anyone know capacitors?

[0rion]

My neighbor had the capacitor on his electric log splittle pop and he can't find the exact capacitor. It's a 60uF 300v capacitor. Can he use a 60uF 450v capacitor? I forget if the voltage is the working voltage or just the limit of the capacitor. In other words does it ramp it up and hit the motor with 450v or does that mean it will only store 450v?

[NE-Firebird]

As long as it's the same type of capacitor, then you're fine.
The voltage listing on a capacitor is the maximum voltage. For various reasons, you always want a factor of 2x->3x++.

For an electric motor capacitor:

From: http://en.wikipedia.org/wiki/Motor_capacitor
Run capacitors
Run capacitors are mostly polypropylene film capacitors and are designed for continuous duty, and they are energized the entire time the motor is running.[1] Run capacitors are rated in a range of 1.5–100 microfarads (µF or mfd), with voltage classifications of 370 V or 440 V.[1] Single phase electric motors need a capacitor to energize a second-phase winding. If the wrong run capacitor is installed, the motor will not have an even magnetic field, and this will cause the rotor to hesitate at those spots that are uneven. This hesitation can cause the motor to become noisy, increase energy consumption, cause performance to drop, and cause the motor to overheat.

Start capacitors
Start capacitors above 20 microfarads (µF) are always non-polarized Aluminum Electrolyic Capacitors [3] with non solid electrolyte and therefore they are only applicable for the short motor starting time.

Start capacitors briefly increase motor starting torque and allow a motor to be cycled on and off rapidly.[1] Start capacitors have ratings above 70 microfarads (µF), with four major voltage classifications: 125 V, 165V, 250 V, and 330 V.[1] A start capacitor stays in the circuit long enough to rapidly bring the motor to 3/4 of full speed and is then taken out of the circuit, such as by a centrifugal switch that releases at that speed. The motor after that runs more efficiently with a run capacitor.

Examples of motor capacitors are: a 35 µF/mfd, at 370 V, run capacitor, or an 88–108 µF/mfd at 250 V start capacitor.[1]


BTW, for electronic circuit boards, the value, the type, the internal resistance, the impedance, the accuracy rating, etc may be very important - especially for any high-speed chip/circuit/termination/etc.

Good Luck!

[0rion]

it looks like he'll be fine using a 60uF at 450v capacitor then....thanks for the info.