FC101 Design Guide

ManualsBrandsSystemair ManualsElectrical accessories VentilationFC101-37kW/73A-IP20, 50/20m - frequency inverter 400V, no display, controller

3.2.3 Local (Hand On) and Remote (Auto

On) Control

The frequency converter can be operated manually via the

local control panel (LCP) or remotely via analog/digital

inputs or serial bus. If allowed in parameter 0-40 [Hand on]

Key on LCP, parameter 0-44 [O/Reset] Key on LCP, and

parameter 0-42 [Auto on] Key on LCP, it is possible to start

and stop the frequency converter via LCP by pressing

[Hand On] and [O/Reset]. Alarms can be reset via the

[O/Reset] key.

Hand

Oﬀ

Reset

Auto

130BB893.10

Figure 3.18 LCP Keys

Local reference forces the conguration mode to open-

loop, independent on the setting of

parameter 1-00

Conguration Mode.

Local reference is restored at power-down.

3.2.4 Control Structure Closed Loop

The internal controller allows the frequency converter to

become a part of the controlled system. The frequency

converter receives a feedback signal from a sensor in the

system. It then compares this feedback to a setpoint

reference value and determines the error, if any, between

these 2 signals. It then adjusts the speed of the motor to

correct this error.

For example, consider a pump application where the speed

of a pump is to be controlled to ensure a constant static

pressure in a pipe. The static pressure value is supplied to

the frequency converter as the setpoint reference. A static

pressure sensor measures the actual static pressure in the

pipe and supplies this data to the frequency converter as a

feedback signal. If the feedback signal is greater than the

setpoint reference, the frequency converter slows the

pump down to reduce the pressure. In a similar way, if the

pipe pressure is lower than the setpoint reference, the

frequency converter automatically speeds the pump up to

increase the pressure provided by the pump.

7-30 PI

Normal/Inverse

Control

Reference

Feedback

Scale to

speed

P 4-10

Motor speed

direction

To motor

control

130BB894.11

100%

-100%

100%

*[-1]

Figure 3.19 Control Structure Closed-loop

While the default values for the closed-loop controller of

the frequency converter often provide satisfactory

performance, the control of the system can often be

optimized by adjusting parameters.

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HVAC Basic Drive FC 101