1. 1
Medium Voltage Presentation
MV VFD overview of the Toshiba andMV VFD overview of the Toshiba and
other Topologiesother Topologies
Abdou Barrow, EMA Inc.Abdou Barrow, EMA Inc.
www.emainc.netwww.emainc.net

2. 2
MV Variable Frequency
Drive (VFD)
Majority of MV VFDs are used on Pumps and Fans for energy savingsMajority of MV VFDs are used on Pumps and Fans for energy savings
and process control. Only 5% of all MV Motors are running on VFDs.and process control. Only 5% of all MV Motors are running on VFDs.
Just like LV VFDs, MV VFDs includes built-in overload protection (noJust like LV VFDs, MV VFDs includes built-in overload protection (no
heater elements required). Easily adjustable to the motor ratedheater elements required). Easily adjustable to the motor rated
current (Voltage Source).current (Voltage Source).
Adjusts both the frequencyAdjusts both the frequency
& voltage to the motor& voltage to the motor
Reduces the inrush current toReduces the inrush current to
115% (pumps and fans) of the115% (pumps and fans) of the
motor rated currentmotor rated current

3. 3
Variable Torque Loads
Flow is directly proportional
to speed.
Torque &Torque & Pressure is directly
proportional to the square of
the speed.
Horsepower is directly
proportional to the cube of
the speed.
(n1 )3
(n2 )3
HP1
HP2
=
(n1 )2
(n2 )2
P1
P2
=
The basic affinity laws can be converted for use with
centrifugal fans and pumps.
n1
n2
F1
F2
=

4. 4
 Current Source
• Older technology
• Uses an Active front end
• Use Choke to smoothen out the current ripples
• Cannot withstand accidental opening of the output contact, hence there is inherent
danger when VFD is used as sync bypass
• Has to be tune to a specific motor
 Voltage Source
• Newer technology
• Uses Buss capacitors to smoothen out the ripple voltage
• Will run smaller motor with minimal changes on the VFD settings
• More efficient
MV Topologies: Current
and Voltage Source

5. 5
• 24 Pulse Input Transformer
• Meets IEEE 519-1992 at PCC
• Input Voltage up to 15KV
• 2300, 3300, 4160 and 6600V
Motor Ratings
• 300 to 10,000HP
• Built to Maximize Personnel
Safety
Phase Shifting Transformer of T300MVi
Input Current Input Voltage
Standard Features on Toshiba

6. 6
24 Pulse Phase Shifting Transformer
 Improves line current wave and the load
power factor
 Independent secondary windings makes the
main circuits of the power cells relatively
isolated and it is low voltage on the
secondary side which mirrors low voltage
VFD, mature and proven technology
 The transformer is fitted with over
temperature protection
 The 24/36 pulses lowers the input harmonic
current to below IEEE519 specs at PCC
Standard Features on Toshiba

7. 7
Protections for VFD and personnel
 VFD comes with lightening arrestor on the primary of the phase
shifting transformer, Input Switch that is interlocked with the
input contactor and also current limiting fuses
Switch Fuse M13
MECH INTERLOCK
E
E
M1A
ACL
Lightning Arrestor
PT
T1
CPT
SH
Input Limiting
Current
Power
Main
Standard Features on Toshiba

8. 8
Fused Input Protects
Rectifiers-Non-standard
for others
460V Secondary For
Cooling Fan Power
24 Pulse Integral
Input Transformer
Three
Power
Cells
• Input Taps +/- 5%
• Over temperature
protection
U,
V,
W
Standard Features on Toshiba

9. 9
Power Cell Racks Out Clear of
Enclosure for Inspection / Removal
• Racking Mechanism,
Easy Module
Inspection
• Tin Plated Copper Low
Inductance Bus Structure
• 120V Connector & Fuses
Located at Bottom of Frame
• No Electrolytic Capacitors
Toshiba Topology
Power Section of T300MVi

10. 10
• Innovative Power Cell Topology
• Three Cell or Pole Design
• Medium Voltage 3300V IGBT’s
• Long Life Oil Filled
Bus Caps (20-30 years)
(not electrolytic)
• Connections
 Front
 Reduced MTTR
Toshiba Topology
Power Section of T300MVi

11. 11
. 5 Level Additive PWM
Output (@4160V)
• Neutral Point Clamp
 Use Existing or
Standard motors
• 1000 Ft Motor Lead
Lengths without dV/dT
Devices
• 2kHz Carrier Frequency.
Allows Heat Reduction
• IGBT’S rated at 3,300V
OUTPUT VOLTAGE
NO LOAD CURRENT
Toshiba Topology
Advantages of the 5 Level Topology

12. Step Three:
3600 Volts

13. 13
Others Topology
• 3 Level PWM Output
Less component count
Allows motor damage due to dV/dt without proper
filters
Allows insulation damage due to non NPC
Toshiba Topology
• 5 Level PWM Output with NPC
Allows us to run existing motors up to 1000ft with
no filters. No risks to damaging motor insulation
due to voltage spikes or cable insulations
Voltage Source Topologies
Comparison between 3 and 5 level
Topology

14. 14
3 Level Output
Waveform
5 Level
Output
Waveform
Comparison between 3 and 5 level
Topology

15. 15
T300MVi MV NEMA 1 Drive
Lightning
Arrestor-Protects
the rectifier section
from Surges
Visible
Disconnect
Vacuum Contactor Soft Charge
Circuit-Non standard for other
Inp Vacuum
Contactor
4160/120V
Potential
Transformer
50KAICFuses..Non
Standard for others
Switch
grounded
when open
Overall Lay Out of Toshiba
Topology

16. 16
Air Flow
Air
Flow
Air Flow
• Air Exit at Top
• Highly Reliable, Three
Phase 460V Fan Motors
• Redundant Fan Option
Available
• Aluminum Washable
Filter Screened Air
(NEMA 1G) Intake at
Bottom-Can be replaced
while VFD is running
Standard Features on Toshiba Topology

17. 17
 Transfer between drive and utility supply
 Synchronous transfer to utility up tp 4
motors (Bumpless)
 Synchronous transfer from utility
 Bypass switchgear and controls
 Manual VFD bypass
Bypass Options of Toshiba Topology

18. 18
T300MVi MV NEMA 1
Closed Transition: Bump-Less Transfer and Capture
A single-drive can be used
to accelerate multiple
motors to synchronous line
speed, minimizing drive
investment.
Bypass Options of Toshiba Topology

19. 19
• Graphical Display for
T300 and MTX
• Same Design as low
Voltage Toshiba Drive
• Intuitive Plain English
Commands
• Ethernet Data Port on
Front of Drive
ESCMON/PRG
User Friendly Keypad for Monitoring and Programming
T300MVi MV NEMA 1
Standard Features on Toshiba Topology

20. 20
Summary of IEEE-519 Conformity
Toshiba Allen-Bradley Siemens ABB Robicon
Internal
Transformer
Required at extra
cost
Required at extra
cost
Required at extra
cost
Internal
transformer
< 4% current
distortion (24 or
36 Pulses)
5 Level Topology
80-120% current
distortion – extra
cost to reduce
< 4% current
distortion for 24
pulse; ~ 13% for
12 pulse
3 level topology
~ 13% for 12 pulse
3 level topology
< 4% current
distortion
3 level topology
Internal control
power requires
only one source
Two sources
required
Two sources
required
Two sources
required
Two sources
required
Input visible
disconnect
Extra cost & size Extra cost & size Extra cost & size Extra cost & size
Lightning
Arrestor
Optional Optional Optional Optional
Small Footprint Larger Larger Larger Larger
MV IGBT GTO HV IGBT IEGT LV IGBT
Harmonics

21. 21
View on the MTX (NEMA 3R)View on the MTX (NEMA 3R)

22. 22
T300MVi MV NEMA 1
• Disconnect Switch?
• Fuses?
• Input vacuum contactor?
• Secondary sources of power?
• Drive capability to run on an existing power system.
• Is a power study necessary?
• Are standard cables acceptable to connect the drive?
• Is an existing or standard motor insulation acceptable for use on the drive?
Helpful Questions to qualify the right vendor before a purchase of MV
drives

23. 23
 Will the drive cause additional bearing shaft currents?
 Are motor stator RTD’s acceptable for use with the drive?
 Is the drive tuned to match the motor?
 Can it run smaller or different motors?
 What happens if the output is opened accidently?
 What happens if the output is grounded?
 What happens if the output is shorted?
T300MVi MV NEMA 1 and N3R Drive
N.B. Getting all these questions answered in writing will quickly
eliminate trouble after installation
Helpful Questions to qualify the right vendor before a purchase of MV
drives

24. 24
Synchronous Motors on Toshiba MV
drives !
• AC exciters provided by EMA/Toshiba
Houston
• Installed base of Synchronous Motors
 Water and Wastewater Market
Synchronous Motors
T300MVi MV NEMA 1