Many engines such as washing machines, refrigerators are single phase motors. The problem of feeding a 230 V motor with a single phase is that it does not generate the torque required for starting. You should "trick" the engine and generate a fictitious phase using a capacitor sand in this way get the necessary torque. To get the best and most powerful torque phase, which will result in a washing machine or fridge working better and harder, centrifuging better, and with more power you must calculate the capacity of the capacitor to get this lag of 90 °. You should ignore these "urban legends" that you could read online which says that a bigger capacitor gets more power, that's completely false and it should develop a failure in your washing machine or fridge. In fact if the capacitor is too big may be the chance that the gap is 360 °, ie 0 ° so that the single-phase motor will not have any torque and power.
The higher starting torque for single-phase motor is obtained when the lag we get with our capacitor is 90 °. If we want to get this gap we must calculate the capacitor as follows.
We imagine that we have a 150 W motor and cos fi = 0.85 (a typical value)
Power = V x I x cosfi
I = 230 x 150 x 0.85
I = 0.767 Amperes
The apparent power (sum of active power, reactive power 150W +) = V x I = 176 VA
Calculation of inductive reactance (XL):
Apparent power = I ^ 2 x XL;
XL = apparent power / I ^ 2 = 176 / 0.76 ^ 2 = 305 Ohm
Calculating the capacity of the capacitor - single phase motor capacitor:
XL = 1 / (2 x pi x frequency x C)
C = 1 / (2 x pi x frequency x XL)
C = 1 / (2 x 3.14159 x 50 x 305) = 10.43 uF (micro Farad)
Therefore, the ideal capacitor single phase motor optimal for this example is 10.43 uF, and 10.43 micro Farad capacitor is not a value that we are able to find in the market, we muat choose the value that best approximates, in this case 10 micro farads.