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#23202 - 03/13/03 12:06 AM Three-phase boost transformer  
haitijim  Offline
Junior Member
Joined: Mar 2003
Posts: 4
Apex, NC USA
I have a motor that is designed for non-US power. It expects 380 volts, three-phase (with 220 volts phase-to-neutral). Feed is 220 volts three-phase Delta. Power is 3 KVA. Can anyone recommend a source for a boost transformer?


Work Gear for Electricians and the Trades

#23203 - 03/13/03 12:51 AM Re: Three-phase boost transformer  
Bjarney  Offline
Moderator
Joined: Apr 2002
Posts: 2,527
West-Southern Inner-Northeast ...
See: http://www.federalpacific.com/literature/drytrans/FPTS-RTB-0701.pdf About a dozen pages in is a good reference for figuring size and connection of buck/boost transformers. Operating 50Hz motors on 60Hz power may not always work too well. In some cases, it may be easier to change the motor.


#23204 - 03/14/03 10:29 PM Re: Three-phase boost transformer  
Scott35  Offline

Broom Pusher and
Member
Joined: Oct 2000
Posts: 2,707
Anaheim, CA. USA
haitijim,

You might not be able to use a simple Voltage Boosting Autotransformer setup for this situation, since the available Voltage is 220 VAC, and your Motor needs 380 VAC.

The only "Booster" setup would require a Secondary Voltage of at least 160 VAC.

In this situation, you may need to just settle for a normal Isolated Transformer (Primary and Secondary not connected as an Autotransformer), and adjust output via "% Voltage Taps".

Please reply if you would like additional information, or more web sites for Transformer Manufacturers.

Scott35 S.E.T.


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!

#23205 - 03/15/03 01:15 PM Re: Three-phase boost transformer  
C-H  Offline
Member
Joined: Sep 2002
Posts: 1,497
Stockholm, Sweden
Can the motor be reconfigured for delta operation (220V phase-to-phase)? It's possible on some European motors.


#23206 - 03/15/03 03:03 PM Re: Three-phase boost transformer  
Scott35  Offline

Broom Pusher and
Member
Joined: Oct 2000
Posts: 2,707
Anaheim, CA. USA
Great suggestion, C-H!!!
If the windings can be connected as a Delta (currently Wye), this should drop the required input voltage from 380 VAC to 220 VAC (219.3995...VAC to be exact).

If the Motor doesn't mind an increased input voltage of between 4% (230 VAC) and 8% (240 VAC), then no boost transformer would be needed!

Another thought:
Does this Motor have Split Windings? (AKA Dual Voltage Motor).
Find this either on the nameplate, or by verifying if there are 9 Motor lead terminations.
Typical 3Ø Squirrel Cage Induction Motors for 60Hz US stuff would be connected as follows (for a Wye connection of stator coils, each split coil in series - or setup for Higher rated voltage):

T-1 to "1",
T-2 to "2",
T-3 to "3",
"4" to "7",
"5" to "8",
"6" to "9"

Scott35


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!

#23207 - 03/15/03 03:10 PM Re: Three-phase boost transformer  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
I used to work at an Amusement park and our German rides had motors of that configuration.

When I started they were running at 208 volts but they were dogs trying to accelerate the rides so we used buck boosts to get the voltage to 230 and all was good.

[This message has been edited by iwire (edited 03-15-2003).]


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#23208 - 03/15/03 04:11 PM Re: Three-phase boost transformer  
haitijim  Offline
Junior Member
Joined: Mar 2003
Posts: 4
Apex, NC USA
Thanks to all who have responded. My motor is made in The Netherlands and has this on nameplate:
Mfg. = Overveld
Type 4PT090L
Volts: 220/380
1.5 KW
1410 RPM
6.9/4 amps
0.77 PF
IP = 54

My power source measures 220 volts phase-to-phase and 127 volts phase-to-neutral.

The motor has 6 leads. Label says it can be connected Delta or Wye. I thought this means:
-If connected as Delta, 380 volts phase-to-phase should be used as power source.
-If connected as Wye, 220 volts Phase-to-neutral should be used as the power source.

Since 380 volts/sqrt(3) = 220 volts, could I use three single-phase, 1:1 transformers with each primary connected from phase-to-phase of my source and the secondaries connected as 220 volts Wye. If I understand the nameplate voltage rating correctly, this should work. I realize there is an issue with motor speed, but that is not critical in the application.

I would appreciate any enlightenment. Haitijim


#23209 - 03/15/03 10:30 PM Re: Three-phase boost transformer  
zapped208  Offline
Member
Joined: Feb 2003
Posts: 196
Somewhere in USA
Haitijim- Try this connection, Delta, L1-U1 & W2, L2-V1 & U2, L3- W1 & V2. This should work at 220 / 3 phase . Are your leads make like this?


Shoot first, apologize later.....maybe

#23210 - 03/16/03 02:09 AM Re: Three-phase boost transformer  
Scott35  Offline

Broom Pusher and
Member
Joined: Oct 2000
Posts: 2,707
Anaheim, CA. USA
haitijim,

Quote

Volts: 220/380
1.5 KW
1410 RPM
6.9/4 amps
0.77 PF
IP = 54


Cool! You do not need any Transformers (unless your AC system is a 4 wire Wye system and the Motor needs exact voltage).

Connect the Motor leads for the lower rated Voltage (220 VAC), and drive the Motor directly from your 3Ø System.

Must be a 50 Hz 4 pole Motor, judging from the 1410 RPMs! On 60Hz, this Motor will run at 1725 RPMs @ Full Load output.

Like that Power Factor of 77%!

The FLA figure of 6.9 Amps is what the Motor would draw at 220 VAC-50Hz, when 1.5 KW is drawn from the supply (and the output HP = 2 HP).

Quote

My power source measures 220 volts phase-to-phase and 127 volts phase-to-neutral.


No problem! The grounded Neutral Conductor is not used here - only the 3 Ungrounded Conductors (ØA, ØB and ØC).

Before I go any farther, are you reading 220 VAC on a DVM? Are you sure this system is 220 VAC and is 3Ø?
If so, you would find the following readings between Line and Ground (or Neutral):

ØA to Ground / Neutral: 120 VAC (+/- 5%),
ØB to Ground / Neutral: 208 VAC (+/- 5%),
ØC to Ground / Neutral: 120 VAC (+/- 5%),


If all three are 120 VAC to ground, you have a 4 wire Wye - with 208 VAC across the Ungrounded Conductors (ØA-ØB=208 VAC, ØB-ØC=208 VAC, ØA-ØC=208 VAC). In this case, you may want to boost the voltage up another 12 VAC, via an Open Delta booster configuration of two 250 VA Transformers.

If you only have 1Ø 3W service, you are out of luck! [Linked Image]

Scott35


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!

#23211 - 03/16/03 10:50 AM Re: Three-phase boost transformer  
C-H  Offline
Member
Joined: Sep 2002
Posts: 1,497
Stockholm, Sweden
Quote

Before I go any farther, are you reading 220 VAC on a DVM? Are you sure this system is 220 VAC and is 3Ø?
If so, you would find the following readings between Line and Ground (or Neutral):

ØA to Ground / Neutral: 120 VAC (+/- 5%),
ØB to Ground / Neutral: 208 VAC (+/- 5%),
ØC to Ground / Neutral: 120 VAC (+/- 5%),


Scott, the 127/220V wye is the old European system which still is in use in some parts of the world. (Mainly Brazil) Your suggested readings would apply to a 240V center tapped delta system.


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