We needed to automatically switch on the 5 heaters with time delay between each other. We used PoRelay8 as time delay switch that automatically switched on the heaters one after another.
Why do we need time delay for heaters?
We have reflow oven for soldering PCBs. When we switch it on, there are 5 heaters that turn on simultaneously and maintain temperature in 5 zones. The problem that we have is that they consume a lot of power when heating up together but then the power drops significantly when it only needs to maintain the temperature.
The high power surge is problematic with our system of billing the electricity. The bill is much higher if there are big power surges / spikes. So it is the best to maintain as smooth power consumption as possible. That is why we want to switch on heaters individually with fixed time delay between them. That way it takes more time for the oven to heat up (15min instead of 3) but the power consumption is about 5 times smaller.
How to add delay with PoRelay8?
Our 8 channel relay board allows you to program custom logic with our graphical programming software PoBlocks. It can then act as PLC and can coordinate switching outputs. Furthermore, we added 4 digital inputs for additional capability of conditioning output triggering with inputs. That way, the possibilities are endless and PoRelay8 can act as standalone controller for simple and more complicated tasks.
We made a simple schematic with PoBlocks with 5 outputs and 1 input. That way the sequence of turning on the outputs is triggered with one button. The button is already integrated on the oven, we just had to wire the cable to the input of the PoRelay8. Then all 5 heaters are turned on one after another. The clock is there to count time with 1s period.
Wiring of time delay switch
The wiring was straight forward. Previously, heaters were switched on manually. All we had to do was to cut away the manual switches and wire the conductors through relay outputs on the PoRelay8. We chose NO (normally open) connection for obvious reasons.
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