Resistance is a constant pushback against electrical force, much like friction. Inductance is resistance to a change in electrical force, much like inertia. If current flows through a circuit with high inductance, the current will continue flow at a similar rate, resisting any changes to the flow.

As the frequency increase, the reactance decreases. As the frequency increases, the impedance increases. These are referred to as inductive reactance and capacitive reactance. Impedance is a crucial concept to understand as most electronic circuits utilize capacitors and inductors.

Resistance is simply defined as the opposition to the flow of electric current in the circuit. Impedance is opposition to the flow of AC current because of any three components that is resistive, inductive or capacitive. It is a combination of both resistance and reactance in a circuit.

Without the capacitor the motor will not start automatically but without a capacitor, a flick on the shaft will make the single phase motor run in either direction, provided that the main winding is operation as it should do.

Multiply 0.5 times the square of the voltage. Call this result “x.”. Continuing the example, you have 0.5 times 11.5 volts times 11.5 volts, or 66.1 square volts for “x”. Divide the start-up energy requirement, in joules, of the motor by “x” to arrive at the capacitor size needed in farads.

You mainly need to look at 2 values: the voltage and the capacity -both are written on most capacitors-. For example, if you are going to charge a capacitor with 24V, you need to make sure your capacitor will support that voltage; so you’ll need a capacitor for at least 25V (plus error margin).

Each color painted on the capacitors body represents a different number. The color codes used to represent the capacitance values and capacitance tolerance is similar to that used to represent resistance values and resistance tolerance. Generally, the capacitors are marked with four or more color bands.

The fifth band represents the working voltage of the capacitor (example 250V-red and 400V-yellow). The capacitor color code for ceramic capacitors is shown in the above figure in which first column represents different types of colors, the second column represents the value indicated by a specific color.

A capacitor that has a decimal is typically measured in uF. For example: .47 = .47 uF = 470 nF. The letter on a capacitor designates the tolerance. J = +/- 5% K = +/- 10%

Ceramic capacitors

Electrolytic capacitors

Motor start/run caps are non-polarized electrolytics And that’s the long and short of it- they’re ‘ac’ capacitors, actually they’re two polarized capacitors back-to-back, inside a common case. Polarized electrolytic capacitors are for DC-only applications like DC supply filtration.

At low frequencies, there is enough time for a considerable amount of charge to collect on the capacitor. This means there is a large “reverse voltage” on the capacitor so the sum of the capacitor’s voltage and the voltage of the ac source is nearly zero. That means the current will be nearly zero.