TOHO ELECTRONICS TTM-339 - Manual (Page 15)

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4.16 PV filter setting
4.16.1 PV filter setting
This setting is a function to achieve the CR filter effect on the software by performing a primary delay
calculation on the PV of the input 1.
The filter effect is set with the damping time constant [t].
(Damping time constant is defined as time when PV reaches about 63% in a stepwise change of input.)
* CR filter: Filter of first order lag
Application of a PV filter:
(1) By elimination of high-frequency noise, effect of noise is mitigated when electric noise applies to input.
(2) Response can be delayed for an abrupt change of input.
Input signal
0%
100%
100%
0%
100%
0%
Damping time constant (PdF1)
63%
Read-in input
(No filter)
Read-in input
(With a filter)
4.16.2 B thermocouple/PR40-20 special PV filter setting
This setting is a function for the input 1 to add the PV filter setting time further with a limitation of a particular
range on the B thermocouple and PR40-20.
Filter effect is set by the damping time constant [t].
The effective range of the set filter is as follows:
(1) B thermocouple: In the case of 400

C or below
(2) PR40-20: In the case of below 800

C
100%
0%
100%
0%
Damping time constant (PdF1 + PdFS)
63%
63%
Damping time constant (PdF1)
Normal PV filter
(PV filter setting only)
Special PV filter
Time added for PdFS
Input signal
0%
100%