Dazed and Confused - About Capacitators

[Susan_in_SF]

Hi Guys ,
I noticed that the motor for my new-old Inca 570 jointer/planer has a capacitor hanging next to the 220v motor. With all the AC motors in my garage, none of them, except for this one and for my little surface grinder, has capacitors. I tried reading up on it via google, but didn't find answers to my questions. So, I hope someone here can educate me.

Here are a few of my questions
Do all AC motors need capacitors?
Are copacitators ever built into the motor?
Is it a big no-no to run a motor without a capacitor?
Is there any important info about capacitors that I didn't ask?

Ok. As you can tell, my Friday nights are full of non-stop parties and excitement ;-) as I get my swerve on with capacitators.

 

[cdhknives]

All? No. Those that do, do require them.
Sometimes they are on a big blister housing on the side. They are usually too large to be truly built in. No capacitor usually means the motor has a starting winding and a running winding.
Yes. It won't start running and could burn up if left on long enough.
They die and require replacement. Size and capacity are important. Other methods of starting single phase motors include reduced voltage and starting coils. There is usually a switch (internal) that disconnects the capacitor (or starting coil) once the motor is nearly up to speed. Basically not having the capacitor in the circuit results in a motor with near zero starting torque.

 

[Groundhog]

Yeah, the parties are going on hot and heavy here in the Flat-lands too - as I read discusions about capacitors.

 

[FOMOGO]

Cocktails, and capacitors here in the Rockies also. Just doesn't get any better. Cheers, Mike

 

[Ulma Doctor]

Hi Susan,
usually single phase Alternating Current motors that require lots of starting torque use a capacitor to start the motor rapidly.
if the motor requires high starting torque AND may have high constant loads, a Run and a Start capacitor are used in the same motor.
the start capacitor starts the motor,then the Run capacitor(s) keeps the motor at optimum speed
I have not seen a capacitor built into a motor as an integral part, but i have seen replaceable capacitors inside of the motor frame enclosure on a few different motors.

if you find a capacitor anywhere in your motor or electrical system,
treat it like it is charged up and do not handle the capacitor unless it has been discharged.
i tell people to handle capacitors as if they were a rattlesnake

 

[markba633csi]

Did you know that there are no TRUE yams in America? They're all sweet potatoes. Or maybe you'd rather discuss capacitors?
Mark S.
(overheard at a recent party)

 

[tweinke]

My idea of a fun night involves working in my shop.................... But watch out for the capacitors because like Ulma Doctor said they can bite and it wont be the kind of swerve you want to get on.

 

[Mr Mike]

Hi Guys ,
I noticed that the motor for my new-old Inca 570 jointer/planer has a capacitor hanging next to the 220v motor. With all the AC motors in my garage, none of them, except for this one and for my little surface grinder, has capacitors. I tried reading up on it via google, but didn't find answers to my questions. So, I hope someone here can educate me.

Here are a few of my questions
Do all AC motors need capacitors?
Are copacitators ever built into the motor?
Is it a big no-no to run a motor without a capacitor?
Is there any important info about capacitors that I didn't ask?

Ok. As you can tell, my Friday nights are full of non-stop parties and excitement ;-) as I get my swerve on with capacitators.

Here are a few of my questions
Do all AC motors need capacitors? ----> No: If it needs hi torque it has a cap - like a grinder, to get the wheels going.

Are copacitators ever built into the motor? ----> Yes: they can be hidden - attached inside the motor housing

Is it a big no-no to run a motor without a capacitor? ----> Yes: windings can overheat & burn out due to excessive amp draw. you will usually hear a loud humming noise as well.

Is there any important info about capacitors that I didn't ask? ----> Many: Caps are like a battery in that even if you unplug the power they hold a charge that can shock you. caps are found in both 110V and 220V circuits. Caps are used on DC motors too. Don't short out a cap it can explode or catch fire - usually just sparks.

 

[Tozguy]

If you have a capacitor hanging beside the motor then chances are it has already been replaced a time or two. Capacitors are consumables and may need to be replaced to get the best performance from the motor.

It is not always possible to find the a size that fits in the original position on the motor. So sometimes they are just wired in and hung somehow beside the motor. Normally the capacitors are covered so you don't electrocute yourself.

My lathe motor has two capacitors, a start cap. and a run cap. The start cap has been changed twice when the lathe got to be slow starting. A lot of start and stop work on the lathe is hard on the start cap.

 

[CluelessNewB]

Not all motors have capacitors. Three phase motors don't have them. Smaller single phase motors like those used for fans don't have them. Many of the old Sears motors (Crafstman, Dunlap, Companion) have start capacitors inside the base. They are flat shaped capacitors rather than the typical round ones on other motors. Some motors have the capacitors remotely mounted rather than attached to the motor.

Here is a picture of a Sears motor that has the capacitor in the base: