The software was developed on the AB logix family of controllers (ControlLogix, CompactLogix) While any PLC can be used, the software was designed and written to take advantage of the special features available with this platform. This minimizes rewriting of software and utilizes a library of proven logic routines. For the end user, this minimizes, if not eliminates on site software debug time which is often a thorn in the start of any startup making it ready to run out of the box.

Features

Recipe Controlled Burner Management

Most ovens have the ability to over-bake. This is mainly because it is easier to build in extra capacity at the manufacturing stage than it is to retrofit burners later. While this is a catch all for most situations, if this spare burner capacity is not managed correctly, it can create and contribute to poor product quality. Excess heating capacity will readily burn product. On mild bakes, low fire alone may still increase the baking temperatures, especially if a low fire of 3-4" cannot be maintained. This creates a situation where burners are switched off in an attempt to maintain set point. This then removes the "live" heat creating an in balance in color and bake. The oven is now oscillating out of control and the product will reflect this. The optimum position for a burner is between 20-40% open and modulating which creates the, often overlooked "live" heat needed for stability.
To accommodate this heat management, we provide burner patterning within our recipes. As many recipes as you desire, all contain the ability to select or deselect burners. So when changing products, perhaps only 80% of the burners are used. This makes each burner work harder to maintain the bake temperature and consequently modulate around its set point yielding a more efficient flame, less heat overrun and better stoppage survivability.

Product Tracking

All oven control systems come equipped with product tracking, not an invisible concept but a fully visible insight to what is going off within the oven. This feature will be the operator's best friend. It can work with the control "active product tracking" or simply be a window in the production process "passive product tracking" It can be enabled or disabled at will. The design is primarily to work with recipe changeovers and reduce the mean time between differing products. As a product enters the oven, the product is tracked down the length and through the zones. By knowing where the product is within the oven allows us to change the zone temperature only when necessary. Legacy systems accept a new recipe, which updates the oven instantly. Just one look at the screens will indicate exactly where the product changeover is, how far down the oven the product is and when it is due out. Using this insight you can control how the oven reacts and feed forward the product so we can react anticipating change instead of waiting for the long time lag to react.
Waiting for the oven to react to a gap or leading product edge is the biggest cause of flash heat and damaged product. In feed forward mode, we can not only prevent this but stabilize core temperatures too.

PIDE (PID Enhanced)

The new series of microprocessors from Allen Bradley2 support a new type of PID instruction. PIDE uses a velocity type algorithm rather than a speed algorithm, thus adding the long overdue response to process heat latencies and deviations. The difference being that the new instruction takes care of latencies within a temperature controlled process loop better by a incorporating a delta-T time function. The upshot is more stable control and better reaction to changing workloads.
Each zone also houses a pressure transducer. This is fed back into the PLC and displayed for visual indication as well as being fed back into the PIDE control. The pressure feedback is used to enable absolute minimum flame settings as well as optimum and consistent control between all zones. The range of pressures achievable can be easily clamped if needed but the main advantage is by ensuring the active valve range is optimized with no latent spots, valve-lag is virtually eliminated. Once again this increases the PIDE performance and enhances control.

Progressive Cutback

Another feature of our control is progressive cutback. If a zone runs away with the temperature (there could be a product gap) the zones may enter cutback. Cutback occurs when the actual temperature exceeds the set point by a pre-determine amount. To counter this, a small percentage of burners will be disabled.

Gap Control (Patent Pending)

Within the last year we partnered with a bakery in researching the absolute minimum changeover times and gap control. The results far exceeded anything we imagined. Using this method of control we eliminated flash heat and no matter how big or small a gap down the oven was, be it 4 shelf lengths or half of an oven, the last row before the gap and the first after the gap, not only had the same color but had identical core temperatures. There simply was no difference and it was as though there was in fact no gap at all.


HMI

Main Screen

The main HMI screen is key to the operation. It must be easy to understand, easy to navigate and self explanatory.