MH 1300 Water Pump: Single-Phase Motor Hums, Random Engine Start Issues & Capacitor Replacement

In the MH 1300 water pump, when the power is turned on, the engine buzzs from time to time and does not want to "start". Sometimes you need to turn it on 3 or 4 times to make it surprise. The problem is that the next few days work properly, and then a few times will not surprise. I checked connections and it's about key. I'm going to replace the capacitor - 25uF / 450V but I don't know if it will help. What could be another reason for a random engine start? I have several other single-phase motors and it has never been such a problem. I am asking for possible fault locations

Lewuski510 wrote:

I'm going to replace the capacitor - 25uF / 450V but I don't know if it will help.

Replace and check. The capacitor is responsible for starting the engine.

Before replacing the capacitor, measure its capacity, and first of all check the operation of the centrifugal switch, because it probably appears in this engine - there I would look for the cause of your "pain".

Read section 3.1.15 of the forum rules and correct the title in the first post!

Akrzy74 wrote:

Before replacing the capacitor, measure its capacity, and first of all check the operation of the centrifugal switch, because it probably appears in this engine - there I would look for the cause of your "pain".

There is no centrifugal switch, it is a motor with an auxiliary phase. Evidently a capacitor to be replaced - I used to do an autopsy out of curiosity, it turned out that the removal of one of the linings was "welded".

robokop wrote:

There is no centrifugal switch, it is a motor with an auxiliary phase

I wouldn't be so sure. However, if you are right - the author will confirm, I face.

http://www.omnigena.pl/obrazki/Mh1300%20nowy.pdf

Akrzy74 wrote:

I wouldn't be so sure. However, if you are right - the author will confirm, I face.

I disassembled several versions of these pumps - 2800rpm engine, with a capacitor of 10-20uF, depending on the power. The described symptoms actually in the case of a "civilized" engine would indicate a centrifugal switch, but there is no such. And as I wrote - a capacitor to replace, possibly a break in the winding - sometimes the aluminum winding is badly connected to the copper wire.

Thanks for the information. I contacted the company service and confirmed the lack of a centrifugal switch. The only thing that makes me wonder is that the engine humming can be unpredictable. For 2 - 3 days it's about the key, and the next time I need to turn on several times before it clicks. The service also could not (or did not want to) provide any specific information apparently this could also be due to voltage drops. In my case, the voltage does not drop below 215 V, i.e. within tolerance. They suggest delivering to the service but the randomness of failure causes that I have little hope that they will be able to identify the fault. For this reason, I am using the forum to try to eliminate this fault.

Lewuski510 wrote:

For 2 - 3 days it's about the key, and the next time I need to turn on several times before it clicks. The service also could not (or did not want to) provide any specific information apparently this could also be due to voltage drops. In my case, the voltage does not drop below 215 V, i.e. within tolerance. They suggest delivering to the service but the randomness of failure causes that I have little hope that they will be able to identify the fault.

Rather, deliver this pump to the service. This engine has a viciously low starting torque and any load on the shaft can prevent it from starting - even slightly rubbing the rotor on the body.

As suggested by some Internet users and after consulting a company from Toruń, I replaced the 25 uF starting capacitor and it's about key.