Burkert Type 8611 - Manual (Page 78)

78
FunctionsoftheConfigurationLevel
setting aid:
An unsatisfactory dynamic of the control is improved by increasing the proportional gain [K
p
]. The fol-
lowing must be observed:
In the event of impermissibly high overshoots after set-point value jumps or in the event of an unstable
control, the proportional gain [K
p
] should be reduced.
12.13.3. TREG – setting the controller cycle time
This parameter is only available if quasi-continuous actuating parameters have been selected
(
MODE = PCV, 2P – T or 3P – T).
TREG defines the cycle time in seconds in that a set-point/actual value comparison is regularly executed and a new
manipulated variable is calculated. Within this time the pilot valve will be switched one time.
The parameter TREG has to be set in that way to get an acceptable life time of the valve on the one side and to
avoid an tolerable oscillation of the process value on the other side.
The parameter
TREG should be smaller than the reset time [T
n
]
12.13.4. TN – setting reset time
With this parameter the I-portion of continuous or quasi-continuous control loops can be set.
The reset time [T
n
] in seconds is the time that is required to obtain an equally large change in the manipulated
variable by the I portion, as occurs due to the P portion.
The time it takes for getting about 60 - 70 % of the process value change can be taken as an start value for T
n
.
T
n
can be selected between 0.01 and 999.9 s. When 999.9 is set, the I-portion is deactivated (independent from
decimal place).
12.13.5. DEAD – insensitivity range (dead zone)
This function causes the process controller to respond only from a specific control difference. This protects the
control valves.
The dead zone is entered as an absolute value according to the unit selected in the UNIT menu.
x‘
x x‘
to the controller
Set-point
value (SP)
Control
difference
Process
value
– dead
zone
+
Figure 55: DEAD; Insensitivity range (dead zone)
english
Type 8611