In this process, two chemical streams are mixed together in a reactor vessel. The ensuing chemical reaction is exothermic (heat-producing) and must be cooled by a water cooling system to prevent overheating of the vessel and piping. A temperature transmitter (TT) senses the reaction product temperature and sends a 4-20 mA signal to a temperature indicating controller (TIC). The controller then sends a 4-20 mA control signal to the temperature valve (TV) to throttle cooling water flow:
Suppose an instrument technician adds a temperature-indicating chart recorder (TIR) to the temperature transmitter circuit, necessitating the addition of a 250 ohm resistor to the 4-20 mA circuit to provide a 1-5 volt voltage signal which the recorder can read. Now the 4-20 mA temperature circuit has more resistance in it than it did before.
Describe in detail the effect this circuit modification will have on the performance of the cooling system.
This circuit modification will have absolutely no effect on the performance of the system, as long as the loop-powered transmitter receives its minimum terminal voltage for proper operation.