which is pulse width modulated by the mpu. In the plastics industry, more over extrusion processes, the heater bands are usually 1 to 2kw rated, for this, a 16amp 250Vac relay contact capability is used. The problem is that after a couple of months use, the relay contacts give and a replacement relay is then required. This easily fixed if the relay sits plugged into an appropriate pcb relay base. Alternatively if the relay is soldered directly on the pcb then exchanging the relay is both messy and time consuming.