Vfd Retrofit On 2 Speed Motor

Dear All,

My customer has a 2 speed motor and he wants to retrofit a VFD on the motor. The application is mixer in polyvinyl industry. The motor details are as follows:

Make: Siemens
Model No: 1LA02230YK41
Frame: 225
Frequency Voltage Motor Connection Power Rating KW Current Rating A Speed RPM
50 415V Delta 38 68 1475
50 415V Star 45 80 2955

Im attaching the motor connection diagram. I have used a 45KW VFD with 90A rated current. I connected my VFD so that the motor remains permanently connected in Fast mode. When I try to start the motor, the speed does not rise above 1200 rpm and the current rises upto 103A. The VFD is not allowing the motor to further increase the speed as it is going in Maximum current. When I attach the motor in slow mode, the motor accelerates upto 1500rpm but again the current rises upto 103A.

Customer wants slow speed during the start for 2 minutes and then he wants to switch over to fast speed. Any ideas how can I succeed in retrofiting VFD in this application?

Regards,
Anurag

Centrifugal Compressor

Dear All,

I need some urgent help for selecting Softstarter for Centrifugal compressor application. Im attaching the load torque curve of the compressor. http://rapidshare.com/files/181073531/win6...Curve_50_Hz.pdf. Starting time required for the compressor is 5-12 seconds.

Motor details are AMbient temp = 45 deg c
Motor rating = 410 KW
Operating volt = 415 +/- 10%, 3 ph, 50 Hz +/- 3%
Full load current = 650 A

I have selected Emotron Softstarter of 500kw rating, 710A current with 300% overload for 30 sec. Will this be suitable for this compressor? How do we determine from the load torque curve of compressor, that it can be started with a softstarter? Presently he is using FCMA type starter and want to switch to SCR soft starter.

Regards,
Anurag

Softstarter Selection

Dear All,

I have an application of Reciprocating Gas compressor installed at a CNG gas filling station. Earlier we have installed soft starter on similar application and achieved starting current less than 200%. For my present application, customer has an existing Genset of 365kva installed. The details of genset are as below:

Alternator voltage: 415V
Alternator effi: 80%
Engine overload capacity: 110% for 1 hour every 24 hours
Alternator overload capacity: 110% for 1 hour every 24 hours

We have 2 3 phase motors of 160kw, 415V, 278A rated connected on this genset. The motors are presently started with Star Delta Starter. Inrush current kick goes upto 700-750A when the motor is started. Normal running current is around 200A. When the 1st motor is running, quite often it gets difficult to start the 2nd motor on the genset. We want to determine if by connecting the softstarter, we will be able to get the 2nd motor started while the 1st motor is already running.

If not by softstarter, is it possible by installing VFD on one of the motor.

Regards,
Anurag

Vsd Failure

Dear All,

We had installed a VFD for a rack and pinion hoist (passenger and material elevator in construction industry). The drive had inbuilt brake chopper and brake resistor was connected to it. Brake resistor had been mounted on top of the elevator. The drive was operating satisfactory for 2 days and on the 3rd day there was some smoke coming out from the resistor and the main breaker tripped. Once the supply was regiven customer tried to start drive twice but it didnt started. Later the drive was completely broken and there was no display. These events have been described by customer, so Im not sure if the drive was broken the first time itself when breaker tripped or it broke later when they tried to restart it.

The opened the resistor and found nothing burnt inside. They also checked the resistance and found OK. Im not sure if they properly did the continuity test. Later it was replaced by new spare VSD by the customer and as soon as they connected the brake resistor cable to the VSD, the main breaker tripped. That confirmed to them, that there is something wrong in resistor only. Later when our service engineer reached the site and opened the resistor, he found that one of the cable sleeve inside the resistor panel was cut and the cable was touching the body. Resistor manufacturer is explaining that the cable had not come with cut when delivered as the VSD has run without any problems for 2 days. Since there is vibration in the elevator, the inside panel acted like knife and cut the cable.

When new VSD was connected, the main breaker was tripping on earth fault as it was detecting cable touching with the body. During running when the cable touched body, the breaker tripped. Why did the 1st VFD got broken? It should have tripped on overcurrent or earth fault.

Regards,
Anurag

Welding Set

Dear All,

I have an application Welding Set, on which I have to install a VFD. Welding Set is 200kva 415V, 2 phase input. Power Supply is from Generator which has a 3 phase output. Presently without a VFD, the Welding Set creates unbalance load at the Generator. I think that if VFD is installed in between, the problem of unbalance load can be solved. My worry is that since only 2 phase output of VFD will be used, will the VFD trip on motor cable open at output?

Has anyone installed a VFD in such application?

Regards,
Anurag