Tempco TEC-2500, Инструкция по эксплуатации

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3–18 Bumpless Transfer
The bumpless transfer function is available for output 1 and output 2 (provided
that OUT2 is configured as COOL).
Bumpless transfer is enabled by selecting BPLS for O1FT and/or O2FT and
activated as one of the following cases occurs:
1. Power starts (within 2.5 seconds).
2. The controller enters failure mode. See section 3-17 for failure mode
descriptions.
3. The controller enters manual mode. See section 3-23 for manual mode
descriptions.
4. The controller enters calibration mode. See chapter 6 for calibration mode
descriptions.
As 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.
When bumpless transfer is configured, the correct control variable is applied
immediately as power is recovered, and the disturbance is small. During sensor
breaks, the controller continues to control by using its previous value. If the load
doesn't change, the process will remain stable. If the load changes, the process
may run away. Therefore, you should not rely on bumpless transfer for extended
periods of time. For fail safe reasons, an additional alarm should be used to
announce to the operator when the system fails. For example, a sensor break
alarm, if configured, will switch to failure state and tell the operator to use manual
control or take proper security action when the system enters failure mode.
Bumpless transfer setup:
1. O1FT=BPLS
2. O2FT=BPLS
Bumpless transfer occurs as:
1. Power starts (within 2.5 seconds)
2. Failure mode is activated
3. Manual mode is activated
4. Calibration mode is activated
Warning: After the system fails,
never depend on bumpless
transfer for a long time, or it
might cause the system to run
away.