Hitachi L200 Manual Do Utilizador

L200 Inverter

Oper

ations

and Monitor

ing

The inverter’s PID loop algorithm is configurable for various applications.

PID Output Limit - The PID loop controller has a built-in output limit function. This 
function monitors the difference between the PID setpoint and the loop output (inverter 
output frequency), measured as a percentage of the full scale range of each. The limit is 
specified by parameter A078.

• When the difference |(Setpoint – loop output)| is smaller than or equal to the A078 

limit value, the loop controller operates in its normal linear range.

• When the difference |(Setpoint – loop output)| is larger than the A078 limit value, the 

loop controller changes the output frequency as needed so that the difference does not 
exceed the limit.

The diagram below shows PID setpoint changes and the related output frequency 
behavior when a limit value in A078 exists.

Error Inversion - In typical heating loops or ventilation loops, an increase in energy 
into the process results in an increasing PV. In this case, the Loop Error = (SP – PV). For 
cooling loops, an increase in energy into the process results in a decreasing PV. In this 
case, the Loop Error =  –(SP – PV). Use A077 to configure the error term.

•

•

•

•

Limit value

PID Setpoint

t

A078

Limit value

A078

Output limit

Output limit

%

Limit imposed 

on output

Limit imposed 

on output

Output frequency

∑

PID

Calculation

SP

Error

Freq.

PV from process with 
positive correlation

PV

+

–

A077 = 00

∑

PID

Calculation

SP

Error

Freq.

PV from process with 
negative correlation

PV

–

+

A077 = 01