Pennine Intelligent Drive Control System
Air chiller conveyor systems in poultry processing facilities can be several kilometres long and consist of a number of linked AC drives. A standard system – usually operating on an open loop control – relies upon the chain tensioners and slip within the drives to maintain control.
As the chillers become larger, with a greater number of drive units, controlling the tension becomes more difficult; overall line tension needs to be increased to ensure reliable operation.
However, as increasing the line tension causes premature wear on the chain and the conveyor parts, it is very important to have the drives and tension units correctly positioned and controlled.
At Pennine, we have extensive knowledge of the operation of multiple drive systems, gained from years of on-site experience. We’ve found that the best way to control a multiple drive system is to control the tension between each drive, and so we’ve developed our own solution: the Pennine Intelligent Drive Control (PIDC).
- The PIDC can be retro-fitted to any existing conveyor
- It is not restricted by the number of drives on the system
- Each drive is controlled by its own frequency inverter
- Inverter speed is regulated from a common PLC
- Increases conveyor reliability
- Reduces wear on conveyor parts
- Reduces downtime
- Extends chain life
- Can be remotely monitored on PC
- Extends maintenance intervals
How it works
Spring-loaded tension unit
A spring-loaded tension unit is usually fitted after each drive. These tension units have linear position sensors fitted to them which measure the compression of the spring and each tensioner can be set to a desired setpoint.
The analogue signal taken from the tensioners is fed into the PLC. The algorithm in the PLC program decides which drives require a speed trim and the amount, maintaining a set tension between each drive.
The speed variations are normally less than 1Hz from one drive to the next and are unnoticeable on the line during production; the overall line speed is also not affected.
For the system to operate efficiently, we take into account both chain stretch due to wear and temperature changes on start-up.
Using a weighted take-up unit - a long tensioner with a weight on the end – to anchor the system, any excess chain in the line is stored or taken from here as required.
The take-up unit is also fitted with a linear position sensor, which is read into the PLC to give an indication of its movement and an alarm will sound when it reaches its maximum or minimum travel.
The PLC not only monitors and records the movement of the tensioners, but also monitors and records drive speeds/drive torques and line speed - all useful when diagnosing problems.