CG Drives & Automation,01-5326-01r5 Functional Description 145
PID Activation Margin [387]
The PID activation (wake-up) margin is related to the
process reference and sets the limit when the AC drive
should wake-up/start again.
Communication information
Example 1 PID control = normal (flow or
pressure control)
[321] = F (AnIn)
[322] = Bar
[310] = 20 Bar
[342] = 2 s (inactive since [386] is activated and have higher
priority)
[381]= On
[386] = 10 s
[387] = 1 Bar
The AC drive will stop/sleep when the speed (PID output) is
below or equal to Min Speed for 10 seconds. The AC drive
will activate/wake up when the “Process value” goes below
the PID Activation Margin which is related to the process
reference, i.e. goes below (20-1) Bar. See Fig. 112.
Fig. 112 PID Stop/sleep with normal PID
Example 2 PID control = inverted (tank
level control)
[321] = F (AnIn)
[322] = m
[310] = 7 m
[342] = 2 s (inactive since [386] is activated and have higher
priority)
[381]= Inverted
[386] = 30 s
[387] = 1 m
The AC drive will stop/sleep when the speed (PID output) is
below or equal to Min Speed for 30 seconds. The AC drive
will activate/wake up when the “Process value” goes above
the PID Activation Margin which is related to the process
reference, i.e. goes above (7+1) m. See Fig. 113.
Fig. 113 PID Stop/sleep with inverted PID
PID Steady State Test [388]
In application situations where the feedback can become
independent of the motor speed, this PID Steady Test
function can be used to overrule the PID operation and
force the AC drive to go in sleep mode i.e. the AC drive
automatically reduces the output speed while at the same
time ensures the process value.
Example: pressure controlled pump systems with low/no
flow operation and where the process pressure has become
independent of the pump speed, e.g. due to slowly closed
valves. By going into Sleep mode, heating of the pump and
motor will be avoided and no energy is spilled.
PID Steady state test delay.
Communication information
387 PID Act Marg
Default: 0
Range: 0 –10000 in Process unit
Modbus Instance no/DeviceNet no: 43372
Profibus slot/index 170/21
EtherCAT and CANopen index (hex) 4d2c
Profinet IO index 19756
Fieldbus format
Long, 1= 1 rpm, 1
%, 1°C or
0.001 if Process
Value/Process Ref
using a [322] unit
Modbus format EInt
NOTE: The margin is always a positive value.
[711] Process Value
[387]
[712] Speed
[341] Min Speed
[386]
Stop/Sleep
[310] Process Ref
Activate/Wake up
NOTE: It is important that the system has reached a
stable situation before the Steady State Test is
initiated.
388 PID Stdy Tst
Default: Off
Range: Off, 0.01–3600 s
Modbus Instance no/DeviceNet no: 43373
Profibus slot/index 170/22
EtherCAT and CANopen index (hex) 4d2d
Profinet IO index 19757
Fieldbus format Long, 1=0.01 s
Modbus format EInt
[711] Process Value
[387]
[712] Speed
[341] Min Speed
[386]
Stop/Sleep
[310] Process Ref
Activate/Wake up
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