Diagram
to
control
the
heating
of
liquid
in
the
tank
Problem Solution
To detect high and low level of liquid in the tank, two level switches are used which gives output in digital
terms, that is when corresponding levels are detected, it gives output high otherwise remain low.
To control level of this system, Single Acting Piston valve can be used which has two states, either fully
open or fully close and to heat the liquid, heater is used.
Low Level Switch is mounted at the bottom of the tank and Level High switch is mounted at the side-upper
most position.
Heater is installed inside the tank and temperature sensor such as RTD or Thermocouple may be used to
detect the temperature of liquid in the tank.
PLC Program
Here is PLC program for Heating Liquid in the Tank by Heater, along with program explanation and run
time test cases.
List
of Inputs and Outputs
I:1/0
= Level High Switch
(Input)
I:1/1
=
Level Low Switch
(Input)
O:2/0
= Inlet Valve
(Output)
O:2/1
= Outlet Valve
(Output)
O:2/2
= Heater
(Output)
I:1/14 = Start
(Input)
I:1/15 = Stop
(Input)
N7:1
=
Temperature Data
(Register)
