VFD Voltages
VFD Voltages
(OP)
I am looking to find the best voltage for MOTOR-VFD solution at a 800-1000 kW. What is the Voltage trend worldwide for this power? 415 V, 690V or 11 kV.
Tanks
Peter
Tanks
Peter
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RE: VFD Voltages
At 415V you will have more choices available for both the drive and motor, but that is a lot of current at that voltage, so cooling becomes and issue for both.
690V seems to be the trend now in that size range. Still considered "low voltage" (as opposed to Medium Voltage) but the current is significantly lower than at 415V. Most of the major players in the VFD and Motor industry have products readily available in that range.
JRaef.com
"Engineers like to solve problems. If there are no problems handily available, they will create their own problems." Scott Adams
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RE: VFD Voltages
690V is a growing trend, especially in the pharma/chem industry. We have just released a Sic (silicon Carbide) based VFD for this market that incorporates sinewave filter. The investment is high to develop but the result is good and well matched for this developing market.
As jraef points out, MV @ 11kv is very expensive for drives below 1MW. Not impossible but you have to take into consideration the expertise and support issues if going this way.
So, not sure if there is a 'best voltage' as you have to be able to cope with all thrown at you. If physical size is important then the 690V design is worth looking at but you need to consider all the effects/precautions of running a motor with a VFD at this voltage.
RE: VFD Voltages
RE: VFD Voltages
Your compatriots at Siemens/Robicon have told me that although they market smaller, they really don't manufacture a MV VFD under 200A (about 2800kW at 11kV) because of the cost and minimum size of the components. So even if someone buys one with a nameplate that says 800kW, you really are paying for a 2800kW drive.
JRaef.com
"Engineers like to solve problems. If there are no problems handily available, they will create their own problems." Scott Adams
For the best use of Eng-Tips, please click here -> FAQ731-376
RE: VFD Voltages
RE: VFD Voltages
In the US and Canada, the company I work for has installed several VFDs on large ID fans in the range of 600hp-1500hp (450kW-1100kW) on 4160V. I'm guessing you're not in the US, as you stated the power requirements in kW rather than hp. We have also installed boiler feed water pumps in power plants at 6.9kV (they were 7000hp -- 5200kW).
RE: VFD Voltages
On the other hand, MV at these KW's is way too expensive. Probably best to use the highest available LV which, generally is 600V in North America and 690V many places elsewhere around the world.
RE: VFD Voltages
POP
RE: VFD Voltages
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: VFD Voltages
By his mentioning 415, 690 and 11kV he gave us a clue as to the fact that he is not in North America. 480V motors and a power source to run them are difficult to find outside of our little corner of the world. Good point otherwise though.
JRaef.com
"Engineers like to solve problems. If there are no problems handily available, they will create their own problems." Scott Adams
For the best use of Eng-Tips, please click here -> FAQ731-376
RE: VFD Voltages
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: VFD Voltages
RE: VFD Voltages
[quote]A large number of motors (maybe just IEC) are dual voltage 400/690V.
The IEC motors typically use 3 windings and offer dual voltages by either a star or delta connection. The voltage ratio is 1.73:1
NEMA motors use 6 windings and offer dual voltages by either a series or a parallel connection. There is a buried connection and the motors cannot be changed from the normal star to delta in the field. There are also some legacy delta motors with 3 buried connections.
The voltage ratio is 2:1
The connection diagrams for a twelve lead generator give a good overview. The diagrams with the windings in series are applicable to most IEC motors.
The diagrams with a star point are applicable to most NEMA motors.
As always, there are exceptions. Even this statement has exceptions.
respectfully