Variable Speed drive application 2

[irishpaul]

I am currently working on the design of a chemical injection skid for offshore use. We have designed the unit to run from a 400V 50Hz supply. There are two motors on this unit. These are coupled to geared pumps. My client has now stated that the unit should run from the following supplies:
400V 50Hz
400V 60Hz
450V 50Hz
450V 60Hz

The pumps cannot operate at the higher speed.
The motors are EExde, 55kW

Would a VSD overcome this operation by setting it so it always outputs 400V 50Hz? The on board PLC on the skids will provide a volt-free contact to start and stop the pump.
I have not used VSDs before so any advice would be most welcome

 

[iNCiSiVe]

Most VSD's are able to take a wide variety of supplies.

I have used AB drives extensively on machines for export. Though you do need to program into the drive what the input voltage will be. It still works if you don't it just incorrectly scales the speed.

 

[irishpaul]

Cheers Incisive

So if i get this correct:
I connect my three phase incoming supply, what ever it may be and manually set the output at the VSD control panel? So as long as the procedures to do this are outline all should be ok?

 

[iNCiSiVe]

Yes... Though you will need to change the settings for the input voltage as well

 

[jraef]

That is correct ONLY if the output voltage that you settle on is the lower of the two. The VFD cannot create voltage, so you cannot have it provide 450V from a 400V input. I know that is not what you said you wanted to do, but I thought you should be clear on that minor point.

Also, if the pumps need to turn on independantly of one another, each one will need to have its own VFD. You can use one VFD as a sigle power source, but then everything connected to it must be started and stopped by the VFD all at the same time.

"Venditori de oleum-vipera non vigere excordis populi"

 

[irishpaul]

Jaref,

I intend to use two drives. I spoke to ABB Drives who say that their ACS 800 500V series is suitable. I always want to put a 400V 50Hz supply out so as such I will never be using it to generate a 440V supply. Am I correct?

 

[jraef]

Yes, that will work fine, as long as you use the 500V rated drive. In your setup, program the maximum output voltage to be 400V and the frequency at maximum voltage to be 50Hz. I don't know the specific parameters to set on an ABB drive, but I know they will be on the list somewhere. With those settings, the VFD will give that output no matter what happens on the input side.

Think of a VFD as being a new power source that you get to program as to voltage and frequency. Incoming power is nothing more than the "raw material" feeding the new power source. As long as that raw material meets basic requirements such as minimum voltage (in your case 400V) and adequate current availability, it will produce whatever you tell it to.

Just as a comment, the ACS-800 might be a bit of an overkill if you are not going to use it to change the motor speed at all. Nothing wrong with the drive, but it is designed for much more complex and demading applications. If all you want is a variable input power source, you could likely do much better economically. Then again, if your end user is comfortable with ABB and uses them elsewhere on his platform, it may be a good idea from a familiarity standpoint.

"Venditori de oleum-vipera non vigere excordis populi"

 

[irishpaul]

I spoke with ABB drives yesterday and it turns out I have to use an ACS 800 and change my motor to a six pole. This is due to the large start up torque of the pump. Also it has to be an ACS 800 due to the fact that the motor is an EExde motor for use in Zone 1 IIB T3.

Thanks for the info