TECO F33 Series, Инструкция по эксплуатации, Страница: 106 / 192

Functional Description 103
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 VSD to go in sleep mode i.e. the
VSD 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
PID Steady State Margin [389]
PID steady state margin defines a margin band around
the reference that defines “steady state operation”.
During the steady state test the PID operation is over-
ruled and the VSD is decreasing the speed as long as
the PID error is within the steady state margin. If the
PID error goes outside the steady state margin the test
failed and normal PID operation continues, see exam-
ple.
Communication information
Example: The PID Steady Test starts when the process
value [711] is within the margin and Steady State Test
Wait Delay has expired. The PID output will decrease
speed with a step value which corresponds to the mar-
gin as long as the Process value [711] stays within
steady state margin. When Min Speed [341] is reached
the steady state test was successful and stop/sleep is
commanded if PID sleep function [386] and [387] is
activated. If the Process value [711] goes outside the
set steady state margins then the test failed and nor-
mal PID operation will continue, see Fig. 90.
Fig. 90 Steady state test
11.3.9 Pump/Fan Control [390]
The Pump Control functions are in menu [390]. The
function is used to control a number of drives (pumps,
fans, etc.) of which one is always driven by the VSD.
NOTE: It is important that the system has reached a
stable situation before the Steady State Test is initiated.
Default: Off
Range: Off, 0.01–3600 s
Modbus Instance no/DeviceNet no: 43373
Profibus slot/index 170/22
Fieldbus format Long, 1=0.01 s
Modbus format EInt
388 PID Stdy Tst
Stp Off
A
Default: 0
Range: 0–10000 in process unit
Modbus Instance no/DeviceNet no: 43374
Profibus slot/index 170/23
Fieldbus format Long, 1=0.01 s
Modbus format EInt
389 PID Stdy Mar
Stp 0
A
time
[711] Process Value
[310] Process Ref
[387]
[712] Speed
[388]
Stop/Sleep
[389]
[389]
[341] Min Speed
[386] PID<Min Spd
Normal PID
Stop steady Start steady
Steady state
Normal PID
test
state test
state test