You can see by the first photograph that the original heater and controls was well past it’s best. This is a glorified fan oven and the 1950’s vintage fixed speed centrifugal fan blew air through a heater box fitted with old style domestic oven heating elements.
The heated air was blown into an oven cabinet about a meter square and three meters high. The air was recirculated back through the fan.
The crude controller was simply a large three phase contactor driven by a PID temperature controller. The contactor would cycle several times a minute and needless to say, fell apart on a regular basis!
As you can see, the new heater box and fan are much more professional and supplied by a local company Airtec Air Systems.
We then built a control panel using a 50 Amp three phase SSR driven by a West 6100+ PID temperature controller, taking advantage of its ramp facility to bring the oven up to temperature over half an hour.
The panel was fitted with a small Siemens Logo! PLC for the operator controls and also used its real time clock to automatically start the Oven during the night and switch it off after three hours.
The fan was controlled by a Schneider Altivar 12 Inverter so we could set the speed for the required air flow. As a by product, the slower fan speed reduced noise to acceptable levels
The panel was also fitted with an ABB SM500F penless data recorder tracing three zones within the Oven and this was also reported back to a management system via Ethernet for quality control and production logs.
We provided the frame for the heater and fan and installed the whole package over two days and the Oven has been in production ever since.