Frequency Inverter DF51... - Moeller.com.tr

Setting parameters04/07 AWB8230-1541GBFeedback value check signal (FBV)The FBV (Feedback Value Check) signal is issued when the actual(process) value (PV) drops below the lower limit value (PNU C053)in RUN mode. It remains active until:• the actual value exceeds the upper limit value (PNU C052).• the frequency inverter changes from RUN mode to STOP mode(deceleration with the set ramp time).FWDPVFBV1M1Start2M20... 10 V/ 4... 20 mA%bFigure 149: Block diagram, ventilation with “two-stage control”1: <strong>Frequency</strong> inverter with PID control for fan motor M12: Motor starter (frequency inverter, soft starter, contactor) for fanmotor M2FWD: Start signal, drive 1 (clockwise rotating field)FBV: Feedback value check signal from drive 1 for actuating drive 2PV: Process variable (airflow m 3 /h) as normalized actual value signalStart: Start signal, drive 2C052C053atFWDFBVThe control sequence for the example cited here is illustrated bythe graph in fig. 148. The process variable and the limit values areshown as a percentage here. The output frequency (Hz) is alsoshown.Figure 148: PID control, feedback value check signal (FBV)a Output frequency (Hz)b Actual value (process variable – PV)FWD: Start signal, clockwise rotating fieldFBV: Feedback value check signal, limit values PNU C052, C053exceededh The upper and lower actual value limits (PNU C052,C053) are “process signals”: they cannot be used formonitoring the feedback value check signal. FBV is not afault signal.With PNU C021 or C022 you can set value 07 (FBV) for a digitaloutput (11, 12) or, with PNU C026, for signalling relay K1 (K11-K12).• Start fan motor M1 with FWD signal. The feedback value (PV)lies below the limit value specified with. The FBV output (11,12, K1) therefore switches to also start fan motor M2.• The actual value rises and reaches the upper limit (PNU C052).The FBV output is automatically switched off (= fan M2 Off).Fan M1 remains in operation and works in linear control mode.In a correctly set up system, this is the normal operating range.• yIf the actual value drops below the limit value (PNU C053), theFBV output is switched and fan M2 is activated again to supportfan M1.• When the FWD signal is removed from frequency inverter 1, theinverter goes from RUN to STOP mode and decelerates the driveover the set ramp time.• When frequency inverter 1 is stopped, the FBV output isautomatically de-energized so that fan M2 also stops.With the feedback value check signal (FBV), the DF51’s PIDcontroller can provide a direct “two-stage control”, as <strong>com</strong>monlyused for ventilation and air conditioning applications.Example: ventilation system with two fans (frequency inverter).Under normal operating conditions, the maximum output powerof fan 1 (M1) is sufficient to maintain the actual value (PV) at thereference value. When fan 1 is fully utilized and additional airflowis required, a second fan (M2) with constant power is a simplesolution.134