Flow Confirmation Overview; Advanced Minimum Speed Monitoring Overview - Danfoss VLT AQUA Drive FC 202 Design Manual

Product Features

5.8 Flow Confirmation Overview

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 receive 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 parameter 29-50 Validation Time, define for
®
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 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.
If the expected digital input signal becomes inactive before
either the flow validation time or the flow verification time
expires, the drive trips with the alarm alarm 92, No flow.
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 parameter 29-50 Validation Time expires.
t When parameter 29-51 Verification Time passes, the drive
2
checks the signal from the external device again and
then runs normally.
Illustration 5.14 Flow Confirmation
MG22B102
Design Guide
T
T
T
T
<t1 t2
Danfoss A/S © 05/2017 All rights reserved.
Parameter and Description
name
Parameter 29-5 The digital input
0 Validation must be active
Time during the
validation time.
Parameter 29-5 Flow will be
1 Verification confirmed if, at the
Time end of the verifi-
cation time, the
digital input is still
active.
Table 5.2 Flow Confirmation Parameters
NOTICE
The parameters are only visible on the LCP when a
digital input is configured as flow confirmation.
5.9 Advanced Minimum Speed Monitoring
Overview
Some pumps are sensitive to operating at low speed.
Insufficient cooling or lubrication at low speed are typical
reasons.
Under overload conditions, the drive protects itself using
its integral protection features, which include lowering the
speed. For example, the current limit controller can lower
the speed. Sometimes, the speed can go lower than the
speed specified in parameter 4-11 Motor Speed Low Limit
[RPM] and parameter 4-12 Motor Speed Low Limit [Hz].
If the speed drops below a certain value, the advanced
minimum-speed monitoring feature trips the drive. If the
pump motor does not reach the speed specified in
parameter 1-86 Trip Speed Low [RPM] within the time
specified in parameter 1-79 Pump Start Max Time to Trip
(ramping up takes too long), the drive trips. Timers for
parameter 1-71 Start Delay and parameter 1-79 Pump Start
Max Time to Trip start at the same time when the start
command is issued. For example, if the value in
parameter 1-71 Start Delay is more than or equal to the
value in parameter 1-79 Pump Start Max Time to Trip, the
drive never starts.
Settings Unit
0.1–999.0 s
(*size dependent)
0.1–255.0 s
(*15)
25
5 5