LG MASTER-K 120S Series User Manual page 114

Chapter 7 Usage of Various Functions
ⓐ Relay response method.
• PID parameters are obtained by On/Off operation during 1 cycle of PV variation.
• PID parameters are obtained by amplitude and period of oscillation
• The On/Off operation will be occur at the SV value.
MV
Period
SV
Amplitude
ⓑ Process reaction curve method(PRC method).
• PID parameters are obtained by step response of process.
• It is useful fo r time 1 order time delay system expressed as following
st
−
Ls
e
K
+
Ts 1
• Obtained parameters may not accurate if the process can't approximated to 1
order system, In this
st
case, use relay response method.
Time delay(L)
4000
MV
80% of SV
63% of SV
Time constant(T)
7-30