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TSN79
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I need some help with this ladder diagram that is for a cooling system. Here is the assignment:
The system has two rooms that need to be cooled. There is one evaporator in each room with one fan. The evaporators should have an electric anti-ice system (heat rods) that is to be controlled by a timer and a thermostat. The fans should have a delayed start after the anti-ice process finishes.
The compressor has a capacity-regulator that is regulated with a low pressurestat (stops two cylinders when pressure falls). The system is to be controlled by the "pump down" principle with its own LP-pressurestat. The condenser has two fans. One fan should always run when the compressor runs, and the second one should engage via its own HP-pressurestat.
The control board should have the following lights:
- Running compressor
- Compressor stopped by either HP-pressurestat or engine protection.
- Anti-ice in any of the two rooms, two lights.
There should be these switches:
- Start compressor and condenser
- Start switch for both rooms
Now, the attachment shows a diagram that is supposed to be correct, but I need serious explanation to understand the concept of these diagrams. I have a list of questions I have:
- The different squares labeled K1, K2 and so on, these are simply supposed to represent the compressor, the fans, and so on, right?
- What is the difference between the type of switches at the red circles A, B and C?
- What is the purpose of the magnet valve?
The system has two rooms that need to be cooled. There is one evaporator in each room with one fan. The evaporators should have an electric anti-ice system (heat rods) that is to be controlled by a timer and a thermostat. The fans should have a delayed start after the anti-ice process finishes.
The compressor has a capacity-regulator that is regulated with a low pressurestat (stops two cylinders when pressure falls). The system is to be controlled by the "pump down" principle with its own LP-pressurestat. The condenser has two fans. One fan should always run when the compressor runs, and the second one should engage via its own HP-pressurestat.
The control board should have the following lights:
- Running compressor
- Compressor stopped by either HP-pressurestat or engine protection.
- Anti-ice in any of the two rooms, two lights.
There should be these switches:
- Start compressor and condenser
- Start switch for both rooms
Now, the attachment shows a diagram that is supposed to be correct, but I need serious explanation to understand the concept of these diagrams. I have a list of questions I have:
- The different squares labeled K1, K2 and so on, these are simply supposed to represent the compressor, the fans, and so on, right?
- What is the difference between the type of switches at the red circles A, B and C?
- What is the purpose of the magnet valve?