Frequency inverters
Home » Blog » Frequency inverters » DC link fault in 3 phase frequency inverter

DC link fault in 3 phase frequency inverter

Our one frequency inverter which drives 0.37 KW 400 V dosing pump motor intermittently (once in a month or once in two months) shows DC link fault and the speed is reduced to zero. This motor used to do changeover weakly. Pump NO: 1 never has such problem, pump NO: 2 only have this problem. We checked the motor found OK, checked the control circuit found ok, replaced with same new inverter still the same problem comes. We thought of incoming power supply problem so we swapped power supply cable from motor 1-2 but still the DC link fault comes in pump NO: 2. Then some of our experts said it is because the inductor is connected in the circuit, once remove the inductor this fault will not come again. But after removal of the inductor also same problem comes. From the previous history of work orders we found that this motor is a rewound motor, before rewinding there was no fault history at all. This motor is running always perfectly without any faults in manual control. Fault comes only in automatic control.
Could you please tell me what is the real problem?
Is it because of rewinding of the motor; winding geometry might have changed that affects the frequency inverter?
If this is the problem then why this fault is not coming whenever it is in service? (It waits for 1month or two months some time the fault comes in a weak also)
Is that the inverter will cause any problem because the inductor is in disconnected condition?
What is exactly the DC link fault and what are the reasons it can come in the inverter?
Why the DC link fault comes in when it is in automatic operation only?

Have you compared the good unit to the bad unit?
Could there be any mechanical issues loading the motor?
Check that the current level on the bad motor is the same as the good motor.
It sounds as if the rewind data is not correct and the motor is taking high current. If the rewind data is correct the core loss may be high.

The procedures you have gone through would indicate that the motor is the issue. My advice would be to go to the OEM and purchase a new motor or if it is a standard motor your regular supplier should be able to supply them. It could even be beneficial to purchase two new motors and keep the existing good one as a spare.

Post a Comment:

Calculate (1 + 4) =

You may also like:

In any electrical system, we limit the neutral grounding to 1 or 2 locations at the power source, eg, the star-points of generators or transformers. By keeping the grounded neutrals at the power source, earth ...
For 3 phase motor designs, there is hardly any slot combination that will yield a perfectly smooth torque-speed curve. Keeping the following rules in mind will (mostly) avoid the combinations that tend to ...
Koil can make the synthesis (i.e. design the winding layout from slot-pole combination) only for symmetrical windings. To have a symmetrical 3-phase winding the back EMFs must be equal and out of phase of 120 ...
There are many factors that govern the performance of rotary tube furnaces. A direct fired rotary unit has a potential for much higher thermal efficiency due to the direct contact of the hot gases with the ...
Hazardous area classification has three basic components: Class (1,2) : Type of combustible material (Gas or Dust) Div (I, II) : Probability of combustible material being present Gas Group (A,B,C,D): most ...
Gozuk Service Gozuk Blog: all about electric motor control & drives industries development in energy saving applications.


Like pumps, fans consume significant electrical energy while serving several applications. In many plants, the VFDs (variable ... energy consumedA frequency inverter controls AC motor speed. The frequency inverter converts the fixed supply frequency (60 Hz) to a ... Motor starter (also known as soft starter, motor soft starter) is a electronic device integrates soft start, soft stop, ... Soft starter allows the output voltage decreases gradually to achieve soft stop, in order to protect the equipment. Such as the ... Soft Starter reduces electric motor starting current to 2-4 times during motor start up, reduces the impact to power grid during ...

In Discussion