KROHNE VFM 5090 EN User Manual

Page 48

Frequency output value is directly proportional to the flow rate, power and net power. Programming of frequency
output value is provided by 1.4 functions.

Fct. 1.4.1 FUNCTION F frequency output

Choose YES -to make frequency output active as per functions Fct. 1.4.2 to Fct. 1.4.3. NO makes frequency
output inactive (0 Hz). When frequency output function is not required choose the option NO.

Fct. 1.4.2 RANGE F frequency output range value

Frequency output is 0 Hz for 0 flow rate and the value programmed in RANGE F for qmax flow rate. [qmax is
the maximum flow programmed in Fct. 1.1.2 MAX. FLOW] RANGE F can be programmed in pulse/time units
or in the form of pulse/unit flow units. See example below :

Example of pulses/unit flow

Full scale setting, qmax

: 1000 Litre/sec (set via Fct. 1.1.2)

RANGE F

: 1 PULSE/Litre (set via Fct. 1.4.2)

at 1000 litres per second

: 1000 pulses per second = 1 pulse per litre.

Changeover of

Full scale setting, qmax

: 2000 Litre/sec (set via Fct. 1.1.2)

RANGE F

: unchanged, 1 PULS/Litre (set via Fct. 1.4.2)

at 2000 litres per second

: 2000 pulses per second = 1 pulse per litre as before.

Example of pulses/time
Full scale setting, qmax

1000 Litre/sec (set via Fct.1.1.2)

RANGE F

: 1000 PULSE/sec (set via Fct.1.4.2)

Pulse value is then

: 1 pulse per litre

Changeover of
Full scale setting, qmax

2000 Litre/sec (ser via Fct.1.1.2)

RANGE F

: unchanged 1000 PULSE/sec (set via Fct. 1.4.2)

Pulse value is now

: 1 pulse per 2 litres

For limits on programming of RANGE F refer to Sect. 6.

Frequency output automatically works in the pulse mode when the following conditions are satisfied

1) fmax evaluates to

£ 0.5 Hz

2) Internal electronic totalizer is ON.
3) fmax is programmed in pulses/unit flow units.
In pulse mode of operation, the pulse output is generated by tracking the totalized flow and thus provides true
reflection of internal totalizer value.

Fct. 1.4.3 PULS. WIDTH pulse width

Enables to limit the active duration of frequency output, to reduce the overheating of external electromechanical
totalizer coil. Available only when RANGE F evaluates to

£ 10 Hz. Possible widths to select are -

30 / 50 / 100 / 200 / 500 mSecs. For details refer to Sect. 6.

Fct. 1.4.4 VARIABLE F frequency output selection function.