Capacitors (running or starting)

Thread Starter

peterangelo

Joined Feb 12, 2012
2
hello,

i have problem with my exhaust blower installed at our mini theatre. the blower rating is 450 watts, single phase (220-240 Vac), 50/60 hz. the blower was functioning normally but when fluctuation occurred the blower suddenly become weak. it can't extract heat already but it is running. i tried to checked the input voltage but it alright. i checked the capacitor, which i don't know if it is running or starting cap, but found out that it is far from its value. the cap value is 40microfarad but the reading was only 19 nanofarad. does this mean my cap is already defective or maybe there's something wrong with the motor windings?
 

Thread Starter

peterangelo

Joined Feb 12, 2012
2
yes. i removed the cap before measuring it. there's only one cap in there but i'm wondering if it is a running cap or starting cap.
 

PackratKing

Joined Jul 13, 2008
847
I will concur w/ Shortbus........it is a run cap.

Be sure to perform any more testing on the ductwork the unit is normally mounted on, as the amp draw of the motor will be excessive if operated in free air w/o its baffles.

Excessive to the point the motor will cut out on its internal thermal overload, and will very soon begin to lose the magic smoke it works on :D if it hasn't already.
 

R!f@@

Joined Apr 2, 2009
9,682
Funny... If it was one cap, It was always starting.

Atleast that's all I have seen here so far.

If there were a running one, it would have two of them.

Guess I was wrong. Or am I?

{ED}

Hey I was right somewhat..They are dual caps.

So it was the running one that faulted.
 

shortbus

Joined Sep 30, 2009
7,078
Funny... If it was one cap, It was always starting.

Atleast that's all I have seen here so far.

If there were a running one, it would have two of them.

Guess I was wrong. Or am I?

{ED}

Hey I was right somewhat..They are dual caps.

So it was the running one that faulted.
Check out our Ebook - http://www.allaboutcircuits.com/vol_2/chpt_13/9.html ,look for "split-capacitor" motor. This motor type has no start capacitor, just a run cap. This is often used for fans and blowers.

What your referring to is a 'capacitor start - capacitor run' motor, not the same animal.:)
 
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