Temperature controllers

Digital temperature controllers

Digital indicators

Modular electronic thermostats

INTRODUCTION
Temperature controllers allow, through temperature desired value's statement (set-point), to check and to keep the temperature prearranged value of the warming element steady, comparing the value pointed out by the sensor with the one adopted by the user.

Elco temperature controllers can be analogue or microprocessor-based type. Particularly microprocessor-based tools, thanks to easiness and flexibility of parameters' planning, offer a wide possibility of temperature's adjustment. A lot of these instruments have, besides PID control, also the AUTOTUNNING function which allow to calculate regulation parameters automatically.

Most of microprocessor based tools can use, as input signals for temperature's control, besides traditional thermocouple or thermoresistance probes, also analogue signals in current or in voltage and through HEATER BREAK function can point-out incidental failures or interruptions of the warming element.

Flexibility to various applications of ELCO temperature controllers is easily verifiable also from the number and typology of outputs, both principal and auxiliary that they have. The main output is used for keeping the layed out temperature and it's coupled with secondary outputs used to signal alarms, interruption of the warming element, heating or cooling phases, etc. The type of intervention and modalities of output's switchover are fixed at the moment of temperature controller's programming.

TYPES OF REGULATION
Types of regulation that temperature controllers can realized are:

ON - OFF regulation: simple and fairly slow temperature adjustment, very sensitive to power-supply or load variations. Output is ON state for temperature lower than prearranged value (set-point), whereas it's OFF state for higher temperature.

"P" regulation (proportional): this type of adjustment is adopted when we want remove temperature's hysteresis on the warming element typical of ON - OFF regulation. In this sense user defines two temperatures (proportional band) which include set-point, where the temperature's regulation is carried out with continuity in conformity with a time called proportional cycle (duty cycle) during which output's ON and OFF times change. This type of adjustment allow a good temperature's steadiness but it's characterized from a temperature's difference as regards set point's value (offset).

"PD" regulation (proportional-derivative): Proportional - derivative regulation with the addition of "P" regulation allow to make a quick return to set-point value in case of a rapid variation of temperature caused by strong exterior troubles.

"PID" regulation (proportional-integrated-derivative): PID regulation allow temperature's control using at the same time PD action and the integral "I" action with whom we can remove the temperature's offset typical of the proportional regulation automatically.

auto-tuning: auto-tuning function allow to temperature controller, throught a selflearning cycle, to calculate automatically all optimal values of PID action's parameters basing on characteristics of element to warm.

TEMPERATURE PROBES
As support at its own temperature controllers, the company ELCO can supply a complete range of temperature probes.

a. Thermocouple (J,K,S,R,T type, etc.)
temperature range: til 1800 °C - class of accuracy: 1 or 2 - reference regulations: IEC 584-2

b. Thermoresistance ( Pt100 or Ni 100)
temperature range: from -200 °C to +850 °C - class of accuracy: A or B - reference regulations: IEC 571

c. Thermistor (PTC KTY 81 types)
temperature range: from -50 °C to +150 °C

All probes are moreover available in different shapings, formats, prods and types of cables also on customer's specification.

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