PowerFlex 7000 Medium Voltage AC Drive Liquid-Cooled
("C" Frame) - ForGe Control
Publication 7000L-UM301D-EN-P
Important User Information
IMPORTANT
Read this document and the documents listed in the additional resources section about installation, configuration, and
operation of this equipment before you install, configure, operate, or maintain this product. Users are required to
familiarize themselves with installation and wiring instructions in addition to requirements of all applicable codes, laws,
and standards.
Activities including installation, adjustments, putting into service, use, assembly, disassembly, and maintenance are required
to be carried out by suitably trained personnel in accordance with applicable code of practice.
If this equipment is used in a manner not specified by the manufacturer, the protection provided by the equipment may be
impaired.
In no event will Rockwell Automation, Inc. be responsible or liable for indirect or consequential damages resulting from the
use or application of this equipment.
The examples and diagrams in this manual are included solely for illustrative purposes. Because of the many variables and
requirements associated with any particular installation, Rockwell Automation, Inc. cannot assume responsibility or
liability for actual use based on the examples and diagrams.
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Inc., is prohibited.
Throughout this manual, when necessary, we use notes to make you aware of safety considerations.
WARNING: Identifies information about practices or circumstances that can cause an explosion in a hazardous environment,
which may lead to personal injury or death, property damage, or economic loss.
ATTENTION: Identifies information about practices or circumstances that can lead to personal injury or death, property
damage, or economic loss. Attentions help you identify a hazard, avoid a hazard, and recognize the consequence.
Identifies information that is critical for successful application and understanding of the product.
Labels may also be on or inside the equipment to provide specific precautions.
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voltage may be present.
BURN HAZARD: Labels may be on or inside the equipment, for example, a drive or motor, to alert people that surfaces may
reach dangerous temperatures.
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Trademarks not belonging to Rockwell Automation are property of their respective companies.
This manual contains new and updated information.
Summary of Changes
New and Updated
Information
This table summarizes the changes made to this revision.
Top icPag e
Changed all references of “tachometer” to “encoder”Throughout
Added HPTC information to Topology section17
Updated Speed Regulator Bandwidth24
Updated Torque Regulator Bandwidth24
Inserted Torque Accuracy with HPTC24
Added Polish to list of available Languages25
Added “Dual-port Ethernet/IP” to Communications Protocols25
Replaced Control Overview block diagram29
Added “Pipe Materials and Layout” section76
Added dimensions and torque information to Pipe Flange detail images77
Inserted “External Piping to the Drive” section77
Inserted “Controlled Siphon into Open-top Reservoir” section78
14Rockwell Automation Publication 7000L-UM301D-EN-P - June 2014
Overview of Drive
Chapter 1
Introduction
The PowerFlex® 7000 represents the third generation of medium voltage drives at
Rockwell Automation. The PowerFlex 7000 medium voltage AC drive is part of
the PowerFlex family of AC drive products. The Allen-Bradley PowerFlex® family
of Drives incorporates leading-edge technology, embedded communications, and
significant commonality across multiple platforms, networks, operator interface
programming and hardware. Designed for end users, solution providers and
OEMs, PowerFlex 7000 liquid-cooled drives meet applications ranging from
3000...9000 horsepower (2240...6715 kW).
The PowerFlex 7000L is a general purpose stand alone medium voltage drive that
controls speed, torque, direction, starting, and stopping of standard
asynchronous or synchronous AC motors. It is intended for use on a host of
standard and specialty applications such as fans, pumps, compressors, mixers,
conveyors, kilns, fan-pumps, and test stands. Primary industries for these
applications include petrochemical, cement, mining and metals, forest products,
power generation, and water / waste water.
The PowerFlex 7000L is a global product that adheres to the most common
standards from NEC, IEC, NEMA, UL, and CSA. It is available with the world’s
most common supply voltages at medium voltage, from 2400...6600 volts.
The design focus is on high reliability, ease of use, and lower total cost of
ownership.
(1)
Liquid Cooling
The PowerFlex 7000L “C” Frame liquid-cooled drive utilizes a closed loop
system to cool the converter main power components and the integral DC link
inductor.
Benefits of Liquid Cooling Include:
• Smaller drive dimension compared to air-cooled drives of similar rating
• Higher power rating capability
• Quiet operation in control room
• Low loss rejection to the control room reduces air conditioner loading
• Majority of losses rejected outside the control room via a liquid-to-air or
liquid-to-liquid type heat exchanger
(1) For 2400V and 3300V designs, contact factory.
Rockwell Automation Publication 7000L-UM301D-EN-P - June 201415
Chapter 1Overview of Drive
Benefits of the 7000L “C” Frame Liquid-cooled Drive:
• Higher power rating capability (up to 9000 hp / 6715 kW)
• 18 Pulse and AFE rectifiers for low harmonic solutions that meet IEEE
519-1992 Harmonic Guidelines
• Motor friendly current and voltage output waveforms for use with
standard new and existing motors
– Inverter duty motors not required
– Motor temperature derating not required
– No additional dv/dt or peak voltage stress to motor insulation system
– Tested up to 15 kilometers (9.3 miles) cable distance between drive and
motor
• Spacious cable termination cabinet for ease of use by installation
contractor
• Cable termination stabs accommodate:
– 3 cables in / 3 cables out (Direct-to-Drive or AFE rectifier)
– 9 cables in / 3 cables out (18 Pulse)
– Top or bottom entry and exit of line and load cables
• 90% of drive losses are rejected outside the control room
• Integral liquid-cooled DC link inductor reduces overall dimension and
eliminates external interwiring.
• Integral pumping panel includes:
– Line supply c/w disconnect and fusing
– Closed loop coolant system
– Iron and chloride free liquid ethyl-glycol / deionized water mixture
3
– Low conductivity coolant (1-2 micro-Siemens / cm
– Isolated from medium voltage
– Fully serviceable low voltage compartment isolated from medium
voltage power
– Monitors coolant temperature, flow, level, conductivity, and pressure
– Redundant pumping system (optional)
– Automatic pump change over on pump failure
– 1/2 turn valves with quick disconnect couplers for pump replacement
when drive is operating
– Full drip tray to contain any spilled coolant
– Drain and fill pump for convenient filling
– Industrial schedule 80 CPVC piping for pump panel, headers and
manifolds (no condensation possibility)
– Control hardware for cycling of main / redundant cooling pumps and
heat exchanger fans
• “Plug and play” Power Cage concept
– Central location for easy access to all main power components
)
16Rockwell Automation Publication 7000L-UM301D-EN-P - June 2014
Overview of DriveChapter 1
2U (X1)
2V (X2)
2W (X3)
SGCT’s
LINE CONVERTER
DC LINK
L+
M+
SGCT’s
MACHINE CONVERTER
U (T1)
V (T2)
W (T3)
L-
M-
1U
1V
1W
LR
– Common modular design for rectifier / inverter
– Same concept as air-cooled drive for front access, easy component
replacement, and no special tools
– 5...10 minutes to replace main power devices
– No need to remove any cooling lines for device replacement
– Reduced manufacturing time for faster delivery and lower cost
•Keyed mechanical interlock
– Interlocked with main disconnect means to prevent unsafe access to
medium voltage section
Topology
The PowerFlex 7000L utilizes a Pulse Width Modulated (PWM) – Current
Source Inverter (CSI) for the machine side converter as shown in Figure 1
. This
topology offers a simple, reliable, cost effective power structure that is easy to
apply to a wide voltage and power range. The power semiconductor switches
used are easy-to-series for any medium voltage level. Semiconductor fuses are not
required for the power structure due to the current limiting DC link inductor.
With 6500VPIV rated power semiconductor devices, the number of inverter
components is kept to a minimum. For example, only six inverter switching
devices are required at 2400V, 12 at 3300-4160V, and 18 at 6600V.
The PowerFlex 7000L has the additional benefit of inherent regenerative braking
for applications where the load is overhauling the motor (i.e. downhill conveyors,
etc.), or where high inertia loads (i.e. fans, etc.) need to be slowed down quickly.
Symmetrical Gate Commutated Thyristors (SGCTs) are used for machine
converter switches. Silicon-controlled rectifiers (SCRs) (for 18 Pulse) or SGCTs
(for AFE rectifiers) are used for the line converter switches. An AFE
configuration is shown in Figure 1
.
The PowerFlex 7000L provides a selectable option for enhanced torque control
capabilities and increased dynamic control performance. This High Performance
Torque Control (HPTC) feature delivers 100% torque at zero speed and
provides torque control through zero speed with smooth direction transition.
Figure 1 - AFE Rectifier (4160 Volt)
Rockwell Automation Publication 7000L-UM301D-EN-P - June 201417
Chapter 1Overview of Drive
Line
current
Line-to-line
voltage at PCC
Rectifier Designs
There are two offered designs for the rectifier of the PowerFlex 7000L drive.
18 Pulse Rectifier
An 18 Pulse phase controlled rectifier is shown in Figure 2. In an 18 Pulse
configuration, the IEEE 519-1992 requirements are met in the majority of cases
without the need for passive filters; however, a multi-winding isolation
transformer is required to mitigate the low order harmonics by phase shifting
principles. The 18 Pulse solution is superior to 6- or 12-pulse offerings in terms of
lowering line side harmonics.
Isolation transformers are available in indoor dry type, cast coil, and outdoor oilfilled designs for maximum flexibility in dealing with floor space, installation
costs, and control room air conditioner loading. (Refer to Specification 80001005, Rectifier Duty Transformers, for more details on transformer requirements
and features.)
Sample line current and voltage are also shown in Figure 2
current is approximately 5.6%, while the THD of line voltage (line-to-line) is
approximately 2.0%. (THD of line voltage is a function of system impedance.)
The 18 Pulse rectifier consists of one master bridge and two slave bridges and will
always have a total of 18 SCR switching devices.
. The THD of line
Figure 2 - 18 Pulse Rectifier and its input waveforms
Active Front End (AFE Rectifier)
An active front end (AFE rectifier) suitable for the PowerFlex 7000L topology is
also commonly called a PWM rectifier. This is particularly attractive since it does
not require an isolation transformer to meet IEEE 519-1992. Most available
technologies in today’s MV market require a multi-winding transformer to
mitigate the unwanted harmonics by phase shifting the transformer secondary
windings. Depending on the topology, the transformer can have up to 15 sets of
secondary windings. Elimination of the isolation transformer reduces capital and
installation costs, saves on valuable floor space, and increases overall system
efficiency.
18Rockwell Automation Publication 7000L-UM301D-EN-P - June 2014
Overview of DriveChapter 1
Line
current
Line-to-line
voltage at PCC
The AFE rectifier requires a switching pattern that complies with similar rules as
the inverter. The pattern, used for the example shown in Figure 3
, is a 42-pulse
selective harmonic elimination (SHE) pattern, which eliminates the 5th, 7th and
11th harmonics. The integral input capacitors are designed to reduce the current
harmonics of the higher order. The filter transfer function technique is used to
place the filter break frequency in a region where no harmonics are present. This
prevents the excitation of system harmonic frequencies. Other factors that are
considered when designing the filter are the input power factor and the
requirement on Total Harmonic Distortion (THD) of input current and voltage
waveforms.
The AFE rectifier is ideal when a distribution transformer is required to step
down the distribution voltage to match the VFD and motor voltage. The rectifier
input current, the rectifier terminal voltage and the line current and voltage
waveforms are shown in Figure 3
. The line current THD is approximately 4.5%,
while line-to-line voltage THD is approximately 1.5%. (THD of line voltage is a
function of system impedance.) Input power factor with the AFE rectifier is
equal to or greater than 0.98 for the typical speed and load range when applied to
variable torque loads.
Figure 3 - Active rectifier (PWM) and its input current/voltage waveforms
“Direct-to-Drive” Technology
The PowerFlex 7000L with “Direct-to-Drive” technology allows you to:
• connect supply power directly to the drive without an Isolation
Tr a n s f o r m e r
• connect a new or existing motor directly to the drive without extra motor
filtering.
Most Medium Voltage Drive Manufacturers use multi-winding isolation
transformers to mitigate unwanted harmonics by phase shifting the transformer
secondary windings. Depending on the topology, the transformer can have up to
15 sets of secondary windings. The disadvantages to this method are the high
degree of drive and transformer complexity, a very high component count and
many interconnecting cables and connection points. This leads to much higher
maintenance requirements and lower reliability.
Rockwell Automation Publication 7000L-UM301D-EN-P - June 201419
Chapter 1Overview of Drive
Manufacturers also use isolation transformers to protect motors from Common
Mode Voltage stress. When transformers are used they allow the motor neutral
point to be connected to ground, but with this method, the common mode
voltage that would otherwise be impressed on the motor is impressed on the
transformer. The disadvantage to this method is that increased transformer
insulation and increased cable insulation is required between the transformer and
the drive so it can withstand the common mode voltage stress.
Rather than use an Isolation Transformer, the “Direct-to-Drive” Active Front
End uses the semiconductor switching pattern to reduce line current harmonics
to levels that comply to the world’s most accepted harmonic standards. The
Active Front End is the best method of harmonic cancellation because it does not
suffer from complexity and high component count like multi-pulse drive
topologies do.
“Direct-to-Drive” technology produces virtually no common mode voltage so it
is suitable for new or existing motors and imposes no stress on the drive input.
The advantage of “Direct-to-Drive” technology over an Isolation Transformer is
that no extra insulation is required in the motor, in the motor cables or in the line
cables.
In addition to mitigating Common Mode Voltage, “Direct-to-Drive” technology
mitigates dv/dt or Reflected Wave Voltage Stress on motors.
The simplicity of its design results in a lower initial capital investment, lower
operating cost, lower installation cost and lower maintenance cost relative to
drives that require isolation transformers.
The PowerFlex 7000L with “Direct-to-Drive” technology is typically smaller and
lighter than drive technologies that use Isolation Transformers. Isolation
Transformers represent 30 to 50% of a drive system size and 50 to 70% of the
system’s weight. This means that there is no interwiring between drive and
transformer (for external transformer configurations). This makes the PowerFlex
7000L the simplest to install.
20Rockwell Automation Publication 7000L-UM301D-EN-P - June 2014
Overview of DriveChapter 1
200.00
100.00
0.00
-100.00
-200.00
-300.00
10.00K
7.50K
5.00K
2.50K
0.00K
-2.50K
-5.00K
-7.50K
-10.00K
100.00
110.00
120.00130.00
)
140.00
150.00
Arms
Vrms
Motor
Current
Motor
Voltage
Motor Compatibility
The PowerFlex 7000L achieves near sinusoidal current and voltage waveforms to
the motor, resulting in no significant additional heating or insulation stress.
Temperature rise in the motor connected to the VFD is typically 3°C (5.5°F)
higher compared to across the line operation. Dv/dt in the voltage waveform is
less than 10 volts / microsecond. The peak voltage that the motor insulation will
see is the rated motor RMS voltage divided by 0.707. Reflected wave and dv/dt
issues often associated with VSI (voltage source inverter) drives are a non-issue
with the PowerFlex 7000L. Typical motor waveforms are shown in Figure 4
.
These motor friendly waveforms are achieved by utilizing a selective harmonic
elimination (SHE) pattern in the inverter to eliminate major order harmonics, in
conjunction with a small output capacitor (integral to the drive) to eliminate
harmonics at higher speeds.
Standard motors are compatible without derating, even on retrofit applications.
Motor cable distance is virtually unlimited. This technology has been tested,
controlling motors up to 15 km (9.3 miles) away from the drive.
Figure 4 - Motor waveforms @ full load, full speed
300.00
TIME (ms
Rockwell Automation Publication 7000L-UM301D-EN-P - June 201421
Chapter 1Overview of Drive
SGCT Features and Benefits
An SGCT is a Symmetrical Gate Commutated Thyristor with an integrated gate
drive. Positioning the gate drive close to the SGCT as shown in Figure 5
low inductance path that provides more efficient and uniform gating of the
device. As a result, the device is better suited than a conventional GTO to handle
the fluctuating levels of voltage and current while it is switching on and off during
gating.
An SGCT has similar characteristics to an IGCT (used on some VSI drives),
including low conduction and switching losses, low failure rate, and double sided
cooling for low thermal stress. However, the SGCT achieves voltage blocking
capability in both forward and reverse directions up to 6500 volts by a NPT
(N
on-Punch-Through) structure and nearly symmetrical pnp transistor in the
wafer, while the current is unidirectional. Unlike many VSI topologies that use
IGBTs, the semiconductors used in the PowerFlex 7000L feature a non-rupture,
non-arc failure mode. In the unlikely event of a device failure, the fault would be
contained within the device.
Implementing SGCTs in the PowerFlex 7000L “B” Frame results in significant
advantages including:
1. Simplification of the snubber design and a reduction in the size of the
snubber capacitor by a factor of 10.
, creates a
2. Operation at a higher switching frequency (420-540 Hz), hence reducing
the size of passive components (DC link inductor and motor filter cap) by
50%.
3. Improving performance of the drive.
4. Reduction of component count, hence improving reliability, cost, and size
of the drive.
5. Fail safe failure mode (non-rupture).
Figure 5 - SGCT with integrated gate drive (left) and unit cell structure (right)
22Rockwell Automation Publication 7000L-UM301D-EN-P - June 2014
Specifications
Overview of DriveChapter 1
Table 1 - General Design Specifications
Description
Motor Type Induction or Synchronous
Input Voltage Rating2400V, 3300V, 4160V, 6600V
Input Voltage Tolerance± 10% of Nominal
Volt age Sag
Control Power Loss Ride-through5 Cycles (Std)
Input Protection
Input Frequency50/60 Hz, +/- 0.2%
Power Bus Input Short-circuit
Current Withstand (2400…6600V
Basic Impulse Level
Power Bus DesignCopper - Tin plated
Ground BusCopper - Tin plated 6 x 51 mm (¼ x 2 in.)
Customer Control Wire WaySeparate and Isolated
Input Power Circuit Protection
Output Voltage0…2400V
Inverter DesignPWM
Inverter SwitchSGCT
Inverter Switch Failure ModeNon-rupture, Non-arc
Inverter Switch Failure Rate (FIT)100 per 1 Billion Hours Operation
The method of control in the PowerFlex 7000 “C” Frame medium voltage AC
drive is called sensorless direct vector control, meaning that the stator current is
divided into torque producing and flux producing components, allowing the
motor torque to be changed quickly without affecting motor flux. This method
of control is used without encoder feedback for applications requiring
continuous operation above 6 Hz and less than 100% starting torque.
Full vector control can also be achieved with encoder feedback for applications
requiring continuous operation down to 0.2 Hz with up to 150% starting torque.
Vector control offers superior performance over volts/hertz type drives. The
speed bandwidth range is 5...25 rad/s, while the torque bandwidth range is
15...50 rad/s.
The control hardware includes a processor board (DPM) with an interface to six
fiber optic boards (depending on the voltage and number of switching devices)
via OIBB, an analog conditioning board (ACB) and an external IO board (XIO).
The control hardware is used for rectifier and inverter, induction or synchronous
drive control and the two rectifier types (18 Pulse or Active Front End).
The DPM features two floating point DSPs (Digital Signal Processor) and a
FPGA (Field Programmable Gate Array) for advanced functions such as gating
and diagnostics, fault handling and drive synchronization control.
Figure 11 - Control Hardware Layout for PowerFlex 7000 “C” Frame
OIBBOIBB
30Rockwell Automation Publication 7000L-UM301D-EN-P - June 2014
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