Im working in a shopping center, it is also hotel and office building, two towers exactly and someone is proposing a PLC control for the HVAC system, but Im thinking of a DDC control system. in this case what is the difference between PLC and DDC control?
I am a instrument technician. recently i attend interview and face one of question for DP transmitter ,the client asking about the calibration of DP transmitter ,am answer the calibration procedure, they will ask one more question. why open LP side in atmosphere? i did not answer that question. so please help me and explain the particular question. Dear firends waiting for your valuable replay