AC motor running too fast

Thread Starter

Patyome

Joined Jun 16, 2022
4
Hello friends!


First of all, let me say that I am not an engineer, however I found this forum and decided to try my luck with a problem I have with an electric motor.

The motor belongs to a small vacuum cleaner, specifically the Conga Duostick Easy.

The problem is that the AC motor started to make a number of rotations much faster than normal and, consequently, make a lot more noise.

I have already removed the vacuum motor and replaced the Polypropylene Film Capacitor - 0.1 UF - 15mm, but to no avail.

The brushes look fine. It seems that there is still a lot of carbon to be spent. They have a "half moon" tip form, but I think that’s normal.

There's only one other component I haven't tested, which is a temperature sensor.

In the motor specs it says it has 800W.

What do you think it could be? Do you think there’s any chance to repair the motor?

I'm not an expert, so I'd appreciate your answers weren't elaborately technical.


Thank you in advance.
 

Attachments

MaxHeadRoom

Joined Jul 18, 2013
25,469
A Universal motor will increase speed when the load is reduced or removed, IOW the lower the current through the series field will result in the higher speed.
Have you removed any fan etc?
 

Thread Starter

Patyome

Joined Jun 16, 2022
4
Hello, MaxHeadRoom!

Thanks for your reply.

I have removed the "fan thing" that produces the suction of the air (see attachment photos), but I don't believe the problem (much faster spin and louder noise) is there, since it started when all the pieces were "thigh together".
 

LowQCab

Joined Nov 6, 2012
2,171
The only way to increase the speed of a "Universal-Series-Motor", or, "AC/DC" type Brushed-Motor,
is to reduce the Load on the Motor.

Theoretically, with no Load, the Motor will "attempt" to increase RPM until it explodes,
( but in reality, other factors will limit the maximum possible RPM ).
.
.
.
 

MaxHeadRoom

Joined Jul 18, 2013
25,469
Hello, MaxHeadRoom!

I have removed the "fan thing" that produces the suction of the air (see attachment photos), but I don't believe the problem (much faster spin and louder noise) is there, since it started when all the pieces were "thigh together".
You remove the fan, you remove the load, Example, when you cover the end of a vacuum hose you hear the motor RPM increase drastically due to much less load.
.
 

Ramussons

Joined May 3, 2013
1,274
Hello, MaxHeadRoom!

Thanks for your reply.

I have removed the "fan thing" that produces the suction of the air (see attachment photos), but I don't believe the problem (much faster spin and louder noise) is there, since it started when all the pieces were "thigh together".
Are there air filters? If they are choked, the airflow will reduce and the motor will spin faster.
 

crutschow

Joined Mar 14, 2008
30,103
Sounds like some object is lodged somewhere in the air passages or hose reducing the air flow.
That will cause the motor to increase its speed.

Otherwise I see nothing in the motor that could change to increase its speed.
 

MaxHeadRoom

Joined Jul 18, 2013
25,469
One reason large DC motors with wound shunt fields used to have field-loss-detection, other wise if field loss occurred, the motor was capable of disintegrating at high RPM's :eek:
 
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