What Size Capacitor For 1/2 Hp Motor

Start Capacitor Selection Guide

A start capacitor is used to briefly shift phase on a start winding in a single stage electric motor to create an increase in torque. Start capacitors possess a very large capacitance value for their size and voltage rating. As a result, they are only intended for intermittent duty. Because of this, start capacitors volition neglect after existence left energized for too long due to a faulty starting excursion on a motor.

Index

Overview

Start vs. Run Capacitors

Kickoff capacitors requite a large capacitance value necessary for motor starting for a very brusque (seconds long) catamenia of time. They are only intermittent duty and will fail catastrophically if energized too long. Run capacitors are used for continuous voltage and electric current command to a motor's windings and are therefore continuous duty. They are generally of a much lower capacitance value.

Are start and run capacitors interchangeable?

Yes and no. In unusual circumstances, a run capacitor could be used as a start capacitor, merely the values available are much lower than the values ordinarily available for dedicated start capacitors. The capacitance and voltage ratings would have to match the original starting time capacitor specification. A startcapacitor can not ever be used as a run capacitor, because it could not handle current continuously (only a couple of seconds).

Watch the video tutorial below to larn the differences between offset and run capacitors.

What is a resistor and do I demand one?

Most replacement start capacitors will not include a resistor. You can check the condition of the quondam one by checking the resistance value, or just replace it with a new i. This should read somewhere around 10-20k Ohms and around two watts. The resistors are usually either soldered or crimped to the terminals. The purpose of the resistor is to bleed off residual voltage in the capacitor after it has been disconnected from the circuit later on motor start upward. Not all start capacitors volition utilise one, equally there are other means to achieve this. The of import part is if your original capacitor had one, you lot'll need to replace it on the new capacitor.

Learn how to install a drain down resistor on your offset cap.

Troubleshooting

How practice I know if my start capacitor is bad?

Most electric beginning motor capacitor failures are one of two types:

"The Starting time Cap blew its guts out!" This is what we call catastrophic failure. It is usually acquired past an electric motor's starting excursion being engaged besides long for the intermittent duty rating of a start cap. The top of the get-go cap has literally been blown off, and the insides have been partially or fully ejected.

Ruptured Pressure Relief Cicatrice Similarly simply non quite as dramatic, a start cap may just showroom a ruptured pressure relief cicatrice. In either instance, it's easy to tell that the start cap is in need of replacement.

My motor is slow to start. Is my start capacitor bad?

The answer to this question is maybe. Your start capacitor may have lost its capacitance rating due to wear and age, or yous may have other non-capacitor related issues that have to do with other motor components.

Watch the video below on how to supercede a start capacitor.

Specifications

Most starting time capacitor applications employ a rating of l-1200 uf capacitance and voltages of 110/125, 165, 220/250 and 330 VAC. They are besides usually always fifty and 60 Hz rated. Instance designs are typically round and cast in black phenolic or Bakelite materials. Terminations are unremarkably ¼" push on terminals with ii terminals per connection post.

Voltage

Select a capacitor with a voltage rating at or higher up the original capacitor. If you're using a 370 volt capacitor, a 370 or 440 volt one will piece of work. The 440 volt unit of measurement will actually terminal longer. A capacitor will have a marked voltage indicating the accpetable top voltage, not operational voltage.

Capacitance

Select a capacitor with a capacitance value (given in MFD, uf or microfarad) that is equal to the original capacitor. Practise not deviate from the original value, as it sets the operational characteristics of the motor.

Frequency (Hz)

Select a capacitor with the Hz rating of the original. Nearly all replacement capacitors will be labeled 50/60.

Connection terminal mode

Almost every capacitor volition use a ¼" flag way push button-on connector. The next question is, "How many terminals per final post are needed for the awarding motor?" Nearly start capacitors have two terminals per postal service, and well-nigh run capacitors will have either three or 4 terminals per post. Verify that your selected capacitor has at to the lowest degree the number of connection terminals per connection post as the original motor capacitor.

Case shape

Nearly all first capacitors have a round case. Round run capacitors are by far the nearly common, only many motors still use oval designs. Electrically speaking, there is no difference. Fit is the only question hither. If space in the mounting box is non limited, the example style does non matter.

Instance size

Just like case shape, overall size makes no difference electrically. Select a capacitor that will fit within the space provided.

Product Selection

110/125 VAC

Capacitance Value	Product ID
108-130	SC0005
161-193	SC0008
189-227	SC0011
200-240	SC0089
216-259	SC0014
233-280	SC0017
270-324	SC0020
324-389	SC0023
340-408	SC0026
378-454	SC0029
400-480	SC0032
460-552	SC0035
540-648	SC0038
590-708	SC0041
708-850	SC0044
829-995	SC0047
1000-1200	SC0050

220/250 VAC

Capacitance Value	Production ID
59-71	SC0053
64-77	SC0056
72-86	SC0059
88-106	SC0062
108-130	SC0065
124-149	SC0068
145-174	SC0071
161-193	SC0074
189-227	SC0077
216-259	SC0080
340-408	SC0083
430-516	SC0001
630-750	SC0086

165V

330V