Flow Confirmation - Danfoss VLT AQUA Drive FC 202 Design Manual

Application Examples

4.2.5 29-5* Flow Confirmation

The flow confirmation feature is designed for applications
where there is a need for the motor/pump to run while
waiting for an external event. The flow confirmation
monitor expects to get a digital input from a sensor on a
gate valve, flow switch, or a similar external device
indicating that the device is in the open position and flow
is possible. In 29-50 Validation Time, a user defines how
®
long the VLT AQUA Drive FC 202 waits for the digital
input signal from the external device to confirm the flow.
After the flow is confirmed, the adjustable frequency drive
checks the signal again after the flow verification time and
then runs normally. The LCP status reads "Verifying flow"
while the flow monitor is active.
The adjustable frequency drive trips with the alarm Flow
Not Confirmed, if the expected digital input signal becomes
inactive before either the flow validation time or the flow
verification time expires.
N
MAX
1
N
MIN
0
2
1
0
3
1
4 0
1
0
t0
1 Speed curve
2 Start command (for example, terminal 18)
3 Digital signal from an external device that confirms that
the flow is possible.
4 Flow verification
t Start command issued (for example, terminal 18 is set
0
active)
t Digital signal from an external device becomes active
1
before 29-50 Validation Time expires.
t When 29-51 Verification Time passes, the adjustable
2
frequency drive checks the signal from the external
device again and then runs normally.
Figure 4.3 Flow Confirmation
MG20N622
Design Guide
T
T
T
T
<t1 t2
Danfoss A/S © 09/2014 All rights reserved.
Parameter and Description
Name
29-50 Validatio The digital input
n Time must be active
during the
validation time.
29-51 Verifi- Flow will be
cation Time confirmed if, at the
end of the verifi-
cation time, the
digital input is still
active.
Table 4.2 Flow Confirmation Parameters
NOTICE!
The parameters are only visible on the LCP when a
digital input is configured as flow confirmation.
4.2.6 Advanced Minimum Speed
Monitoring for Submersible Pumps
Some pumps are very sensitive to operating at low speed.
Typical reasons for this are insufficient cooling or
lubrication at low speed.
Under overload conditions, the adjustable frequency drive
protects itself using its integral protection features, which
include lowering the speed. For example, the current limit
controller can lower the speed. This means that, in some
cases, the speed may go lower than the speed specified in
4-11 Motor Speed Low Limit [RPM] and 4-12 Motor Speed
Low Limit [Hz].
The advanced minimum-speed monitoring feature trips the
adjustable frequency drive if the speed drops below a
certain value. If the pump motor of the pump does not
reach the speed specified in 1-86 Trip Speed Low [RPM]
within the time specified in 1-79 Pump Start Max Time to
Trip (ramping up takes too long), the adjustable frequency
drive trips. Timers for 1-71 Start Delay and 1-79 Pump Start
Max Time to Trip start at the same time when the start
command is issued. For instance, this means that if the
value in 1-71 Start Delay is more than or equal to the value
in 1-79 Pump Start Max Time to Trip, the adjustable
frequency drive never starts.
Settings Unit
0.1–999.0 s
(*size dependent)
0.1–255.0 s
(*15)
103
4 4