VLT
®
6000 HVAC Series
■ Example of application - Constant pressure
regulation in water supply system
The demand for water from waterworks varies
considerably during the course of a day. In the night,
practically no water is used, while in the morning
and in the evening the consumption is high. In order
to maintain a suitable pressure in the water supply
lines in relation to the current demand, the water
supply pumps are equipped with speed control.
The use of frequency converters enables the energy
consumed by the pumps to be kept at a minimum,
while optimizing the water supply to consumers.
A VLT 6000 HVAC with its integral PID controller
ensures simple and quick installation. For example,
an IP54 unit can be mounted close to the pump on
the wall and the existing line cables can be used as
mains supply to the frequency converter. A Pressure
transmitter (e.g. Danfoss MBS 33 0-10) bar can
be fitted a couples of metres from the joint outlet
point from the waterworks to obtain closed loop
regulation. Danfoss MBS 33 is a two-wire transmitter
(4-20 mA) that can be powered directly from a VLT
6000 HVAC. The required setpoint (e.g. 5 bar) can
be set locally in parameter 418 Setpoint 1.
Set the following parameters:
Par. 100 Configuration Closed loop [1]
Par. 205 Maximum reference 10 bar
Par. 302 Terminal 18 Digital inputs Start [1]
Par. 314 Terminal 60, analog input current Feedback signal [2]
Par. 315 Terminal 60, min. scaling 4 mA
Par. 316 Terminal 60, max. scaling 20 mA
Par. 403 Sleep mode timer 10 sec.
Par. 404 Sleep frequency 15 Hz
Par. 405 Wake-up frequency 20 Hz
Par. 406 Boost setpoint 125%
Par. 413 Minimum feedback 0
Par. 414 Maximum feedback 10 bar
Par. 415 Process units Bar [16]
Par. 418 Setpoint 1 5 bar
Par. 420 PID normal/inverse control Normal
Par. 423 PID proportional gain 0.5-1.0
Par. 424 PID integration time 3-10
Par. 427 PID low pass filter 0.5-1.5
MG.61.A5.02 - VLT is a registered Danfoss trademark
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