Non-Directional Inverse Time Delayed Phase And Residual Overcurrent Protection - ABB 650 series Applications Manual

Section 16
Requirements
16.1.6.2
296
³ = × ×
E E 1,5 I
al alreq op
EQUATION1381 V2 EN-US
where:
I The primary operate value (A)
op
I The rated primary CT current (A)
pr
I The rated secondary CT current (A)
sr
I The rated current of the protection IED (A)
r
R The secondary resistance of the CT (W)
ct
R The resistance of the secondary cable and additional load (W). The loop resistance
L
containing the phase and neutral wires, must be used for faults in solidly earthed systems.
The resistance of a single secondary wire should be used for faults in high impedance
earthed systems.
S The burden of an IED current input channel (VA). S
R
S =0.150 VA/channel for I
R
Non-directional inverse time delayed phase and residual overcurrent
protection
The requirement according to Equation
fulfilled if the high set instantaneous or definitive time stage is used. In this case
Equation is the only necessary requirement.
If the inverse time delayed function is the only used overcurrent protection function
the CTs must have a rated equivalent limiting secondary e.m.f. E
than or equal to the required rated equivalent limiting secondary e.m.f. E
below:
³ = × ×
E E 20 I
al alreq op
EQUATION1076 V2 EN-US
where
I The primary current set value of the inverse time function (A)
op
I The rated primary CT current (A)
pr
I The rated secondary CT current (A)
sr
I The rated current of the protection IED (A)
r
Table continues on next page
æ ö
I
S
× + +
sr R
R R
ç ÷
ct L
2
I
I
è ø
pr r
=5 A
r
26 and Equation
æ ö
I S
× + +
sr R
R R
ç ÷
ct L
2
I
I
è ø
pr
r
1MRK 511 423-UEN A
=0.020 VA/channel for I =1 A and
R r
27 does not need to be
that is larger
al
alreq
Bay control REC650 2.2 IEC
Application manual
(Equation 25)
M11339-3 v5
(Equation 26)