Points required for CHiller control

Thanks in advance. I need to programm the plc for chiller. i would like to know what are the soft points i need to create for PLC and SCADA in order the control the chiller and the relevant valves and sensors required.

Please help Thanks

Suggestion

I would suggest that you speak with the manufacturer of the chiller itself as well as the people that maintain the equipment.
I find that those two groups usually have the best insight into how a machine runs and what is best to monitor and control for smooth machine operation.
Michael

Well, it depends, doesn't it? I'm not an expert in chillers (I haven't put my hands on one for over 30 years) but they are not all the same. What kind of compressor do you have? What is the working fluid? Do you want equipment protection or just temperature control? How expensive is the equipment? (I spend more to protect a $100,000 machine than I do a $5,000 one.) How critical is the application? (I spend more to protect a blood bank than I do a cola cooler at the gas station.)

You need to do some homework, and then do some engineering. You can't reasonably expect someone to do your work for free. Even if they do, remember - you get what you pay for, or less!

What Tom said

There are numerous different chillers for numerous different systems. Is it a package chiller? Is the chiller water cooled or air cooled? Are you using water for the cooling media or Ethylene Glycol? Chilling multiple sources or one source? The list goes on and on.

You definitely have to get all of the data for this system and then design the protect and control of the chiller from there.

Regards,
Chris

heng_swee,

You would need:

(1) Start and Stop PLC Inputs, and 1 PLC Output for each Motor on the Chiller. A Chiller might have a Compressor Motor and a Fan Motor. It might also have other fans, depending on the Chiller cooling size.

(2) On/Off PLC Input, and 1 PLC Output for each control valve on the Chiller. A Chiller might have 1 Water Supply valve if it is water cooled. If it has a Cooling Tower, it might also have a Drain Valve. It could possibly have a valve to control the Cooling Fluid.

(3) Analog Input for Temperature Input setting from a temperature controller or other device.

(4) Analog Output to control Fan speed or valve position to regulate the temperature.

You know a chiller is cooling some liquid in temperature.
so you will need the incoming temeperature the outgoing temp and if flow is present, maybe even how much flow so you can calcualte the capacity.

on condenser same sensors.

on compressor the suction pressure, suction temp and discharge pres and temp.

i presume it is a schoolproject so if needed more input give more output.

safeties needed extra: low suction pressure (this is the pressure your chiller will freeze up.) high discharge pressure and high discharge temp.

control program: control expansion valve. in cascade mode so first look to superheat and second look at chiller temp.

Chiller

Thanks guys.This chiller plant system is a constant volume chiller water flow system with bypass control. There are three chillers, chilled water pump, condenser water pump and cooling tower.

This system is installed in a building.

I want to found out what are the soft points i need to create for effective control. E.g. Time out fault.

Thanks.