disconnects shall not be used, except as follows: 5.1.1 Rotary disconnects which are an integral part of Ford-approved, UL Listed, CSA Certified, and CE marked trans
28、former/disconnect assemblies (refer to Ford Global Manufacturing Standard w-EW3). 5.1.2 Rotary IEC disconnects that conform to Clauses 1.2.8, 2, and 2.1 of this Standard may be used as field service switches on motors in conformance with NFPA 70 (NEC), Article 430-109(a)(6). Printed copies are uncon
29、trolled. Page 5 of 8 Standard Number: w-ES20 Issue Date: 20030217 Global Manufacturing Standards Rev: 20030220 5.1.3 Rotary IEC disconnects which are main disconnects on individual 120 VAC “Lean Cell“ machines with finger-safe controls, and where the power cables to the individual machines are provi
30、ded with readily accessible overcurrent protection devices at their point of supply. 5.1.4 Rotary IEC disconnects that are part of “Off-the-Shelf“ Equipment operating at 150 VAC or greater, that involves no custom engineering, and cannot practically be furnished with a flange-mounted disconnect, sha
31、ll meet the following supplemental requirements: 5.1.4.1 A knife-blade safety switch that conforms to this Standard and Ford Global Manufacturing Standard EX-1 shall be mounted to the outside of the control enclosure as the new “main disconnect“. 5.1.4.2 This external “main disconnect“ shall be inst
32、alled between the power source and the line side of the rotary disconnect means inside the control enclosure of the equipment. 5.1.4.3 ECPL placards and required labels shall identify this new external main disconnect as the “Main Electrical Disconnect (E1)“ while the rotary disconnect means within
33、the control enclosure of the equipment shall be designated as “(E)“. 5.1.4.4 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 by the ANSI/NFPA 79. 6. OPERATING MECHANISMS shall con
34、form to UL 98 Section 7 and the following: 6.1 YOKE: Yokes for knife blade switches, circuit breakers or MCS shall be the “full-bail“ type. Full-bail mechanisms shall be attached to pivot points on both sides of the disconnect. 6.1.1 Exception: “Half-bail“ mechanisms are acceptable for use on circui
35、t breakers or MCS as approved by the Ford Global Manufacturing Standards Electrical Technical Committee. The criteria for this acceptance shall be the toggle operating force and the robustness of the design, including mechanical strength and retention of fasteners. 6.2 LINKAGE: The linkage shall be
36、either a solid rod or bar or a sheathed aircraft cable provided by the disconnect manufacturer. 6.2.1 Cable linkages shall be fixed in length by the disconnect manufacturer and shall not be user or field adjustable. Printed copies are uncontrolled. Page 6 of 8 Standard Number: w-ES20 Issue Date: 200
37、30217 Global Manufacturing Standards Rev: 20030220 6.3 MOUNTING PROVISIONS: The disconnect switch, circuit breaker, or molded case switch (MCS) shall be fastened to its own rigid metal mounting plate or shall otherwise consist of a single piece assembly. This assembly shall be mountable directly to
38、the control panel. Designs shall assure rigidity and positive alignment between the operating mechanism and the disconnect. Mounting of the disconnect on standoffs or brackets is not acceptable. 6.4 VARIABLE-DEPTH TYPE DISCONNECTS shall be the only operating mechanism acceptable for main disconnects
39、. 6.4.1 FIXED-DEPTH TYPE DISCONNECTS shall NOT be accepted. 6.5 FLANGE-MOUNTED HANDLES shall not be mounted on a door, a mullion, or an enclosure side-wall. 6.5.1 The handle shall operate in a vertical plane, with the ON position being up, and the OFF position (and reset if applicable) being down an
40、d shall conform to UL 98 Clause 6.5.1. 6.5.2 Handles made of conducting material shall be grounded to the enclosure and shall conform to UL 98 Clause 7.3. 6.5.3 Escutcheon plates, embossed letters, or other suitable means shall be provided to clearly indicate operating handle positions with the word
41、s: “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. 6.5.4 Handles shall be mounted to the enclosure with means that do not compromise the NEMA or IP ra
42、ting of the enclosure. 6.5.5 Finger clearance shall be provided between the operating handle and the enclosure surface in the ON, OFF, and if applicable, the RESET positions. The operating handle shall remain against the backstop in the ON position. 6.6 CIRCUIT BREAKER AND MOLDED CASE (MCS) DISCONNE
43、CTS: The operating handle shall have sufficient overtravel in the OFF direction to provide a distinct RESET position beyond OFF (open). Solid rod or bar type linkages shall be easily adjusted to provide proper opening and closing action the disconnect and shall not become misadjusted despite repeate
44、d operations. Any misadjustment in the linkage which interferes with the reliable opening of all disconnect contacts shall also act to prevent the reclosure of the disconnect once the operating handle is placed in the OFF position. Printed copies are uncontrolled. Page 7 of 8 Standard Number: w-ES20
45、 Issue Date: 20030217 Global Manufacturing Standards Rev: 20030220 6.7 LOCKABLE ONLY IN THE “OFF“ POSITION: The operating handle mechanism on all types of of disconnects shall be lockable only in the “OFF“ (open) position, with a minimum of three locks as described in Clause 6.7.2 It shall not be po
46、ssible to force the disconnect to the ON position while it is locked OFF. 6.7.1 Safety switches used with fire detection or protection systems shall have a user-modifiable provision for locking in the ON position. 6.7.2 Locks shall have shackles not larger than 5/16 inch (8mm) in diameter and a shac
47、kle clearance of at least 2.0 inches (5cm) measured from the top of the lock body to the inside diameter of the shackle. 7. DOOR-TO-DISCONNECT MECHANICAL INTERLOCKS: A mechanical interlock shall be provided so the door adjacent to the disconnect handle can be opened only when the disconnect is in th
48、e OFF position. A means to bypass this interlock shall be provided and shall operate as described in Clauses 7.1 and 7.2. 7.1 The bypass shall require the use of a screwdriver or 7mm square key to open the door(s) with the disconnect in the ON position. This interlock shall be reactivated automatica
49、lly 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 associated with the external handle is manually operated. 7.2 TWO-STEP BYPASS: When the disconnect switch, circuit breaker, or molded case switch (MCS) is mounted within an enclosure, it shall be necessary to open the door to the initial latch position with its vault handle by using a screwdriver (or 7mm square key, if specified) before the interlock on the external disconnect handle will be allowed to fully release the door. 7.
