1、.() .Q 3 Southern Electrical Equipment Co., Charlotte, N. C. MEADOR, J. T. 2 Southern Electric Service Co., Charlotte, N. C. MEANS, W. A. Barber-Coleman Co., Rockford, 111. MESSNER, U. G. Micro Switch Div., Atlanta, Ga. PARKER, E. L. Westinghouse Electric Corp., Charlotte, N. C. PARKER, R. E., Secre
2、tary 1 General Electric Co., Charlotte, N. C. PONZER, J. L. Carolina Power therefore they are considered as Class III Hazardous Locations, as defined by the Na tional Electrical Code. The very minimum electrical installation requirements for such locations are out lined in Article 503, National Elec
3、trical Code. These requirements take precedence over those which apply in ordinary, non-hazardous locations. Equipment suit able for use in ordinary locations is generally not suit able for such textile processes. A few practices peculiar to the industry or of long standing either do not or cannot b
4、e made to conform to the National Electrical Code, for various reasons. Each such conflict is clearly identified and the recom mended practice is described. Where reference is made to a paragraph or section of the National Electrical Code, it is understood to mean the latest revision thereof. 10.6 A
5、pproved Equipment. The term “approved“ as used in this Recommended Practice refers to mate rial and equipment that is acceptable to the inspection authority having jurisdiction. Listing or labeling by Underwriters Laboratories, Inc., Factory Mutual Laboratories, or other nationally recognized testin
6、g agency is usually satisfactory evidence of acceptability. 11. DIAGRAMS AND EQUIPMENT IDENTIFICATION 11.1 Connection Diagrams. Connection diagrams showing panel wiring, line, load, and control connec tions with identifying numbering, shall be furnished with all equipment. The diagram shall, where p
7、racticable, be perma nently secured on the inside of the cover of the control enclosure. For special-purpose controllers the connection dia gram shall include an elementary diagram, and shall show connections to all related motors, control sta tions, limit switches and other auxiliary equipment. 11.
8、2 Equipment Identification. A permanent name-plate or other identification listing the manufacturers name, address, and identifying designation of the elec tric equipment shall be attached to the equipment. There shall also be provided identification of horse power, voltage, frequency, phase and cur
9、rent, and in the case of general-purpose controllers, the heater coil selection tables. 11.3 Renewal Parts Record. The electric equipment manufacturer and the machinery manufacturer should maintain records of the equipment throughout a rea sonable life expectancy, for purposes of furnishing renewal
10、parts and connection diagrams. 7 12. CONTROL CIRCUITS 12.1 Source of Control Power. The source of supply for all control circuits shall be taken from the load side of the principal or main disconnecting means. 12.2 Control Voltages 1. Control circuits at other than line voltage shall not be more tha
11、n 120 volts nominal. 2. Electric stop-motion equipment shall comply with the provisions of Section 20. 12.3 Interlocking. Where operation of control equipment in improper sequence can result in a hazard or damage, sequence interlocking or other effective safeguards shall be provided. Where two or mo
12、re controllers are to be electric ally interlocked, it shall be done with interlocks or relays so connected that there is no electric connection between the load side of one controller disconnecting device and the load side of the disconnecting device of another controller. 12.4 Undervoltage Protect
13、ion Circuits. Magnetic controllers and their associated pilot devices shall pro vide undervoltage protection, as outlined in paragraph 13.4. Group installation of manual loom starters require special considerations. See paragraphs 13.1.1 and 13.4.2. 13. OVERCURRENT AND UNDERVOLTAGE PROTECTION 13.1 M
14、otor Branch Circuit Overcurrent Protection. In general, motor branch circuits shall be protected against overcurrent in accordance with National Elec trical Code, sections 430-51 to 430-59 inclusive. Atten tion should be given to the following special require ments for textile application. 13.1.1 Gr
15、oup Fused Loom Motor Installations. Manual starters used to control single-motor looms, and where several loom motors are connected to one branch circuit shall be protected in accordance with National Electrical Code, paragraph 430-53. The manual starters with their motor-overload protective devices
16、 shall be approved for group fusing (i.e. approved for use with fuses larger than 400 percent of motor current rating. See National Electrical Code paragraph 430-40). Motor branch circuit fuses shall not have current ratings greater than those which will be found marked on the motor starter. All mot
17、or starters approved for “group fusing“ will have the maximum branch circuit fuse rating, indicated on the heater table inside of the starter enclosure. See Sections 25.4 and 25.5 for typical circuits. 13.2 Control Circuit Overcurrent Protection 13.2.1 Control Circuits Supplied Directly from Motor B
18、ranch Circuit. The conductors of control circuits at line voltage shall be protected against steady overloads and short circuits in accordance with National Electrical Code paragraphs 240-5 and 430-72. 13.2.2 Control Circuits Supplied through Control Transformer. The control-circuit transformer and
19、conductors shall be protected against secondary over loads and short circuits. Where the circuit is grounded, the protective device shall be located only in the ungrounded line. 13.2.3 Class 2 Lowvoltage Circuits. See Section 20. 13.3 Motor Running Overcurrent Protection 13.3.1 All continuous-duty m
20、otors shall be pro tected against overload by the use of devices respon sive to motor current, motor temperature, or both. Resetting of the overload device shall not restart the motor if restarting can cause injury to persons or damage to property. Where thermal protection integral with the motor is
21、 used and is of the type which leaves voltage on the motor terminals after tripping, arrangements shall be made to minimize possible shock hazard when servicing the motor. The number and location of such overload protec tive devices shall conform with National Electrical Code Sections 430-36 and 430
22、-37. 13.4 Undervoltage Protection 13.4.1 Undervoltage protection shall be provided for all equipment which can cause injury to persons or damage to property should a motion be initiated upon return of power after an undervoltage condi tion. 13.4.2 For group-fused installations, such as single-motor
23、looms protected in accordance with paragraph 13.1.1, the user shall install undervoltage protection. See Sections 25.4 and 25.5 for typical methods. 14. MOTOR-CONTROL EQUIPMENT 14.1 General. 14.1.1 All motor-control equipment shall conform with the latest issue of the National Electrical Manu factur
24、ers Association (NEMA) Standards for In dustrial Control; and shall be installed in accordance with the requirements of the National Electrical Code. 14.2 Alternating-Current Manual Starters. 14.2.1 The starter enclosure shall be gasketed, lint tight. There shall be no unused holes through the enclo
25、sure. If conduit knockouts are supplied they shall not be concentric or eccentric. The cover shall be held closed by captive fasteners. 8 14.2.2 External operating means shall be clearly marked to indicate handle position and operation. 14.2.3 The starter shall provide thermal-overload protection (p
26、referably trip free) unless equivalent protection is provided elsewhere. The term “trip free“ does not apply to manual reduced-voltage starters. 14.2.4 The manual motor starter shall be equipped with means for locking the external operating mech anism in the “off“ position unless an individual disco
27、nnecting means so equipped is provided for each motor starter. 14.3 Alternating-Current General-Purpose Single-Motor Magnetic Controllers. 14.3.1 A general-purpose single-motor magnetic starter or controller should be of the combination type, having a disconnecting device and a controller mounted in
28、 a common enclosure. The disconnecting device shall be externally operable, and mechanic ally interlocked so the enclosure door can be opened only when the disconnecting device is in the “off“ position. Means for locking the disconnecting device in the “off“ position shall be provided. The discon ne
29、cting device shall be a fusible motor-circuit switch or a circuit breaker. 14.3.2 The enclosure shall be NEMA Type 12. 14.3.3 The controller shall provide overload pro tection for the motor, preferably by means of a trip-free manually-reset thermal-overload relay. 14.4 Alternating-Current Special-Pu
30、rpose Magnetic Controllers. 14.4.1 For purposes of this Recommended Prac tice, an alternating-current special-purpose magnetic controller is any alternating-current multi-motor magnetic controller, or any alternating-current single-motor magnetic controller with special fea tures, such as an extra c
31、ontrol relay, designed for the particular type of textile machine with which it is to be used. 14.4.2 A special-purpose magnetic controller should be of the combination type, having a discon necting device and a controller in a common en closure. The disconnecting device shall be externally operable
32、 and mechanically interlocked so the enclos ure door can be opened only when the disconnecting device is in the “off“ position. Means for locking the disconnecting device in the “off“ position shall be provided. The disconnecting device shall be a fusible motor circuit switch or a circuit breaker. 1
33、4.4.3 The enclosure shall be NEMA Type 12. 14.4.4 The controller shall provide overload pro tection for each motor preferably by means of trip-free manually-reset thermal-overload relays. There shall be no external reset buttons for the overload relays. 14.4.5 Fixed terminals shall be provided for a
34、ll external connections. They shall be readily acces sible for making connections and plainly marked to correspond with the markings on the connection diagram. 14.4.6 The incoming power lines shall connect directly to the line side of the disconnecting means, with no connection to other terminals or
35、 other de vices ahead of the disconnecting means. 14.4.7 All control devices should be front-of-panel wired wherever front-connected components are available. 14.5 Direct-Current Constant-Voltage Controllers. See Section 23.1. 14.6 Direct-Current Adjustable-Voltage Controllers. See Section 23.2. 14.
36、7 Operators Control Station. 14.7.1 Pushbuttons and selector switches shall be of the NEMA Standard Duty or Heavy Duty elec trical rating suitable for the application. For “Stop-Motion“ see Section 20. 14.7.2 Control stations (including shipper rod operated master switches) shall have lint tight en
37、closures. NEMA 4 or NEMA 5 pushbutton stations, or oiltight pushbutton elements in gasketed lint-tight enclosures, are considered as meeting this re quirement. For “Stop-Motion“ see Section 20. 14.7.3 Pushbutton legends shall be clearly marked and located so they can be easily read by the opera tor.
38、 14.7.4 “Stop“ pushbuttons shall be identified by red color. 14.7.5 Control stations shall be located within easy reach of the operator and shall be so placed that the operator does not have to reach past moving parts that might cause injury. 14.8 Limit Switches. 14.8.1 Limit switches shall have lin
39、t-tight enclo sures. For “Stop-Motion“ see Section 20. 15. ENCLOSURES (FOR EQUIPMENT USED ON OTHER THAN “STOP-MOTION“) 15.1 General. For the purpose of this Recommended Practice, the word “enclosure“ means the housing for bare live parts including switches, motor controllers, circuit breakers and fu
40、ses, whether mounted upon, within or separate from the textile machine. A “com partment“ is an “enclosure“ built as a part of the textile machine. 9 15.2 Sparking or Bare Live Parts. Switches, circuit breakers, motor controllers (except manual loom motor starters) and fuses, including pushbuttons, r
41、elays and similar devices which may produce sparks or have bare live parts, shall be housed in NEMA Type 12 or equiv alent enclosures. Pushbuttons, limit switches and other small devices when housed in NEMA Type 4 or 5 enclosures, or which employ oiltight construction in lint-tight enclosures, are c
42、onsidered as meeting these requirements. Note: Manual loom motor starters shall have oil-resistant synthetic gaskets and shall be lint-tight, with no unused holes in the en closure. If conduit knockouts are supplied they shall not be con centric or eccentric. Covers shall be held closed by captive f
43、asteners. 15.3 Standard Textile Enclosure. The NEMA Type 12 Enclosure (Industrial-Use Enclosure) (IC. 1-2.70, paragraph H January 13, 1963) is considered the stand ard textile enclosure and is currently described as fol lows: “A Type 12 enclosure (Industrial-Use Enclosure) shall meet the following r
44、equirements: 1. When supplied for a combination-type controller, it shall include the following design features: a. It shall have an oil-resistant synthetic gasket between the case and the cover. b. The cover shall be hinged to swing horizon tally and shall be held in place with screws, bolts, or ot
45、her suitable fasteners which require the use of a tool, such as a screwdriver or wrench, to release. The fastener parts shall be captive so that they will not become lost when the cover is opened. There shall be no holes through the enclosure for mounting, or for mounting controls within the enclosu
46、re, and no conduit knockouts or conduit openings. c. External mounting feet or other suitable mounting means shall be provided. 2. When supplied for a non-combination-type con troller, it shall include the following design fea tures: a. It shall have an oil-resistant synthetic gasket between the cas
47、e and the cover. b. The cover fastener parts shall be captive so that they will not become lost when the cover is opened or removed. c. There shall be no unused holes through the enclosure for mounting controls within the en closure, and no conduit knockouts or conduit openings.“ 15.4 Control Equipm
48、ent. Control equipment shall be enclosed, and mounted in such a manner and posi tion as to guard it against physical abuse, and direct contact with combustible materials. If the control equipment is mounted in a compartment of the textile machine, the compartment shall be in a readily acces sible lo
49、cation, and shall provide an enclosure construc tion conforming with NEMA Type 12. 15.5 Material for Enclosure or Compartment. Ma terial employed for enclosure or compartment con struction shall conform to latest requirements of NEMA Industrial Control Standards, paragraph IC 1-2.72 February 1963 EnclosuresMaterial Require ments, paragraphs A, B, C, D, and E. 15.6 Enclosures for Heat-Producing Devices. Re sistors, coils, electron tubes and similar heat-producing devices shall be housed in enclosures so designed that surface temperatures will not exceed 90C maximum at rated load. (The
