An Incremental Approach to Modernizing a Paper Machine Drive System
Introduction. One of TMEIC GE’s valued customers is making significant investments in their paper machine. After a lot of analysis on how to modernize the drive system, a multi-phased approach was chosen. To further minimize risk and impact on production, maintenance outages are being used between phases to perform preliminary mounting of equipment, wiring, and initial validation.
At the completion of the project, the machine speed will go up 700 fpm and advance the drive system technology 20+ years. This article provides an overview of the 4 major phases and an in-depth description of phase 1.
The machine began production in the early 80s with a GE system that included 20 dc drives and featured:
- Load sharing field control packages on several drives
- Directo-Matic based master control
- Hardwired I/O between master control and system drives
- Hardwired operator devices on bench boards
The system has given the mill outstanding performance over the years. However, today’s technology can provide even more performance, with lower maintenance costs and better diagnostics. The multi-phased modernization plan is summarized in the table below and illustrated on the following page:
|Replace master control and operator interface system|
June - Oct 2005
|Replace DC paper roll motor drives with AC technology|
|Replace existing DC drive controls on larger frames|
|· Replace existing DC fan pump drive |
with a larger MV AC unit
· New press section DC drives
· New winder drives with a combination
of AC and DC drives
In several maintenance outages leading up to the primary outage for phase 1, the following work was performed:
- Mounted the new master controller in the space freed up with the removal of the spare legacy master controller. The controller was then wired, powered up, and connectivity established with each device it was to communicate with.
- Mounted, wired, and powered up all the remote I/O stations as well as validated communications with the new master controller.
- Pre-wired bench boards for color touch screen devices
- Provided formal training on the new master controller tools, in conjunction with the factory system test.
Four parts of Phase 1 Drive System Modernization Phase 1 replaced the master control and operator interface system. How this was done is discussed below.
1. Master Controller Retrofit. The existing drives, master controller, and operating station devices were all hardwired to one another. The new master controller and color touch screens supported several LAN options. However, the legacy drives that would remain until phase 4 could only be controlled with an I/O interface. Therefore, remote I/O stations were installed in the drive cabinets to interface between the new master control and drives (refer to figure below).
Master Controller Remote I/O Station in legacy Drive Cabinet
Paper machines commonly have three control systems that communicate with one another.
- A Programmable Logic Controller (PLC) that controls the sequencing of the motors and valves on the machine
- A Distributed Control System (DCS) that controls the chemistry of the paper machine
- And a coordinated drive system that regulates the speed and tension of the paper in the machine
The legacy system used hardwired I/O to I/O for communication between the three systems. The new master control changed this communication to a couple of commonly used industrial LANs that are far more flexible and accurate in the transmission of integer and floating point variables (refer to figure below). The openness of the VME architecture allows the master control to interface with virtually any industrial LAN by taking advantage of third party modules.
LAN interfaces with PLC and DCS systems
Editing and monitoring control logic in the new master control took a large step forward. The figure below illustrates the new features:
- Animated function block diagrams for editing and monitoring the control logic
- Both an outline and summary view of the logic for navigation
- Ethernet interface between the PC based toolbox and master controller
Dramatic Improvement in Configuration Tools
Additionally, the toolbox configures each of the new AC and DC drives being installed in phases 2, 3, and 4, providing one common tool for the entire coordinated drive system. Different devices are presented in a multi-document interface similar to MS-Excel’s ability to have multiple spreadsheets open simultaneously. There is also an integral trend window that supports the master controller and each of the system drives.
Toolbox Trend Window
2. Color Touch Screen Operator Interface. For the operators, the addition of powerful and flexible color touch screens at each bench board provided significant improvements in productivity:
- Presentation of more status data on the drives and process
- Provided the new function of operator controls for the upstream and downstream bench boards from any given station
- Flexibility to add/delete functions without any impact on the hardware
In a transition from hardwired operator devices to touch screen driven operator controls, performance and usability are critical. Factors that feed into these design metrics include:
- Repeated user review of the screen lay-out
- Touch screen hardware and operating system
- Communications protocol
- Master controller interface
HMI Selection. In this system, the Rockwell Panel View 1500 stations were chosen. This product is Windows CE based, a common theme being used by several vendors in today’s market. The Windows CE platform provides the level of infrastructure the touch screens need, such as communication and device drivers without all of the overhead or expense that a full Windows XP product brings.
The SRTP protocol was chosen for interfacing the Panel View 1500 stations with the master control over 100 MB Ethernet. The TCP and IP layers manage the encapsulation and transmission of data packets, ensuring that they all arrive and in the correct order. The SRTP portion of the protocol contains the data that is being requested or transmitted.
Including the Operators in the Screen Design. We have found that in order to have intuitive screens, it is essential to use the operators in the design process. They are the people most familiar with the machine and what functions are needed where. Thus, the operators were given three opportunities to review the design and provide feedback (refer to figure below).
This iterative process led to a set of screens the operators were familiar with and felt they were a part of designing. A sample screen is illustrated below.
Calender Drive Control Screen Functions
3. Factory System Test
To ensure smooth commissioning, an exhaustive factory system test was performed that included:
- Master controller
- All 14 Panel View touch screens
- VersaMax I/O station with Siltron drive hardwired interface
- ControlLogix PLC with interface to master control
- DCS system with interface to master control
- Extensive process modeling that allowed the team to “make paper” in system test
Additionally, the commissioning team, operators, and maintenance engineers were an integral part of the system test.
The commissioning of phase 1 was started months before the final maintenance outage where the bulk of the work was done. In numerous small maintenance outages leading up to the final outage for phase 1, the master control remote I/O stations were mounted and preliminary wiring done.
To further minimize the risks associated with the commissioning, key members of the factory design team followed the system out to the field, working along side the field team. Two teams worked 12-hour shifts over the course of 7 days to successfully commission the system, starting up on time with significant improvements in operation. Since this work, the machine has set several production records.
There are no “moon shots” (where everything happens at once) in the drive system business. Successfully modernizing large complex paper machines involves hundreds of small steps that include testing. This has been proven once again in this project.
John Hamby is Staff Marketing Engineer with TMEIC GE Automation Systems in Salem, Virginia
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