ControlMaster CM30, CM50 and CMF310
Universal process controllers,
1
/
4
,
1
/
2
DIN and fieldmount
7 Advanced Level
62
IM/CM/ED–EN Rev. X
7.6.2 Guaranteed Ramp / Soak
If the process variable deviates from the set point by more than the hysteresis value, the program status is
set to
HOLD
and Guaranteed ramp/soak is applied automatically.
Each program has two associated hysteresis values:
Ramp
– applied to ramping segments
and
Soak
– applied to soak segments.
The hysteresis value can be set within the limits '0' to '9999' where a setting of '0' implies that no deviation
from the set point value can be tolerated.
Hysteresis can be applied in one of four ways, with individual settings for each segment:
None
– hysteresis not applied, ramp/soak not guaranteed.
High
– hysteresis applied above set point (Holdback ('HOLD') set if PV > [SP + Hysteresis]).
Low
– hysteresis applied below set point ('HOLD' set if PV < [SP – Hysteresis]).
High/Low
– hysteresis applied above and below set point
(
HOLD
set if PV > [SP + Hysteresis] or PV < [SP – Hysteresis]).
Fig. 7.2 Ramp Types
Note.
Ramping segments can have a different hysteresis to soak segments.
Seg. 1
Seg. 2
Seg. 3
Seg. 4
Seg. 5
Start
Time (hours or minutes)
Holdback active
outside hysteresis
limits
Hysteresis applied Hi-Lo
(above and below the set point)
Process
Hysteresis applied Hi
(above the set point)
End of profile (revert
to local set point or
repeat of profile)
Skip forward
Adjustable ramp rates
Se
t
point (
E
ng.
U
n
its)
Manual pause
Adjustable holdback hysteresis
1. for Ramp segments
2. for Soak segments
Set point