GE AF-600 FP Series, Design Manual

Page: 30 / 176

2.8.3 Local (Hand) and Remote (Auto) Control
The frequency converter can be operated manually via keypad or remotely via analog/digital inputs or serial bus.
If allowed in par. K-40
[Hand] Button on Keypad , par. K-41 [Off] Button on Keypad , par. K-42 [Auto] Button on Keypad , and par. K-43 [Reset] Button on Keypad , it is
possible to start and stop the frequency converter bykeypad using the [Hand] and [Off] keys. Alarms can be reset via the [RESET] key. After pressing the [Hand]
key, the frequency converter goes into Hand Mode and follows (as default) the Local reference set by using the keypad arrow keys up [
▲
] and down [
▼
].
After pressing the [Auto] key, the frequency converter goes into Auto mode
and follows (as default) the Remote reference. In this mode, it is possible to
control the frequency converter via the digital inputs and various serial in-
terfaces (RS-485, USB, or an optional network). See more about starting,
stopping, changing ramps and parameter set-ups etc. par. group O-5# (serial
communication).
Hand Off
Auto
keypad Keys Reference Site
par. F-02
Operation Method
Active Reference
Hand Linked to Hand / Auto Local
Hand -> Off Linked to Hand / Auto Local
Auto Linked to Hand / Auto Remote
Auto -> Off Linked to Hand / Auto Remote
All keys Local Local
All keys Remote Remote
The table shows under which conditions either the Local Reference or the Remote Reference is active. One of them is always active, but both can not be active
at the same time.
Local reference will force the configuration mode to open loop, independent on the setting of par. H-40 Configuration Mode .
NB!
Local Reference will be restored at power-down.
2.8.4 Control Structure Closed Loop
The closed loop controller allows the drive to become an integral part of the controlled system. The drive receives a feedback signal from a sensor in the system.
It then compares this feedback to a set-point reference value and determines the error, if any, between these two signals. It then adjusts the speed of the motor
to correct this error.
For example, consider a pump application where the speed of a pump is to be controlled so that the static pressure in a pipe is constant. The desired static pressure
value is supplied to the drive as the set-point reference. A static pressure sensor measures the actual static pressure in the pipe and supplies this to the drive as
a feedback signal. If the feedback signal is greater than the set-point reference, the drive will slow down to reduce the pressure. In a similar way, if the pipe
pressure is lower than the set-point reference, the drive will automatically speed up to increase the pressure provided by the pump.
AF-600 FP Design Guide
29
2