Running capacitors for domestic equipment
| Capacitor (MFD) | Equipment |
| 2.00 | Table fan |
| 2.25 | Table fan |
| 2.50 | Ceiling fan |
| 3.00 | Table fan |
| 3.15 | Exhaust fan |
| 3.50 | Exhaust fan |
| 4.00 | Exhaust fan |
| 6.00 | Grinder motor |
| 8.00 | Washing machine |
| 10.00 | Motor 0.375 kW (½ HP) |
| 12.50 | Motor 0.375 kW (½ HP) |
| 15.00 | Motor 0.375 kW (½ HP) |
| 18.00 | Motor 0.75 kW (1 HP) |
| 20.00 | Motor 0.75 kW (1 HP) |
| 25.00 | Motor 1.125 kW (1½ HP) |
| 30.00 | Motor 1.125 kW (1½ HP) |
| 36.00 | Motor 1.125 kW (1½ HP) and AC |
Starting capacitors for motors
| Capacitor | Equipment |
| 40/60 | Motor 0.18 kW (¼ HP) |
| 60/80 | Motor 0.25 kW (1/3 HP) |
| 80/100 | Motor 0.375 kW (½ HP) |
| 100/120 | Motor 0.55 kW (3/4 HP) |
| 120/150 | Motor 0.75 kW (1 HP) |
| 150/200 | Motor 1.125 kW (1½ HP) |
| 200/250 | Motor 1.5 kW (2 HP) |
The simplest way to explain the mechanics of a capacitor would be to compare it to a battery. Both store and release electricity. Capacitors are charged with electricity, then releases its stored energy at a rate of sixty times per second in a 60 cycle alternating current system. The sizing is critical to motor efficiency just as sizing of batteries is critical to a radio. A radio that requires a 9V battery will not work with a 1.5V size battery. Thus, as the battery becomes weaker the radio will not play properly. A motor that requires a 7.5 mfd capacitor will not work with a 4.0 mfd capacitor. Much the same way, a motor will not run properly with a weak capacitor. This is not to imply bigger is better, because a capacitor that is too large can cause energy consumption to rise. In both instances, be it too large or too small, the life of the motor will be shortened due to overheated motor windings. Motor manufacturers spend many hours testing motor and capacitor combinations to arrive at the most efficient combination. There is a maximum of +10% tolerance in microfarad rating on replacement capacitors, but exact run capacitors must be replaced. Voltage rating must always be the same or greater than original capacitor whether it is a start or run capacitor. Always consult manufacturers to verify correct capacitor size for the particular application.
ReplyDeleteDifferent brand of the capacitors sound differently in different applications. The V-caps I use as coupling caps between driver and power tubes in my amplifiers, but they may sound different as an output cap of a preamp. A different sort of coupling, yours might work depending on the input impedance of the amp your driving. Impedance determines coupling capacitor value, often manufactures choose an excessively large cap for a preamp output because they do not know the impedance of the power amplifier and it could be as low as 10K.
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