Motor rotation

hi, i face new problem and confuse about motor rotation. around 3 month my machine running, suddenly 1 motor pump rotate to anti-clockwise. suppose it rotate in clockwise. why this matter can happen without touch and disturb the system. thanks for ur cooperation

This should not happen if the motor is three-phase. If single phase, the start winding may be defective.

Please advise if single phase or not.

I have heard denials from a maintenance tech after he was troubleshooting a motor system. He didn't check for rotation after meggering and reconnecting the motor. See if any recent troubleshooting evolutions have occured.

najib.danial said:

hi, i face new problem and confuse about motor rotation. around 3 month my machine running, suddenly 1 motor pump rotate to anti-clockwise. suppose it rotate in clockwise. why this matter can happen without touch and disturb the system. thanks for ur cooperation

Click to expand...

Just a shot in the dark. If the load can cause the motor to spin backwards, perhaps it's single phasing and the backward spin from the load is giving it a direction.

milldrone said:

Just a shot in the dark. If the load can cause the motor to spin backwards, perhaps it's single phasing and the backward spin from the load is giving it a direction.

Click to expand...

I saw a hydraulic pump do that once. After a maintenance shutdown Cletus left a 3-way ball valve in the wrong position so the motor was being driven backwards by fluid back flowing through the pump from the mispositioned valve. When Bubba attempted to start the motor it blew the line fuses. The motor continued to be driven backwards. Bubba saw that the contactor was pulled in but that the motor was turning the wrong direction. They were baffled because they knew they hadn't touched the electrical.

najib.danial said:

hi, i face new problem and confuse about motor rotation. around 3 month my machine running, suddenly 1 motor pump rotate to anti-clockwise. suppose it rotate in clockwise. why this matter can happen without touch and disturb the system. thanks for ur cooperation

Click to expand...

please clarify first, is it a three phase or a single phase?...if single phase and still running but in counter clockwise, so please check the starting capacitor.. just suggesting maybe can help...

jingo

HELLO NAJIB
1- if your motor is 3 phase then check the phase sequence because in 3 phase motor if you change the position of one phase the motor will rotate to the opposite direction.
2-if your motor is single phase so please chech the start capacitor.
i hope this will help you

Alaric said:

I saw a hydraulic pump do that once. After a maintenance shutdown Cletus left a 3-way ball valve in the wrong position so the motor was being driven backwards by fluid back flowing through the pump from the mispositioned valve. When Bubba attempted to start the motor it blew the line fuses. The motor continued to be driven backwards. Bubba saw that the contactor was pulled in but that the motor was turning the wrong direction. They were baffled because they knew they hadn't touched the electrical.

Click to expand...

Now that was a great visual!!!

If I'm not mistaken, you can make a 3-phase motor do the same without touching the electrical.
Should one winding be damaged/broken, the motor will start vibrating. The slightest push in either direction will cause the motor to run in that direction.

Alaric said:

I saw a hydraulic pump do that once. After a maintenance shutdown Cletus left a 3-way ball valve in the wrong position so the motor was being driven backwards by fluid back flowing through the pump from the mispositioned valve. When Bubba attempted to start the motor it blew the line fuses. The motor continued to be driven backwards. Bubba saw that the contactor was pulled in but that the motor was turning the wrong direction. They were baffled because they knew they hadn't touched the electrical.

Click to expand...

Excellent example!

Alaric you rule but...

When Bubba attempted to start the motor it blew the line fuses. The motor continued to be driven backwards.

Click to expand...

How does a motor run with no power? Cold fusion has not happened yet. Unless the flow continued to make the backwards drive.
Love you.

SMOKE said:

Alaric you rule but...
How does a motor run with no power? Cold fusion has not happened yet. Unless the flow continued to make the backwards drive.
Love you.

Click to expand...

The fluid going through the pump was spinning the motor

Yea, I was walking to bed when I realized the point, and came back. I feel so silly.

Why [can] this matter happen, without touching and disturbing the system?

Click to expand...

It is important to know that the "system" consists of all devices between the pump motor and the main incoming utility power lines. I saw a similar incident once at a remote river pumping station. Maintenance swore that none of the equipment at the pumping station had been touched recently, but the pump started running backwards. Further checking revealed that a transformer at an upstream substation had been replaced recently. The phases got shifted when the new transformer was reconnected.

That reminds me of another "swapped phase" incident. The shop foreman called me out and told me that the overhead crane (an old 1940 C&H 10-ton unit) had just crashed into the wall and almost knocked a hole in it. He wanted me to check out the travel limit switch. I asked what had been done recently. He said that they replaced the East-West Travel motor, but he said that none of the limit switch wiring was changed. I looked at the wiring diagram and realized that if the motor was rotating in the opposite direction than before, that the limits would no longer stop the crane. That turned out to be the problem. Switching two of the motor phase wires solved the problem. Afterward, the foreman came up and said "You know, I wondered why the travel buttons were reversed after we swapped that motor..." I was thankful that no one was hurt.

thanks for the infomation. fyi,our motor is 3-phase. inside control panel have 3-phase sequence component but it not function, are coz of it? how to check 3-phase sequence? are use multimeter?