TOHO ELECTRONICS TTM-339 User Manual

Page 15

- 15 -

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

100%

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



100%

Damping time constant (PdF1 + PdFS)

63%

Damping time constant (PdF1)

Normal PV filter

(PV filter setting only)

Special PV filter

Time added for PdFS

Input signal

100%