Alstom MiCOM P546 - Page 266

P54x/EN OP/La4 Operation
(OP) 5-92 MiCOM P543, P544, P545 & P546
OP
The relay uses the {A,B,C,D] transmission line equivalent model given the following
parameters:
Total Impedance


zZ
and
Total Susceptance



 90yY
and
Line Length
l
The remote voltage is calculated using the following equations:






























_
_
Is
Vs
AB
CD
Ir
Vr
where
Vr, Ir - Voltage and Current at the receiving end.
Vs, Is - Measured (relay) Voltage and Current at the sending end.
)cosh( lDA 

)sinh( lZcB 

)sinh( lYcC 

ZYl  
Y
Z
Yc
Zc 
1
Y – Total Line Capacitive Charging Susceptance
Zc = Characteristic Impedance of the line (Surge Impedance).
Two stages are included to provide both alarm and trip stages, where required.
Both stages are independently settable where Stage 1 may be selected as either IDMT, DT
or Disabled, within the V1>1 Cmp Funct cell. Stage 2 is DT only and is enabled/disabled in
the V1>Cmp Status cell.
The IDMT characteristic available on the first stage is defined by the following formula:
t = K/(M - 1)
Where:
K = Time multiplier setting
t = Operating time in seconds
M = Remote Calculated voltage / relay setting voltage (PH-)