SMAR CD600 Plus - Page 62

CD600 Plus - User's Manual
4.42
STEAM
FLOW
0t
t
1
TPUT
ERATURE
OU
TEMP
τ
1
- Time constant of the manipulated variable.
Fig 4.15.4 - Open loop response to a step change in steam flow rate (Manipulated Variable).
Note
: Time constant is the time required for the variable to reach 63.2% of the end value for a step
change.
Figure 4.15.5 shows the response of the open loop system to a step variation in the load.
OUTPUT
TEMPERATURE
PRODUCT
FLOW
0
t
t
2
τ
2
- Time constant for a step variation in the product flow rate.
Fig 4.15.5 - Open loop response to a step variation in product flow rate (disturbance)
By comparing
τ
1
and τ
2
, it is possible to determine how the lead-lag block shall work:
- if
τ
1
>τ
2
the block should anticipate the disturbance signal (Lead)
- if
τ
1
<τ
2
the block should delay the disturbance signal (Lag)
The block may also be used to generate a first order Lag.
In this case, use
ATLE=0 and ATLA = desired time constant in the lead lag function.
TYPE MNEM DESCRIPTION RANGE DEFAULT
Address
I LIA Input A
0 to 170/225 to 240
0
I CDLL
Lead-Lag, time constant or
derivative
0 - Derivative
1 - Lead-Lag and time constant
1
P ATLE Lead time - Td (min.) 0.00 - 300.00 min. 0.00 min.
P ATLA Lag time - T (min.) 0.00 - 200.00 min. 0.00 min.
Number of Bytes per Type of Parameter: A = 4 C = 2 L = 2