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Electric Capacitor Marking Guide
How to Decode Motor Capacitor Markings
- POST a QUESTION or COMMENT about decoding the letters and numbers found on motor start and run capacitors.
Electric motor start-run capacitor decoding guide.
This article explains the letters and numbers found on electric motor capacitors. The capacitor code is used to select the right device for your electric motor.
This electric motor capacitor article series explains the selection, installation, testing, & use of electric motor starter start and run capacitors used on various electric motors found in or at buildings such as air conditioner compressors, fan motors, some well pumps and some heating equipment. We also explain motor capacitor selection, troubleshooting, and replacement.
InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.
Complete Guide to Electric Motor Capacitor Markings
If you need to de-code markings on a capacitor, this table summarizes the various codes and marks used.
Many of these have been standardized by the EIA, the Electronic Industry Alliance, but you may find variations in abbreviations, in use of capital or small letters, and other codes.
Watch out: do not attempt electrical repairs if you are not trained and equipped to do so. Making a mistake can cause a fire or serious injury or death.
Electrical Capacitor Markings, Codes, Letters |
||
| Meaning | Capacitor Code | Examples |
| Capacitance microfarads |
µF uF mF MF |
25µF |
| Capacitance picofarads pF |
RRP RR=rating P=power 10p |
204 = |
| Capacitor Material Code (EU) | FKC | Metal foil and Polycarbonate dielectric film |
| FKP | Metal foil and Polypropylene dielectric film | |
| MKC | Metallized Polycarbonate foil | |
| MKI / PPS | Metallized Polypropylene foil | |
| MKS / PS | Metal foil and Polystyrene dielectric film | |
| MKT / PET | Metallized polyester foil. Mylar, Polyester or Polyethylene terephthalate PET capacitors. |
|
| Date of Manufacture | YYYY or |
2002 or |
| Frequency | Hz | 50/60 Hz |
| Mfg's Part Numbers Product Codes 2 |
Alpha-Numeric Strings |
SFT24T100H391B-F 3 |
| Operating Temperature Max | F or C | + 70C |
| Operating Temperature Min | F or C | - 40C |
| Polarization | Stripe or other |
Black + = Positive |
| Temperature Coefficients | ||
| Tolerance | +/- % | +/- 10% +5% |
| Tolerance Codes |
B | ± 0.1% |
| C | ± 0.25% | |
| D | ± 0.5% | |
| F | ± 1% | |
| G | ± 2% | |
| J | ± 5% | |
| K | ± 10% | |
| M | ± 20% | |
| Z | +80% -20% | |
AC Voltage Maximum |
V VAC WV |
370VAC |
EIA AC Voltage Table |
See EIA AC VOLTAGE TABLE |
|
AC Voltage |
1A | 10V |
| 1C | 16V | |
| 1E | 25V | |
| 1H | 50V | |
| 2A | 100V | |
| 2D | 200V | |
| 2E | 250V | |
DC Voltage |
VDC VDCW |
24VDC |
EIA DC Voltage Codes |
See EIA DC VOLTAGE CODES | |
| Wire Connections | S = start wire connector |
S, R, C |
Notes to the table above
- Capacitance rating or ability to store an electrical charge, given in
Microfarads = 10-6 Farads or 10-6F written as µF or uF or as MF, or occasionally as mF
Watch out: mF usually is used to indicate millifarads = 10-3 Farads
Nanofarads = 10-9 Farads or 10-6F written as nF
Picofarads = 10-12 Farads or 10-12F written as pf or mmF or uuF
Older small disc or ceramic capacitors use color bands to indicate capacitance and possibly tolerance. - Part numbers may indicate the capacitor's shape, type, and other features. Examples of capacitor types include ceramic capacitors, electrolytic capacitors, film capacitors, motor capacitors, safety capacitors, supercapacitors, ultracapacitors, tantalum capacitors.
Within the capacitor types are sub-types such as AC & Pulse film capacitors, aluminum organic polymer capacitors, arc protection devices, ceramic disc capacitors, and in addition, a host of termination or connector styles such as radial, screw, snap-in, soldering star, threaded stud, wire, wire-lead.
To translate these part numbers and product codes you will need to refer to the specific manufacturer's catalog.
Examples of the encoded capacitor features include: termination style (connector), case style, capacitance, voltage rating DC, voltage rating AC. - SFT24T100H391B-F - Example of a capacitor manufacturer's code as listed by mouser.com may encode and include the following information
Manufacturer: Cornell Dubilier
Product category: Motor start capacitor / motor run capacitors
Product: motor run capacitors
Termination style: Quick Connect
Capacitance: 390 pF
Voltage Rating DC: 100VDC
Minimum Operating Temperature: -40C
Maximum Operating Temperature: + 70C
Length/Height: 99.314mm
Depth/Thickness: 66.548mm
Life: 60,000 hours
Series: SF
Tolerance: 6%
Brand: Cornell Dubliner - CDE
Capacitance - nF: 039 nF
Diaelectric: Polypropylene (PP)
Product Type: Motor Capacitors
Factory Pack Quantity: 25
Source: Mouser Electronics, 1000 North Main St., Mansfield TX 76063 USA, Tel: 800-346-6873, email: sales@mouser.com - Voltage rating abbreviations on capacitors given as maximum or breakdown voltage that the capacitor can handle, may be given as "working voltage".
1 kV = 1000 Volts
EIA AC Voltage Code Table |
|
| Code | VAC |
| 2Q | 125 |
| 2T | 250 |
| 2S | 275 |
| 2X | 280 |
| 2F | 300 |
| I0 | 305 |
| L0 | 350 |
| 2Y | 400 |
| P0 | 440 |
| Q0 | 450 |
| V0 | 630 |
EIA DC Voltage Code Table |
||
| Code = VDC | Code = VDC | Code = VDC |
| 0E = 2.5 VDC | 2A = 100 VDC | 3A = 1 kVDC |
| 0G = 4.0 VDC | 2Q = 110 VDC | 3L = 1.2 kVDC |
| 0L = 5.5 VDC | 2B = 125 VDC | 3B = 1.25 kVDC |
| 0J = 6.3 VDC | 2C = 160 VDC | 3N = 1.5 kVDC |
| 1A = 10 VDC | 2Z = 180 VDC | 3C = 1.6 kVDC |
| 1C = 16 VDC | 2D = 200 VDC | 3D = 2 kVDC |
| 1D = 20 VDC | 2P = 220 VDC | 3E = 2.5 kVDC |
| 1E = 25 VDC | 2E = 250 VDC | 3F = 3 kVDC |
| 1V = 35 VDC | 2F = 315 VDC | 3G = 4 kVDC |
| 1G = 40 VDC | 2V = 350 VDC | 3H = 5 kVDC |
| 1H = 50 VDC | 2G = 400 VDC | 3I = 6 kVDC |
| 1J = 63 VDC | 2W = 450 VDC | 3J = 6.3 kVDC |
| 1M = 70 VDC | 2J = 630 VDC | 3U = 7.5 kVDC |
| 1U = 75 VDC | 2I = 650 VDC | 3K = 8 kVDC |
| 1K = 80 VDC | 2K = 800 VDC | 4A = 10 kVDC |
Example of How to Translate the Markings on a Motor Capacitor
Replacement capacitor for-sale listings may be described leaving you to interpret the numbers, such as this example capacitor marking:
35+5 uF +5%, 370VAC, 50/60Hz
Translation:
- Capacitance tolerance: rated tolerance.
This is a 35µF Start Capacitor (35 micro-farads) with an actual capacitance output as follows:
because there was a +5% but no - sign (such as +/- 5%) the manufacturer is saying the capacitor won't give less output (ultimately expressed in volts) than would be obtained from a devices that provides exactly 35µF of capacitance,
but it might provide as much as 5% more - or as much as 35 + (0.05 x 35) = an actual maximum capacitance of 36.75µF.
- Rated voltage Vn: 370 VAC - technically, the rms value of the sinusoidal AC voltage that can be applied to the capacitor in normal working conditions.
In plain English, this capacitor can be used at voltages up to 370 Volts Alternating Current.
Use of this capacitor at lower voltages than 370 VAC is acceptable (so you can use it on a motor powered at 120 VAC Volts-Alternating Current or at 240 VAC). - Duty Frequency Range: 50/60 Hz. The capacitor can be used at a frequency range of 50-60 HZ. Use at higher frequencies is possible provided the voltage, current, temperature, and power limits are complied-with.
In plain English, this capacitor can be used on either 50 cycle or 60 cycle current systems
Other capacitor ratings that you might see marked on a capacitor's case
- Part number: often made up of a capacitor series followed by the capacitance and the device physical dimensions and followed further by codes indicating special accessories
- Operating Temperature class, such as a minimum and maximum operating temperature as measured at the surface of the capacitor
- Storage temperature
- Loss angle tanδ, for example The value of the tangent of the loss factor measured at 50 Hz, 20°C at the rated voltage is: tanδ ≤ 20·10– 4
- Maximum permissible overloads: the capacitor can operate under the given overload conditions throughout its temperature class range, e.g. given as Vmax = 1.1 Vnominal
- Pulsed stress: the capacitor is capable of tolerating steep wavefronts with maximum voltage variation speed of a specified voltage V/us or volts per microsecond
- Insulation resistance measured between the capacitor's terminals and its case
- DC operation: indicating capacitors that can be operated with DC or Direct Current voltage, typically Vdc ≤ √ 2 Vn
Note that we do not ask InspectApedia readers to understand the calculation that actually tells us what a given capacitor's output (in Volts) will be over time for a given input current in amps. Readers who want to know more about how a capacitor actually works will want to search and read about the Capacitor i-v equation for which a nice explanation is at "Capacitor i-v equation in action" by spinningnumbers.org found at https://spinningnumbers.org/a/capacitor-iv-equation-in-action.html
Electric Motor Capacitor Working Class
Capacitors are also rated in working classes which describe the expected service life of the capacitor in hours, assuming the cap has been properly selected.
Electric Motor Capacitor Working Class |
|
| Working Class | Rated life in hours of use |
| Class A | 30,000 |
| Class B | 10,000 |
| Class C | 3,000 |
| Class D | 1,000 |
Notes to the table above
Sources:
Kemet, Capacitors for AC Motor Applications, [PDF] Kemet Electronic Components, 941 Linda Vista Dr, West Chester, PA 19380 USA, Website: http://www.kemet.com/ retrieved 2018/06/18, original source: http://www.kemet.com/Lists/ProductCatalog/Attachments/158/F9000_GenInfo_MotorCaps.pdf
WEG, Specifications of Electric Motors [PDF], retrieved 2018/06/18, original source: http://ecatalog.weg.net/files/wegnet/WEG-specification-of-electric-motors-50039409-manual-english.pdf
...
Continue reading at CAPACITOR SIZE DETERMINATION for ELECTRIC MOTORS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.
Or see these
Recommended Articles
- BASIC ELECTRICAL TESTS for BURNED OUT COMPRESSOR MOTORS
- CAPACITOR TYPES, for MOTORS
- CAPACITORS for HARD STARTING MOTORS
- CAUSES of HARD STARTING ELECTRIC MOTORS
- CAPACITOR SIZE DETERMINATION for ELECTRIC MOTORS
- COPELAND ELECTRICAL HANDBOOK [PDF]
- HARD STARTING COMPRESSOR MOTORS
- HOW a STARTING CAPACITOR WORKS
- HOW to TEST the MOTOR to ID TERMINALS
- LOCATE the STARTING CAPACITOR
- MOTOR CAPACITOR WIRING GUIDE
- STARTING CAPACITOR SAFETY
- TEST a MOTOR START or RUN CAPACITOR
- HARD STARTING ELECTRIC MOTOR CAUSES
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CAPACITOR CODE & MARKING DECODING GUIDE at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.
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Citations & References
In addition to any citations in the article above, a full list is available on request.
- Supco, Sealed Unit Parts Company, PO Box 21, 2230 Landmark Place, Allenwood, New Jersey, 08720, Tel: 732-223-6644, 201-449-3300, email: info@supco.com, provided the compressor starting capacitor and packaging information (purchased by the author from an air conditioning parts supplier in New York) - our example uses a Sealed Unit Parts Company Solid State part No. RSC 10 115V starting capacitor which was designed for installation on refrigerators and freezers. See www.supco.com/
- [1] "The E Class Advantage", Supco (op cit), describes the company's advanced start/run capacitor products. Web search 08/04/2011, original source: http://www.supco.com/eclassadvantage.htm Quoting from that article:
The SUPCO E-Class Series comprise the most advanced developments in start device technology:
1. Voltage sensing technology that monitors for motor start (current sensing devices require internal fuse protection).
2. A 2-wire connection that simplifies installation
3. A secondary timing circuit that ensures that the capacitor is not permanently left in the start winding circuit
4. A fully electronic device - minimizing the limitations of mechanical devices and secondary fusing associated with triac devices
5. A start device matched with an appropriately sized capacitor to cover the range of compressors for the intended application (one size does not fit all)The use of compressor start devices results from a need to ensure that a compressor (usually air conditioning) will start under voltage conditions that are less than ideal. As discussed, several options exist in the market to address compressor start concerns. Start devices exist in many forms for specific applications. SUPCO provides a full range of products in all relevant technologies to effectively match the proper start device to the application. Care should be taken to utilize a device that meets the requirements of the job. Extra caution should be observed when employing the "one-size-fits-all" and "a bigger capacitor is better" approach to applying a start device. Consult SUPCO, a manufacturer with a complete product range, to ensure the greatest success in the start device application.
- [2] "Motor Start and Run Capacitors", AFCAP (African Capacitors Limited), web search 08/05/2011, original source: http://www.afcap.co.za/manual/Part2.pdf
- COPELAND ELECTRICAL HANDBOOK [PDF] free download from Emerson Climate Controls, at InspectApedia.com
- [3] "Kenmore model 580. 75121 room unit air conditioner wiring diagram", Sears Roebuck window air conditioner wiring diagram for a typical room or window air conditioner
- George Fazio, reader, contributed comments on failed starter capacitor diagnosis by noting the bulged capacitor ends. 09/25/2009
- Troubleshooting Compressor Problems," Henry Puzio, Fuel Oil & Oil Heat with Air Conditioning Magazine, June 1993, p. 39
Tom Morris, Engineer, capacitor discussion and correction to the original data. Email to D Friedman 5/29/2006 - Thanks Tom for critical editing. The text above explaining about capacitors was suggested by Mr. Morris. The original text of the 1993 compressor diagnosis article had the resistance explanation backwards. - Thanks to reader Diane McGivney for asking about air conditioner compressor motor starting capacitor costs and typical air conditioner service call fees - (May 2010)
- Thanks to reader James Oiler for reporting on the replacement of a heat pump starter capacitor, August 2010.
- In addition to citations & references found in this article, see the research citations given at the end of the related articles found at our suggested
CONTINUE READING or RECOMMENDED ARTICLES.
- Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: info@carsondunlop.com. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The HOME REFERENCE BOOK - the Encyclopedia of Homes and to use illustrations from The ILLUSTRATED HOME .
Carson Dunlop Associates provides extensive home inspection education and report writing material. In gratitude we provide links to tsome Carson Dunlop Associates products and services.
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