A buyer searching for Start Capacitor is usually trying to stop a bad substitute. A motor is specified by power, speed, voltage, duty, and the mechanical interface. The notes below are selection criteria for a Start Capacitor. They are not a catalog promise. Confirm every rating on the current datasheet, drawing, or test report for the revision you will receive.
What has to be true of Start Capacitor
A motor is specified by power, speed, voltage, duty, and the mechanical interface. For a Start Capacitor, start from the duty, then the interface to the rest of the machine or the room, then the document that proves the claim. A lower price that leaves one of those blank is a different product.
Start Capacitor is easy to confuse with Speed Controller. If the quote could be read as either, add the line that separates them: the rating, the fitment, or the standard named below. Link the drawing number to that line so receiving inspection can reject the wrong one.
Numbers that change the quote
| Line | What to write for Start Capacitor |
|---|---|
| Interface | Shaft size, and feedback if it is a servo. |
| Drive | Whether it will run on a VFD. Insulation and bearing measures may change. |
| Power and speed | Kilowatts or horsepower and rpm at the rated point. |
| Electrical | Voltage, phases, frequency, and current. |
| Duty | Continuous or intermittent, and the ambient. |
| Enclosure | The enclosure code and the mounting, such as foot or flange. |
How to compare two offers
Lay both quotes for Start Capacitor on one sheet and line up interface, drive, and power and speed. If a cell is empty, the offer is not finished. Ask for the missing line in writing. When those match, the honest difference is lead time, the test evidence, and who carries the warranty. Do not average a fully specified Start Capacitor with a cheaper line that omitted interface.
Documents worth having before the deposit
IEC 60034 is the usual rotating-machinery family. Ask which ratings on the nameplate follow it. The file should name Start Capacitor and the revision, not only the supplier’s homepage. A factory quality certificate such as ISO 9001 can sit beside that file. It does not replace it.
Failures that show up after delivery
- Mismatching the shaft.
- Forgetting the service factor or the duty.
- Putting a standard motor on a VFD without asking about insulation and bearings.
On a Start Capacitor, the expensive version of the first mistake is discovering it after the goods are in the crate. Put the rejection condition in the purchase order while the supplier can still restate the offer.
A worked RFQ line
Use this shape, then replace the brackets with your duty: “Start Capacitor — State power, speed, voltage, phases, duty, and frame or shaft.” That sentence is a template, not a rating of any brand. If a supplier’s datasheet uses different units, convert them onto this sheet so the next offer can be compared.
Where words like RoHS / CE belong
Searches often add a constraint to Start Capacitor: RoHS / CE, or explosion-proof / ATEX. Keep those on this page. RoHS is a material limit. CE is a declaration that lists the rules relied on. Ask for the document that names this part number and revision. ATEX or IECEx is a certificate for a zone, a gas or dust group, and a temperature class. An IP rating does not grant it. Skip the mark if the site is not hazardous. If you need a third constraint, add it as another line on the same drawing. A second URL that only swaps the adjective does not give a buyer a second fact.
Related in this section: how to specify Speed Controller.
Questions buyers actually ask
What should an RFQ for Start Capacitor include?
State power, speed, voltage, phases, duty, and frame or shaft.
Is a cheaper Start Capacitor the same part?
Only if interface, drive, and the documents match. A missing line is a different offer.
Do waterproof, OEM, or IP words need their own page?
No. For Start Capacitor they are extra lines on this specification. Ask for the test or the drawing that gives the word a value.