NOTE
If
the frequency converter is equipped with a constant
speed bypass with an automatic bypass function that starts
the bypass if the frequency converter experiences a
persistent alarm condition, be sure to disable the bypass’s
automatic bypass function, if [2] Trip is selected as the
Broken Belt Function.
22-61 Broken Belt Torque
Range: Function:
10 %* [0 - 100 %] Sets the broken belt torque as a percentage
of
the rated motor torque.
22-62 Broken Belt Delay
Range: Function:
10 s [0 - 600 s] Sets the time for which the Broken Belt
conditions
must be active before carrying out
the action selected in 22-60 Broken Belt
Function.
3.17.6 22-7* Short Cycle Protection
When controlling refrigeration compressors, often there
will
be a need for limiting the numbers of starts. One way
to do this is to ensure a minimum run time (time between
a start and a stop) and a minimum interval between starts.
This means that any normal stop command can be
overridden by the Minimum Run Time function
(22-77 Minimum Run Time) and any normal start command
(Start/Jog/Freeze) can be overridden by the Interval
Between Starts function (22-76 Interval between Starts).
None of the two functions are active if Hand On or Off
modes have been activated via the LCP. If selecting Hand
On or Off, the two timers will be reset to 0, and not start
counting until Auto is pressed and an active start
command applied.
NOTE
A
Coast command or missing Run Permissive signal will
override both Minimum Run Time and Interval Between
Starts functions.
22-75 Short Cycle Protection
Option: Function:
[0] Disabled
Timer set in22-76
Interval between Starts is disabled.
[1] Enabled
Timer set in 22-76
Interval between Starts is
enabled.
22-76 Interval Between Starts
Range: Function:
300 s* [0 - 3600 s] Sets the time desired as minimum time
between
two starts. Any normal start
command (Start/Jog/Freeze) will be
disregarded until the timer has expired.
22-77 Minimum Run Time
Range: Function:
0 s* [ 0
- par.
22-76
s]
Sets the time desired as minimum run time
after a normal start command (Start/Jog/
Freeze). Any normal stop command will be
disregarded until the set time has expired. The
timer will start counting following a normal
start command (Start/Jog/Freeze).
The timer will be overridden by a Coast
(Inverse) or an External Interlock command.
NOTE
Does
not work in cascade mode.
22-78 Minimum Run Time Override
Option: Function:
[0] Disabled
[1] Enabled
22-79 Minimum Run Time Override Value
Range: Function:
0 ProcessCtrlUnit* [-999999.999 - 999999.999
ProcessCtrlUnit]
3.17.7 22-8* Flow Compensation
It is sometimes the case that is not possible for a pressure
transducer to be placed at a remote point in the system
and it can only be located close to the fan/pump outlet.
Flow compensation operates by adjusting the set-point
according to the output frequency, which is almost propor-
tional to flow, thus compensating for higher losses at
higher flow rates.
H
DESIGN
(Required pressure) is the setpoint for closed loop
(PI) operation of the frequency converter and is set as for
closed loop operation without flow compensation.
It is recommended to use slip compensation and RPM as
unit.
Parameter Description
VLT
®
Refrigeration Drive Programming Guide
136 MG16H102 - VLT
®
is a registered Danfoss trademark
33
To Next Page
Loading...
Need help?
General