| Deregulation and consolidation of the rail system, and the need to ensure a
reliable, efficient grain handling system, has created a network of facilities that include the new generation of concrete high-throughput inland grain terminals.
Depending on output requirements, the grain terminals will operate up to 24 hours per day. Daytime activities include buying, receiving, storing and shipping grain, while the nighttime shift is kept busy cleaning and drying the grain. To achieve the increased loading quota requires the use of larger loading equipment, which
in turn requires specialized electrical and automation components to maximize productivity.
The Saskatchewan Wheat Pool (SWP) has embarked on a major expansion investment of more than $270 million, which includes plans to retrofit four existing grain elevators and build 18 new elevators by the year 2000. Long term plans will see operations expand even further with Saskatchewan Wheat Pools facilities and other joint ventures.
In 1988, Saskatchewan Wheat Pool replaced their relay
logic system with Modicon Compact 984 PLCs and have continually upgraded the older elevator systems to the latest available hardware (Quantum PLCs) and software platforms.
Complete electrical/automation system key to maximizing productivity
The control system chosen for the Saskatchewan Wheat Pool expansion had to meet specific criteria increased storage capacity, longer operating hours, and improved cycle times yet be reliable and easy to maintain. Equipment
manufacturers must provide a high level of service and expert technical/backup support. Manufacturer proximity to SWPs operations and their ability to provide a complete electrical/automation system were key
Multi-9 mini circuit breakers and Telemecanique LC1D contactors, LR2 overloads, terminal blocks and pushbuttons.
Telemecanique LT3 thermister relays improve motor protection and Square D definite purpose contactors are used for resistive loads. Electrical distribution
equipment includes Square D transformers and Federal Pioneer load centers and circuit breakers. In all of the 18 high throughput elevators, each motor has a Square D capacitor bank for power factor correction.
To reduce downtime on one of the bucket elevators, Schneider Canada suggested replacing the expensive and unreliable gear drive and full voltage, non-reversing motor starter with a simpler, less expensive gear drive and a softstarter. The softstarter allows for a ramped, smooth
start, which reduces mechanical stress on the machinery. The softstarters jog feature runs the elevator motor at 10% of its normal speed, which allows mechanics to check the buckets without causing the frequent downtime experienced with the original gear drive. The ability to soft start a motor is crucial to minimizing mechanical stress in a harsh environment that often reaches below -30C.
To facilitate preventive maintenance (and minimize the risk of machine overheating/failure),
Schneider Canada Services technicians have done infrared scans on SWPs older electrical equipment to identify hot spots, which indicate the presence of problems such as loose wiring connections.
Modicon Quantum PLCs will control all the new elevator terminal operations/processes (bucket elevators, conveyors, grain cleaning and drying). The PLCs will ensure consistent, reliable operation of the entire network of inland terminals, each of which has been designed in one of four
different configurations. To minimize downtime and maintenance costs, each of the terminals will run on a Modbus Plus Level 1 control network linked via Modbus modem to a single central supervisory control station in Regina. Existing Quantum installations will facilitate integration via Ethernet using TCP/IP of elevator facilities/process control systems and central accounting systems.
Square D fixed capacitors and PowerLogic energy management system will help SWP maximize energy
savings. The PowerLogic metering system will consist of PowerLogic 2450 circuit monitors which will feed energy usage information through analog I/O modules to the PLCs. Waveform, power factor, voltage and peak demand are captured on PowerLogic SMS 3000 software. An alarm installed in the circuit monitors will alert the local operator shortly before peak demand is reached.
Telemecanique TMD-2 motor control centers will operate all electrical processes in the elevator such as elevation,
cleaning, distribution, drying and weighing. Other Schneider Canada components will include Telemecanique starters and terminal blocks; contactors, overloads, relays and pushbuttons; and Federal Pioneer, Merlin Gerin and Telemecanique circuit breakers.
Customer benefit
Besides providing a system which minimized downtime and maintenance costs, Schneider Canada provides ready access to replacement parts and technical support. The proximity of Schneider Canadas manufacturing
operations and convenience of one supplier was a key benefit. "We were able to put a complete package together with the PLCs, MCCs and loose components, basically from one vendor. There is definitely an advantage there", says Willie Unger, Community Electric President.
Savings in energy demand for the first year of project Horizon (the 22 new sites) are forecasted at $145,000. Payback is forecasted at 10 months. SWP will save at least 50 KVA per site per month or 600 KVA per
site per year.
Written by Emily Cherneski, freelance writer
Edited by Louise Jones, Schneider Canada |
