Bumpless Transfer - Brainchild BTC-2500 User Manual

3 18 Bumpless Transfer

3 18 Bumpless Transfer
The bumpless transfer function is available for output 1 and output 2 ( provided The bumpless transfer function is available for output 1 and output 2 ( provided
that OUT2 is configured as COOL ). that OUT2 is configured as COOL ).
Bumpless Transfer Bumpless Transfer is enabled by selecting BPLS for O1FT and/or O2FT and is enabled by selecting BPLS for O1FT and/or O2FT and
activated as one of the following cases occurs : activated as one of the following cases occurs :
1. Power starts ( within 2.5 seconds ). 1. Power starts ( within 2.5 seconds ).
2. The controller enters the failure mode. See section 3-17 for failure mode 2. The controller enters the failure mode. See section 3-17 for failure mode
descriptions. descriptions.
3. The controller enters the manual mode. See section 3-23 for manual mode 3. The controller enters the manual mode. See section 3-23 for manual mode
descriptions. descriptions.
4. The controller enters the calibration mode. See chapter 6 for calibration 4. The controller enters the calibration mode. See chapter 6 for calibration
mode descriptions. mode descriptions.
As the bumpless transfer is activated, the controller will transfer to open-loop As the bumpless transfer is activated, the controller will transfer to open-loop
control and uses the previous averaging value of MV1 and MV2 to continue control and uses the previous averaging value of MV1 and MV2 to continue
control. control.
Without Bumpless Transfer Without Bumpless Transfer
PV
Set point Set point
Since the hardware and software need time to be initialized, the control is Since the hardware and software need time to be initialized, the control is
abnormal as the power is recovered and results in a large disturbance to abnormal as the power is recovered and results in a large disturbance to
the process. During the sensor breaks, the process loses power. the process. During the sensor breaks, the process loses power.
With Bumpless Transfer With Bumpless Transfer
PV
Set point Set point
After bumpless transfer configured, the correct control variable is applied After bumpless transfer configured, the correct control variable is applied
immediately as the power is recovered, the disturbance is small. During the immediately as the power is recovered, the disturbance is small. During the
sensor breaks, the controller continues to control by using its previous value. If sensor breaks, the controller continues to control by using its previous value. If
the load doesn't change, the process will remain stable. Thereafter, once the the load doesn't change, the process will remain stable. Thereafter, once the
load changes, the process may run away. load changes, the process may run away.
bumpless transfer for a longer time. bumpless transfer for a longer time.
should be used to announce the operator when the system fails. For should be used to announce the operator when the system fails. For
a Sensor Break Alarm, if configured, will switch to failure state and announces a Sensor Break Alarm, if configured, will switch to failure state and announces
the operator to use manual control or take a proper security action when the the operator to use manual control or take a proper security action when the
system enters failure mode. system enters failure mode.
Power interrupted Power interrupted
Sensor break Sensor break
Large Large
deviation deviation
Power interrupted Power interrupted
Sensor break Sensor break
Load varies Load varies
Small Small
deviation deviation
Therefore, you should not rely on a Therefore, you should not rely on a
For fail safe reason, an additional alarm For fail safe reason, an additional alarm
UM25001C
Bumpless Transfer Setup : Bumpless Transfer Setup :
1. O1FT = BPLS 1. O1FT = BPLS
2. O2FT = BPLS 2. O2FT = BPLS
Bumpless Transfer Occurs as : Bumpless Transfer Occurs as :
1. Power Starts ( within 2.5 seconds ) 1. Power Starts ( within 2.5 seconds )
2. Failure mode is activated 2. Failure mode is activated
3. Manual mode is activated 3. Manual mode is activated
4. Calibration mode is activated 4. Calibration mode is activated
Figure 3.21 Benefits of Bumpless Figure 3.21 Benefits of Bumpless
Time
Time
Warning :After system fails, Warning :After system fails,
never depend on bumpless never depend on bumpless
transfer for a long time, transfer for a long time,
otherwise it might cause a otherwise it might cause a
problem to the system to run problem to the system to run
away. away.
example example , ,
Transfer Transfer
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