What is needed for electrical heating? In fact, this question is asked too seldom. Of course, there are people who know everything and therefore ask no questions. (And this page is just intended for those people who can read this without coming out themselves.) For those who want to ask questions the heatsystems team is readily available.
And you will find a lot of other details on (not only) electrical heat in heatpedia, the heatsystems encyclopedia.
The heater
Of course, a heater is needed for heating. The heater must have been designed according to the general conditions (fluids, temperatures, environment etc.). For example, cooking rice pudding with an immersion heater will provide less pleasure since the surface load is much too high for this application.
heatsystems will readily give you advice on the design.
The fluid
Heat is transferred there. Depending on the fluid and the environment, special aspects have to be considered, e.g. that a maximum temperature must not be exceeded or that an explosion-proof design is required.
Closed-loop control
Only the fewest heating elements (i.e. the self-limiting PTC heating elements) can do without closed-loop control. All other elements must be controlled and limited. This requires switching elements (e.g. contactors) which can only be installed directly to the heater in case of low powers (below approx. 10 kW). Higher powers require a {switchgear cabinet or a switchbox.}
Temperature measurement
Close-loop control requires that the temperature of the fluid be detected, normally by a sensor in the fluid. For this resistance sensors (PT100, PT1000, NTC), thermocouples or electromechanical sensors (bimetallic, capillary thermostats) can be used. The controller needs the signals from these sensors (analog or digital) to determine when to activate the heater.
Temperature limiters are required for a lot of applications. Our advice: Always consider a temperature limiter with a safety circuit. The extra price for this limiter is always lower than the damage possibly caused by a failing controller.
Safety circuit
The safety circuit deactivates heating power and works independently of the normal switching of the heater by the controller. If the controller fails or the contactor of the control system is sticking (yes, this occurs more frequently than imagined), the contactor of the safety circuit must still be capable of releasing. {Switchgear cabinets and switchboxes} from heatsystems always have a safety circuit.
And of course, we can also evaluate the circuits according to SIL.