Rockwell Automation Medium Voltage Drives Unit: Helmke - Crusher
Rockwell Automation Medium Voltage Drives Unit: Helmke - Crusher
Rockwell Automation Medium Voltage Drives Unit: Helmke - Crusher
Rockwell Automation
Medium Voltage Drives Unit
Helmke – Crusher
RA Order No. 7012776
Prepared By:
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TABLE OF CONTENTS
SCOPE ................................................................................................................................................. 4
CRUSHER CONTROL.......................................................................................................................... 5
Drive Load (Torque) Sharing Control .................................................................................................................................................. 5
Drive Modes of Operation .................................................................................................................................................................... 6
Reduced Capacity ................................................................................................................................................................................. 7
MSR (Motor Safety Relay) ................................................................................................................................................................... 7
Stop Command ...................................................................................................................................................................................... 8
ControlLogix Summary of User-Adjustable Tags .............................................................................................................................. 10
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REVISION HISTORY
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SCOPE
This document is intended to define the interface for the PAC program included
with the VFD (Variable Frequency Drive) used for Crusher drive/motor load sharing
control. Included is:
SYSTEM HARDWARE
The Programmable Automation Controller processor used for drive control in this
project is a 1756-L61 from the ControlLogix family. The basic functions of the PAC are
to handle drive loadsharing functions and the interface between the Drive PAC and the
System Control.
The ControlLogix rack contains connects the drives through a 1756-CNB
ControlNet bridge module, to the System control through a 1756-ENBT Ethernet IP
module, and to local operator devices via hardwired I/O modules.
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CRUSHER CONTROL
The Crusher motors are mechanically coupled to the same load, and are
required to share the load (torque) evenly under normal machine operating conditions.
To handle this, VFD #1 has its Torque Control Mode (parameter 90) set to 1
which selects the speed regulator output, and VFD #2 Torque Control Mode is set to
mode 3, which selects the smallest value between the ‘Torque Command External’ and
its own speed regulator output. The ‘Torque Command External’ value which is sent to
VFD #2, is set equal to VFD #1 speed regulator output value.
VFD #2 is commanded to run at a speed slightly faster than VFD #1, which
places VFD #2 speed regulator into saturation and forces VFD #2 to use the positive
torque limit being sent via the ‘Torque Command External’ parameter.
If the torque limit being sent to the drive is too high, causing a speed greater than
the drive speed reference, then the speed regulator output value will be lower than the
torque limit being sent and be the value the drive uses, thereby preventing an
overspeed condition.
4160V 50Hz
4160V
Variable
frequency
Crusher Motor 1
PF 7000 PF 7000
Master Slave
4160V
Variable
frequency
Crusher Motor 2
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Normal/Test Operation
Local/Remote Operation
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Reduced Capacity
There is no provision in the Drive System to operate with only one motor. There
are no Drive Output Contactors to electrically isolate a Drive from a motor and therefore
both Drives must be operating in order to run the crusher.
An MSR relay is supplied for the Drive System. When the MSR is tripped it
removes Medium Voltage power from all drives by opening the Drive input contactors.
This results in the motors coasting.
Each Drive has an Emergency Stop pushbutton wired in series in the MSR trip
string. Also, terminal blocks are provided for the client to wire into the trip string of the
MSR relay.
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Stop Command
The Crusher Stop Command must be set high (closed contact from the client’s
control system) to enable the Drive System and allow a Start to occur. If the stop
command is low (0), it will stop the crusher using the ‘Normal Stop’ deceleration ramp.
At the end of the Ramp, when the actual speed is equal to or less than the value in
ControlLogix tag z_VFD_SHUTOFF_FREQ , the Drives stop controlling the motors.
Normal Ramp Stop uses Deceleration Profile1 in the Drive. Some of the settings which
affect Deceleration Profile1 are in ControlLogix tags, and others are in Drive parameters
as shown in the following table.
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The following list of tags are from the ControlLogix program. The as-shipped
values are shown; these may change during commissioning.
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NETWORK OVERVIEW
Networks
There are two networks used in this system; ControlNet and Ethernet IP.
ControlNet Network
Ethernet IP Network
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Communication between the VFD PAC and the Crusher System Control can be
accomplished using a produced and consumed message via the Ethernet IP module in
each PAC. Communication information for each PAC (required for the ControlLogix
Programs) is as follows (note that highlighted values are required from end user):
Depending on the message content and purpose, the update time and content
sizes may be different. If produced/consumed messaging is used, then the messages
should be set as follows:
Update
Message Tag Name Size Purpose of Message
Time
MSG_FROM_VFD_PAC 20ms DINT[40] Drive System Status Information
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The VFD PAC produced messages tag is in a DINT array data type as detailed
below.
Communication between the Crusher PAC and the Client’s System PAC can also
be done using message (MSG) instructions in the Client’s System PAC. The message
instructions need to be a CIP Data Table Read message targeting the same tag name
mentioned in the producer-consumer messaging description.
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The Drive PAC is not configured to receive any commands from the client’s
controller via the Ethernet/IP connection. Control of the Drive System is performed via
hardwired signals.
Status signals that the Drive PAC makes available for the Client’s Control
System are as follows:
continued
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MSG_FROM_VFD_PAC[15]-[39] Spare
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ENGINEERING REFERENCE
All 20-COMM-C adapters will have the logic command/status word and all
datalinks enabled for drive communication purposes. The datalinks on each drive are
set with the following parameters.
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20-COMM-C Parameters
Unless the adapter parameters are mentioned below, they are set to their default
values. All 20-COMM-C adapters require the settings listed below.
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The External fault parameters in the each drive are listed below. These require
the following settings in conjunction with the PAC program. The PLC is also taking an
appropriate action for each of the ‘Warning’ conditions in the following table.
Bit 4 set to 1
All 175 DPI Loss Mask
(Adapter 5 loss will cause a fault)
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60 seconds
S-curve deceleration profile1 time.
(used for ‘Normal Ramp’ stop) This
value sets the time that it would take
All 479 S-curve deceleration 1 time to ramp from full speed to zero speed
using a linear ramp. The actual ramp
time will be increased by the
percentage specified in parameter
475 (S-curve percent).
60 seconds
S-curve acceleration profile1 time.
(used for ‘Normal’ mode acceleration)
This value sets the time that it would
All 481 S-curve acceleration 1 time take to ramp from zero speed to full
speed using a linear ramp. The
actual ramp time will be increased by
the percentage specified in parameter
475 (S-curve percent).
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The following list of drive parameters are compared by the ControlLogix program
to ensure that they have been set the same in all drives. This is to ensure that the
speed reference ramps are the same in all drives, which is critical for any drive which
could take over as the Master Speed Regulator. Also the settings for Encoder feedback
must be the same for all drives in the system. Parameter 475 (S-Curve percent) is
controlled by the ControlLogix program and is always set the same in all drives.
If the parameters are not matched then a ‘Normal Ramp Stop’ is triggered, and a
Drive warning is also triggered as annunciation of the cause Stop.
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