blower fan issues
Since the new capacitor is from an electronics supplier, I suspect it is for DC only. A motor capacitor must be AC.
There are basically 4 types of electrolytic capacitors.
1) DC, also known as filter capacitors. These are for use on DC circuits only, they will store a charge in only one polarity, not both as in AC. They are typically used to 'smooth out' a pulsating DC circuit, though they may also be used as energy storage. They range from less that 1 ufd to many thousand ufd, and voltages from less that 10 to more than 1000.
2) Motor start capacitors. These are for AC power, though they'll work on DC as well. These are what's under the 'hump' on a capacitor-start single phase motor. They range from about 100 ufd to about 500 ufd. They are designed to be operated for a limited time, usually only a few seconds. they voltage range is usually 110 to 550.
3) Motor run. These are also for AC power, and will work on DC. These are designed to be operated continuously. This is the type you have. They are usually about 10 ufd to 200 ufd. Voltage is usually 110 to 550.
4) Power factor correction capacitors. These are for AC power, and will work on DC. They're usually found in huge industrial buildings, and power plants. They are usually rated in kVars (kilo voltamps reactive), not ufd. They are installed directly across an AC power line, for the purpose of improving power factor. Voltage ranges from 240 to thousands of volts. (I know, this isn't DIY, but they certainly exist, and I've installed plenty of them).
All capacitors are rated in capacitance and voltage. Capacitance is usually expressed as ufd (micro farad). This relates to their ability to stare an electrical charge. A 100 ufd capacitor is smaller than a 500 ufd one, alot like a 1 gallon bucket is smaller than a 5 gallon one. If you're replacing one, the ufd rating must match.
Voltage is simply the maximum amount of electrical 'pressure' it can safely withstand. A replacement capacitor can have a higher voltage rating, but not lower. The voltage rating has no effect whatsoever on capacitance. Be careful when using a higher voltage capacitor, the higher the voltage, the larger the case size.
A word of caution here; when working with capacitors, remember that they can store a charge for a long time (years). This charge can knock you right across the room! Once power has been de-energized, short the terminals out with a screwdriver. If you see a nice arc, and hear a nice SNAP, you'll be glad you did!
Motor run capacitors can be found at motor repair shops, HVAC shops, and industrial supply houses (Grainger and the like).
With the proper capacitor, I'll bet your motor will run fine.
P.S. Grainger has a 25 ufd motor run capacitor #2GU15. It is rated at 440 volts, there's really no difference between 440 and 450.
Last edited by micromind; 09-11-2008 at 09:38 PM.
Reason: Added P.S.