FORD EFX-1994 POWER FACTOR CORRECTION《功率因数校正》.pdf

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1、FORD MANUFACTURING STANDARDS = EFX POWER FACTOR CORRECTION EFX JUNE 1994 Page 1 = 1. SCOPE: 1.1 This Standard prescribes the application of power factor correction capacitors to individual as well as groups of electric motors used on production machines and equipment. 1.2 Capacitors, enclosures, wir

2、ing, and installation shall conform as applicable to this Standard and the following: A. Ford Manufacturing Standard, EXl, “Electrical Standard for Mass Production Equipment“. B. Ford Manufacturing Standard, EMl, “AC Electric Motors, Totally -Enclosed Type“. C. Ford Manufacturing Standard, EMlX, “AC

3、 Electric Motors, Totally- Enclosed Design and Reference Data“. D. ANSI/NFPA 70, “National Electrical Cadet (NEC), Article 460, Section A, as it pertains to capacitors rated under 600 VAC nominal. 1 E. NEMA CP-1, “Shunt CapacitorsI. 2. APPLICATION: 2.1 2.2 2.3 2.4 2.4.1 The correction specified in T

4、able 1 applies only to totally enclosed, U frame, NEMA design B (normal slip) and NEMA design D (5 - 8 percent slip) motors used on 480 V, three phase, 60 Hertz applications. NEMA design D motors below 75 HP should be corrected the same as design B motors. For more detailed motor specifications see

5、Standards EM1 and EMlX. For other types of motors consult the motor manufacturer for power factor correction requirements. Power factor correction capacitors shall be included as described in this Standard when specified on the Electrical Equipment Data Form (Form 2630). The word “shall“ as used in

6、this Standard is understood as a requirement; the word “should“ as a preference. DEFINITIONS: For purposes of this Standard the following definitions shall apply: Capacitor Cell - A capacitor cell is a single three phase capacitor. FORD MANUFACTURING STANDARDS = EFX POWER FACTOR CORRECTION EFX JUNE

7、1994 Page 2 = 2.4.2 Capacitor Assembly - A capacitor assembly is a single cell or two capacitor cells connected in parallel to make up the total required KVAR and housed in a NEMA I2 enclosure. 2.4.3 Multiple Capacitor Assembly - Two or more capacitor assemblies housed in a common NEMA 12 enclosure

8、and wired independently for two or more separate motor circuits. 3. CAPACITOR REQUIREMENTS: 3.1 Capacitor cells shall be Industrial Grade, rated 480 RMS VAC, three phase, 60 hertz. Three discharge resistors of not more than .47 megohms each and rated not less than one watt, shall be connected to the

9、 capacitor terminals in a closed delta configuration. The resistors shall discharge the capacitor to 50 volts or less within one minute after the capacitor source of supply is disconnected. Capacitor losses shall not exceed 0.5 watts per RvAR. 3.1.1 Capacitor cells utilizing pressure interrupter met

10、al casing, shall disconnect all three phases of power. 3.2 In order to minimize power losses, dielectric materials should include polypropylene or similar film materials. 3.2.1 Capacitor cells shall contain no polychlorinated biphenyls (PCB). 3.3 3.4 Capacitor cells shall be equipped with threaded s

11、tuds and nuts for termination of conductors with ring type connectors. Soldered connections and quick disconnect tab lug terminals are not acceptable. Each capacitor assembly shall have a nameplate which includes all data as specified in NEC, paragraph 460.12. Separate llCAUTION“ tags shall be affix

12、ed to each capacitor listing the name of the liquid dielectric material and the recommended disposal method, and a lCautionlt . Before Opening, Disconnect Main Power . Wait One Minute For Capacitor Discharge. The nameplate and CAUTION tags shall be readable on exterior of capacitor enclosure. FORD M

13、ANUFACTURING STANDARDS = EFX POWER FACTOR CORRECTION EFX JUNE 1994 Page 3 = 4. SELECTION AND APPLICATION: 4.1 GENERAL: 4.1.1 Power factor correction shall not be applied to production machines and equipment where: a) The total motor load is less than 7.5 HP. b) The application uses a single motor fo

14、r: reversing, plugging, jogging, inching, or two-speed operation. c) A clutch, brake, solid state rectifier, or DC voltage is connected to the load side of a motor starter in a single motor application. This exception does not apply when the motor is one of a group of motors being corrected as descr

15、ibed in 4.3.2. d) Motors. regardless of HP rating, are used only for adjustment purposes on an intermittent basis. An example of such limited duty is the slide adjustment motors on a press. e) Motor(s) that are controlled by solid state drives, unless authorized by requesting activity. 4.1.2 Conduct

16、or sizes for capacitor wiring shall be selected from Table 2. 4.2 SINGLE MOTOR APPLICATIONS: 4.2.1 On single motor applications rated 7.5 HP or more, the KVAR correction for NEMA Design B or D motors shall be selected from Table 1. The capacitor(s) shall be connected to the load side of the motor st

17、arter, between the contactor and the overload relay assembly as illustrated in Figure 1. The capacitor connections to the starter shall not restrict ready access to the overload heater elements or reset button. 4.2.2 Wiring between a single starter and the related capacitor(s) shall be identified wi

18、th wrap type adhesive bands marked lC1, lC2, lC3. The numbers shall correspond to the motor terminals to which the capacitor is connected (e.g., 1Cl to lT1, lC2 to lT2, lC3 to lT3). Refer to Figure 1 for an example of proper lead identification. FORD MANUFACTURING STANDARDS -_-_- -_- EFX POWER FACTO

19、R CORRECTION EFX JUNE 1994 Page 4 -_-_- -_- 4.3 MULTIPLE MOTOR APPLICATIONS: 4.3.1 Where a multiple motor application includes a single motor, 60 HP or larger, and one or more other motors with a total of less then 7.5 HP, the installation shall be treated as a single motor application as described

20、in 4.2.1. Example: A punch press with a 150 HP drive motor NEMA Design D, a 3 HP oil pump, and a l/2 HP lubrication pump. The small motors total less then 7.5 HP and are therefore not included. Since the press motor is a NEMA design D. 150 HP, a 45 KVAR capacitor assembly is selected from Table 1. T

21、he capacitor is connected to the starter as shown in Single Motor Applications Figure 1. 4.3.2 4.3.3 In multiple motor applications, KVAR correction shall be determined as follows: a) Each motor 60 HP or larger shall be considered as a single motor application described in 4.2.1. b) The horsepower o

22、f all remaining motors less than 60 HP shall be totalled. The KVAR correction shall be derived from the formula: KVAR = (total horsepower)/3 The capacitor value used shall be selected from Table 1. In all cases the exact or closest lower KVAR value shall be used. See Figure 2 for a typical applicati

23、on on a multi-motor machine. The capacitor cell or assembly required shall be controlled by a contactor selected from Table 3. a) The contactor coil shall be interlocked to allow the coil to be energized only when: 1. The control circuit is set for “Automatic“, and 2. After the motor starter coils a

24、re energized. b) On applications employing timed starting sequences (see Standard EXl, paragraph 6.4) individual contactors for controlling KVAR correction shall be energized after each related group of motor starter coils are energized. FORD MANUFACTURING STANDARDS = EFX POWER FACTOR CORRECTION EFX

25、 JUNE 1994 Page 5 = 4.3.4 5. 5.1 INSTALLATION: Capacitors shall be mounted only in the vertical position with the terminals up. 5.2 Capacitor assemblies shall conform to the following: 5.3 5.4 cl With any of the above methods of control, the capacitors shall remain continuously energized. In no case

26、 shall the capacitors be switched ON and OFF with each machine cycle. d) With any of the above methods of control, the capacitors shall remain continuously energized. In no case shall the capacitors be switched ON and OFF with each machine cycle. Where a multiple capacitor assembly is required, wiri

27、ng between contactors and capacitors shall be sequentially identified with wrap type adhesive bands marked lC1, lC2, lC3; The second capacitor 2C1, 2C2, 2C3, etc. The first number lists the unit or capacitor assembly number, the C indicates capacitor wiring, and the last digit the conductor number.

28、The identification shall be shown on related diagrams, in Figure 2. A typical example is shown a) All capacitor cells shall be mounted in type NEMA 12 enclosures. b) Terminal blocks for incoming conductors shall conform to Ford Manufacturing Standard ETl. cl Capacitor cells shall be spaced at least

29、9.53mm (3/8 in) apart to allow for access to mounting hardware and for air circulation. Capacitors shall be mounted on top of the control enclosure, but shall not be located directly above heat dissipating components. Wiring entering the capacitor enclosures shall be through the side, a minimum of t

30、hree (3) inches from the bottom. Enclosure covers and screws shall be readily accessible. Fuse status lights and monitoring indicator lights shall be readily visible. Wiring between the electrical control enclosure and the capacitor assembly shall conform to section 12 and 13 of Ford Standard EXl. C

31、onductors shall be selected from Table 2, and consist of type MTW or THHN not less than 19 strands. Conductors shall be connected to capacitors with ring type terminals (lugs) and to screw type pressure terminals on starters and contactors. m =lll07LbCl lln5345ll 4T=l m FORD MANUFACTURING STANDARDS

32、= EFX POWER FACTOR CORRECTION EFX JUNE 1994 Page 6 = 5.5 Fuses for a capacitor assembly shall be mounted in the capacitor assembly enclosure. These fuses shall be type KTK or equivalent and be rated 600 Volts; see section 6.4. 5.6 The dual-element fuse block and contactor specified in 6.3.1 shall be

33、 mounted adjacent to related motor starters in the electrical control enclosure. 6. OVERCURRENT PROTECTION: 6.1 Capacitors and the related circuitry shall be protected against overcurrent (short circuit) faults. Fuses as described herein are preferred for this purpose. 6.1.1 Capacitors shall have fu

34、se protection in each of the three phases per NEC. 6.2 PROTECTION FOR SINGLE MOTOR APPLICATIONS: 6.2.1 Single motor applications described in 4.1.2 do not require separate overcurrent protection for the capacitor wiring if the related motor, its controller, and wiring are protected as described in S

35、tandard EXl, part 4. However, protection for the capacitor(s) shall be provided within the capacitor enclosure as described in 5.8. The fuse ratings listed in Table 1 shall not be exceeded for capacitor cells. One or more unit capacitors may be protected by a single set of fuses where the maximum ra

36、tings listed are not exceeded. 6.3 PROTECTION FOR MULTIPLE MOTOR APPLICATIONS: 6.3.1 Where the contactor described in 4.3.3 is used to control the capacitors, a three pole, 600 V fuse block for dual element fuses shall be installed between the power source and the contactor. The fuse ampere rating s

37、hall be determined by the formula: 1.2 (amperes) X KVAR X 1.65 = amperes rating (select nearest practical rating of dual.element fuel. Example: To protect a 42.5 KVAR capacitor assembly proceed as follows: (1.2 X 42.5) I X 1.65 = 84 amperes. Note: In addition to the protection described above, the 4

38、2.5 KVAR assembly shall include protection for individual capacitor cells not exceeding the rating listed in Table 1. FORD MANUFACTURING STANDARDS =-= EFX POWER FACTOR CORRECTION EFX JUNE 1994 Page 7 =P=-= 6.4 BLOWN FUSE INDICATORS: 6.4.1 Each fuse within the capacitor enclosure shall be equipped wi

39、th an indicating lamp (mounted on exterior of capacitor enclosure) which glows when the fuse fails. A neon lamp with suitable resistor for use on 480 volts is acceptable. The lamps shall be dead front design and rated for the intended service. EXCEPTION:For metalized film type capacitor, an indicato

40、r lamp shall be provided to indicate the loss of more than 38 percent of the capacitors KVAR rating. At least two phases must be monitored. Blown fuse indicators are not required for this application. 6.4.2 It is recommended that during initial equipment start up, when motors are checked for rotatio

41、n, tools are being set up, etc., that the fuses be removed to isolate and protect the capacitors. Either the main fuses in series with the contactor on the control panel, or the individual capacitor fuses may be removed for this purpose. Table 1 - HP vs. KVAR Correction and Fuse Protection SINGLE NE

42、MA MOTORS MOTOR Design B Design D FUSE (maximum HORSEPOWER+ KVAR KVAR rating - amperes) 7-l/2 3 3 20* Unit 10 3 3 20* Capacitors 15 5 20* 20 6 z 20* 25 7.5 7.5 20* 30 9 9 30* 40 10 10 30* 50 13.5 13.5 30* 60 15 15 30* 75 18 22.5 * Capacitor 100 22.5 30 * Assemblies 125 30 37.5 * * Current limiting,

43、600 V, Type KTK or equal. * Dual-element, 600 V, Type FRS or equal. See Paragraph 6.3.1. + For group motor correction see paragraph 4.3.2. 150 35 * 200 42.5 El * 250 52.5 70 * 300 60 75 * FORD MANUFACTURING STANDARDS -_- -_-_- EFX POWER FACTOR CORRECTION EFX JUNE 1994 Page 8 -_-_- _-_-_-_- Table 2 -

44、 Conductor Size vs. Capacitor KVAR. Conductor Size - AWG No. 14 12 10 8 6 4 Maximum Capacitor KVAR 10 13.5 20 35 50 65 Table 3 - Contactor Size vs. KvAR. Contactor-NEMO Size No. 1 2 Maximum Controlled KVAR 13.5 26 5: NOTE: Denotes areas of change in previous issue. FORD MANUFACTURING STANDARDS EFX JUNE 1994 POWER FACTOR CORRECTION EFX Page 9 Flgure l-SINGLE MOTOR APPLICATION 480 VAC? 1 I 6Y -l& fff FUSED SWITCH OR I I I CIRCUIT BREAKER Fl F2 Jr1 -s v- 1Tl F2 0 7.5 HP OR LARGER Figure E-MULTIPLE MOTOR APPLICATION CIRCUIT BREAKER OR FUSED DISCONNECT AS SPECIFIED 3 w 5 HP F1