Trane TRG-TRC013-EN manual Fan-SpeedControl

g

Fan-Speed Control

variable-speed drive

g MD

k

cwt	2 –—s
rp°prx
prr—–°“x2
2 p
s

Fan-Speed Control

static pressure

sensor set point

fan speed curves
		%
VAV system	&	$
modulation
curve

design system resistance curve

airflow g ME

cwt

Again, as the system resistance curve shifts upward and the fan begins to “ride up” the constant-speed performance curve, toward f, from its design operating point e, it delivers a lower airflow at a higher static pressure. The system static- pressure controller senses this higher static pressure and sends a signal to the fan-speed controller, instructing it to slow down the fan motor. This causes the performance curve for the fan to shift downward until the balance point g falls

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