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• Digital Temperature Controller

Digital Temperature Controller

Digital Temperature Controller

INTRODUCTION

The on/off type single set point controller has digital display, set temperature preset and relay ON indication on its front side. Also on back side it has the input terminal or connectors for supply voltage i.e. (P, N, & Earth), relay contacts (Common, No, Nc) and sensor i.e. RTD or Thermocouple.

When we install the meter in the process by making proper connections first thing is set the desired temperature with the help of preset marked as ‘SET’ on front side by pressing the red knob indicated by ‘PRESS TO SET’ say you have set 100°C. Say process temperature is at room temperature, relay is in ON condition at this stage.

As process temperature increases and as soon as it crosses the set temperature value relay will turn OFF. When the process temperature comes below set temperature, relay will turn ON. Thus this controller maintains the set temperature.

TIME PROPORTIONAL CONTROL

In Time Proportional Control, there is a preset proportional band, normally set to 5% to 10% of set point. Within this band, the relay is continuously switched ON & Off.

The duration of off time can be adjusted by the preset given on the front plate indicated by ‘RESET’. If preset is turned clockwise, the ‘OFF’ time increases and when it is turned anti-clockwise, ‘OFF’ time decreases.

This Time Proportioning action can be turned to on/off type action simply by turning the ‘RESET’ preset fully anti-clockwise.

TWO SET POINT CONTROLLER

This controller has two different set points two different relays. It has a display ‘SET1’ and ‘SET2’ preset for setting the desired temperature band. There are two ‘PRESS TO SET’ knobs for setting respective ‘SET’ preset. Also two relay on indication LED’s. the back side of this controller contains the terminals for supply Phase, neutral, Earth also the contact points Pole1,No1,Nc1 & Pole2, No2,Nc2 for two different relays.

After installation set the desired temperature band with the help of preset SET1& SET2 by pressing the appropriate ‘PRESS TO SET’ switch. Assume SET1 is 10°C & SET2 is 20°C. so we have selected a 10°C band.

This controller has two different set points and two relay outputs. It senses the temperature at any one point, but you can set two different temperatures by two set points. This can be used set a band of temperature.

Two set point controller with single relay can be used for chiller application for controlling compressor ON/OFF to maintain temperature.

This controller can also be operated as a two-channel controller. It has one controller and one indicator.

Digital Temperature Indicator

WORKING

Digital temperature indicator is used for only indication purpose of the process. The thermocouple input is amplified by a low drift amplifier. Then signal is fed to an analog to digital converter. The process temperature is displayed on 7- segment display. As the process temperature increases that increases temperature is displayed by the meter.

The indicator has a display on is front and supply and sensor terminals on back side.

The indicator also comes in a version of 2 to 12 points or as demanded by user.

In six-point indicator there comes selector switch on front to select the sensor of associated process. On backside of the meter there are six different input terminals. So on one temperature indicator meter we can see temperature of six different places. Same is for 12 point.