Cost Effective Upgrade of Obsolete Electronics

Transcription

1 of Obsolete Electronics Barry W. Wiles Industry Manager Crane Systems Avtron Manufacturing Inc E. Pleasant Valley Rd. Independence, OH Phone: (216) FAX: (216) Key words: SCR Firing, DC Drive Upgrade, Dockside Crane, Retrofit INTRODUCTION Electronic component obsolescence has created issues for many ports throughout the world. Mergers and acquisitions have driven control/automation companies to consolidate product lines and obsolete drive hardware. New products are generally not backward compatible. This has created challenges for port maintenance departments in obtaining spare parts, service personnel familiar with the equipment and dependable operation. As ports experience continued growth, more pressure is placed on the cranes to stay in production and reduce bottlenecks. Problem In 1993, Jacksonville Port Authority purchased two new IMPSA cranes for its Talleyrand facility. Cranes were furnished with GE control systems. A Series Six programmable logic controller (PLC) handled the I/O while DC 300 DC drives ran the motors. Both systems are now obsolete. A proprietary network connected the PLC and DC drives together offering little flexibility for upgrading the system in pieces. As the system aged, when problems arose they caused more and more down time on the cranes. Both the PLC and DC drives are obsolete and are no longer supported by the manufacturer. Due to the obsolescence, spare parts became scarce and more expensive. Service personnel, trained in the older systems, were also hard to find or unavailable. Jacksonville Port Authority (JAXPORT) felt it was at risk of losing one of these vital cranes for a prolonged period of time if an upgraded system was not installed. Well aware of this threat, JAXPORT became proactive on finding a solution. A project team was assembled to analyze different solutions to the problem. As the project developed, several key project goals were set. 1. Replace the Series Six PLC 2. Install a SLC-500 PLC platform similar to those already in use at the port. 3. Retrofit or replace the obsolete DC300 drives. 4. Install a high level diagnostic system similar to those in use on other cranes at the facility. 5. Select a proven technology that has been installed in other ports. 6. Eliminate the exposure of the port to downtime due to obsolete electrical parts. 7. Minimize the downtime exposure to operations for installation of the project. 8. Install a system that can be maintained by the ports personnel. Page No. 1

2 Solution JAXPORT S first order of business was to review drive suppliers and the technology available for their retrofit. Product review meetings were held with many manufacturers to determine the best approach to the problem. JAXPORT wanted a system that was easy to maintain and provided flexibility. A key point was the use of a SLC-500 based PLC system because JAXPORT had this type of PLC throughout the port and had extensive training and experience in its upkeep and use. They felt that this platform could be easily supported by their people. As vendors were reviewed and their capability was explored Avtron s drive system upgrade was chosen due to its ease of use, flexibility and diagnostic capabilities. BACKGROUND Jacksonville Port Authority originally installed IMPSA No.1 and 2 in Each crane was provided with a General Electric control system. A series Six PLC ran all of the I/O on the crane. DC300 DC drives controlled the motors. As the years pressed on, equipment became hard to maintain and eventually obsolete. Control of the crane was broken down into three individual motions allowing the crane to Hoist, Gantry and Trolley at the same time. Hoist and Gantry sections were supplied with their own DC drives while the Trolley and Boom shared one. Although the drive control boards and associated hardware were obsolete, the SCR s and associated power components were still supported by several vendors. The Series Six PLC system had been discontinued as well. Some boards could still be repaired but new modules were no longer available. This posed the greatest threat to the port because the PLC was at the heart of the crane control system. Figure 1 IMPSA 1 Unloading First Box after Upgrade Page No. 2

3 PROJECT SCOPE JAXPORT evaluated several different approaches to the upgrade of the cranes. One of the key points was the type of PLC JAXPORT wanted to use. Although several companies could retrofit the controls, only Avtron was will to design the system with the PLC platform desired. Avtron also offered a retrofit package that would leave the SCR s in place and replace the obsolete electronics, minimizing the overall cost of the upgrade. On the Trolley/Boom section, a new drive was used due to the small size of the power bridge. Avtron also presented several successful references to the customer demonstrating to the JAXPORT that the hardware was industry proven. System Layout Crane controls were located in the main electrical house of the crane. Three DC drives provided power conversion for the crane and provided the following functions: Drive No.1 = Hoist, Drive No.2 = Gantry and Drive No.3 = Trolley/Boom. Motor and drive ratings are listed below: Section Name HP VDC ADC Motor RPM Hoist Motor No HP /2000 RPM Hoist Motor No HP /2000 RPM Gantry Motor No.1 35 HP RPM Gantry Motor No.2 35 HP RPM Gantry Motor No.3 35 HP RPM Gantry Motor No.4 35 HP RPM Gantry Motor No.5 35 HP RPM Gantry Motor No.6 35 HP RPM Gantry Motor No.7 35 HP RPM Gantry Motor No.8 35 HP RPM Trolley No.1 65 HP RPM Trolley No.2 65 HP RPM Boom Hoist 125 HP RPM Table I Motor Specifications Motors were fed from three DC drives with the following arrangements Rated ADC Rated VDC Overload Rating Drive Name Hoist % Gantry % Trolley % Table II Drive Specifications Page No. 3

4 Drive Retrofit Solution Many factors go into determining whether a motion is a candidate for retrofitting the SCR s or not. A typical rule of thumb is that sections rated 250HP and above can typically be upgraded economically. Key factors in this decision include: 1. Drive size and complexity. Drive HP size is a key factor in determining a retrofit path. If the HP is small, it is generally easier to replace the drive with a new unit. Experience has shown that 250HP is typically a breaking point depending on the situation and complexity of the system. Typical crane applications utilize drives for multiple motions and are generally more complicated systems. 2. Are the SCR s still commercially available? In most cases, the semiconductor devices will still be available for a particular drive. Manufacturers have used standard sizes over the years which are still produced and supported. SCR s are installed in a heat sink assembly and are readily accessible. Part of Avtron s solution is to survey the drives prior to a solution proposal to determine the best upgrade path. 3. SCR firing type. Almost all crane drive systems use a picket-fence type firing circuit for the SCR s. Modern day SCR s are designed to fire by this approach. Most cranes that are retrofit candidates are less than 20 years old. There are some types of older technology where SCR s are fired by a single hard pulse which is known as Hard Pulse firing. It is important that this not be overlooked when deciding to upgrade the electronics on the drive. You must determine the firing is compatible with the device for the solution to be viable. 4. Drive Location and accessibility Another key issue in retrofitting an existing DC drive is its location and accessibility. In most cases, it is easier to retrofit the SCR s than replace the entire drive. Removing the entire drive unit may require additional wiring because the power terminals are not in the same location. It will generally also require large amounts of re-wiring to existing components that support the drive. Manufacturers will typically provide entire new panels with the support devices included which adds cost and installation time. 5. Customers goals and objectives A final review is with the customer to determine their goals and objectives. In most cases, the customer is looking to eliminate obsolete equipment with newer equipment that will be maintained and supported for several years. Schedule is also important and can dictate a solution path. If the schedule is aggressive, retrofitting the SCR s takes less time and can get the crane back into operation quicker. Economics also proves that retrofitting the SCR s is less costly than replacing entire units. Page No. 4

5 When evaluating the retrofit project, several issues help direct JAXPORT the best value for the upgrade. 1. The Hoist drive was rated at 1800 Amps DC which is a strong candidate for retrofits. 2. The Gantry DC drive was rated at 1200 Amps DC which is also a strong candidate for an upgrade. 3. Trolley/Boom drive was rated at 280 ADC which is smaller and could easily be replaced by a stand-alone drive. 4. SCR s for the Hoist and Gantry drives were still readily available and cost affective to obtain. 5. JAXPORT had a preference for a SLC-500 based PLC platform. Hoist and Gantry Drive Retrofit Details JAXPORT evaluated both retrofit and full replacement of the drive control system. In its evaluation, proven technology was a key element in their final decision. JAXPORT decided to select the retrofit solution offered by Avtron. The system consists of an Advanced Firing Module (AFM), sense board and a bridge interface board. A typical configuration is shown in the following figure: Figure 2 Typical retrofit system diagram Page No. 5

6 The larger Hoist and Gantry drives SCR s were in excellent shape and commercially available. Drive electronics were located on the front of the drive making replacement easy. A standard DC300 retrofit kit replaced the electronics of the drive as shown in the figure below. Figure 3 Existing DC Hoist controller Before (Left) and after (Right) retrofit DC contactors and associated power hardware were also in good working order. These components were left in place to reduce the amount of work and time required for the upgrade. The retrofit package also included a built-in motor field supply that eliminated the original external unit. An integrated motor field supply optimizes the performance of the hoist by providing field control at an optimum speed. Trolley/Boom Retrofit Details Due to its smaller size, the Trolley/Boom drive was replaced in its entirety. Two motors were connected in series to control the trolley and a single motor controlled the Boom. Two separate field supplies provided the shunt fields with excitation. A single DC drive controls each motor. Contactors and power equipment were all in good working order. Avtron provided a new DC drive with a built-in field supply for the Trolley. Having an integrated supply provides optimum performance and control of the motor field. An external field supply was provided for the Boom motor because it operates only occasionally. Page No. 6

7 Figure 4 Trolley/Boom Drive before (Left), Trolley/Boom after (Right) Programmable Logic Controller Replacement JAXPORT wanted a PLC package that utilized the spare parts already in stores. They also wanted to reduce the learning curve on the new crane control system by using a PLC platform that was familiar to their technicians. A plan was implemented that replaced the existing distributed PLC I/O throughout the crane. Figure 5 Existing PLC (Left), New PLC (Right) Page No. 7

8 Figure 6 Gantry Leg I/O before (Left), and after (Right) Installation time and costs were also reduced by re-using existing field wiring for the input and outputs devices on the cranes. To achieve this, a new PLC rack was put in place of the outdated PLC. Field wiring was then re-terminated into similar I/O locations on the PLC. Where field I/O resided, new blocks were put in place and re-terminated. All existing wiring was re-used saving installation time and cost for the project. A fiber-optic link was originally used between the electrical house PLC and cab I/O. A large converter module (Top of picture in Figure 5) was located at each location to convert the fiber-optic communications to a serial protocol recognized by the PLC. A smaller, PLC based converter module was used to achieve the same operation in a smaller footprint. An Ethernet communication system tied to control system together. An Ethernet communication module was provided on each of the Avtron drives, PLC and and HMI. The Avtron drives utilized a fiber-optic communication link. This eliminates noise issues seen with copper based systems in drive control systems. A fiber-optic communication channel can also achieve higher data rates and throughput. A managed switch connects the drives, PLC and human interface terminals together on a single network. The Ethernet backbone also provides JAXPORT with a flexible network that can be expanded in the future. Avtron s ADDvantage-32 drive hardware supports several standard control vendor protocols to connect and communicate to devices, eliminating proprietary networks. This protects the customer s investment and allows third party devices to utilize the networks information. Diagnostics Another major component of the upgrade was the installation of a Crane Management System. With only a few cranes at the terminal, it is imperative that the cranes be available for opertaion as close to 100% as possible. When problems do arise, they must be addressed quickly and efficiently. JAXPORT purchased and installed as part of the upgrade, Avtron s CraneWin CMS package. CraneWin allows port personnel to graphically troubleshoot problems and determine issues quickly. System alarms, Page No. 8

9 running information and warnings are all archived by the system for thirty days allowing long-range history and data. Crane diagnostics are presented in a graphical and tabular format to make operation easy. Each screen has active areas that allow the user to drill down into the next level of diagnostics. Screens are designed to not only provide easy navigation, but also show vital information on operation and faults. At the top level is the home screen. This provides a graphical overview of the entire crane. Active areas are highlighted with blue borders. Should a fault condition arise, the area containing the fault will flash red showing the user where to immediately go to obtain information. If a particular component failure occurred on a system panel somewhere in the electrical room, the e- house area would blink red. Touching this area on the screen opens the electrical house floor plan as seen in the figure to the right. Each piece of electrical equipment including motors, power distribution, drives, etc. are all shown exactly how they are positioned in the crane. The failed device will then cause its particular enclosure or area to blink red telling the user to press that area for further investigation. Touching the enclosure area will then expose the panel detail. All control panels located in the enclosure are shown graphically for the user. In cases where there are multiple panels each panel is shown. The troubled area will once again be blinking red to assist the user in determining where to move next. If multiple components were faulty on different panels, each panel would blink red that had failures. Selecting the blinking panel will present to the user all components on the panel in a graphical format. Panels may have additional data details about them along with their components. Once again, the faulty device will be flashing red telling the user the exact cause of the failure. From here, it is easy to set a course of action that can be taken to rectify the problem and put the crane back into operation. This troubleshooting and diagnostic methodology significantly reduces mean-time to-repair when a failure occurs on a crane. CraneWin provides a central point for the troubleshooting and diagnostic monitoring of the entire electrical system. CraneWin also provides an archived list of Faults and alarms that are stored for a thirty day period. Trend screens are also available that store data for the same amount of time. CraneWin archives drawing databases, manuals and other information that can be used to help troubleshoot and monitor the crane. CraneWin is designed to get the crane back into operation in fifteen minutes or less depending on the failed device. CONCLUSION Jacksonville Port Authority evaluated many different companies and products for the upgrade of the two IMPSA cranes at Talleyrand. They have demonstrated that upgrading an existing, obsolete control system on a crane can result in state-of-the-art operation without the cost of performing a complete replacement of the control. Careful evaluation of the existing system by a qualified vendor can yield significant performance improvements obsolete control equipment. Adding a strong backbone of Page No. 9

10 communications can also enhance the diagnostic capabilities which would not be available in older, less capable controls. Page No. 10