Ashida ADR111A - IDMT Characteristics

Doc ID : ADR111A_IM_01
Ref ID : ADR111A/IM/PLF
Rev No. : 04
Page No. : 57 of 127
ADR111A /
ADR211A
Delay parameter settings. After all the above condition are satisfied, the IED generates the
over current trip.
4.5 IDMT Characteristics
ADR111A/ ADR211A relay provides following inverse time over current characteristics
• Normal Inverse 1 Curve (C1) for 3s
• Normal Inverse 2 Curve (C2) for 1.3s
• Very Inverse Curve (C3)
• Extremely Inverse Curve (C4)
• Extremely Inverse Curve (C4A) as per EE Relays
• Long time Inverse Curve (C5)
• Definite time Over current (C6)
The over current function is programmable as per IDMT characteristic based on IEC
standards. The inverse time delay is calculated with the following mathematical formula:
For IEC Inverse Curve For Extremely Inverse C4A Curve as per EE relays
t =
K* a
I
Iref
b
–
1
t =
K* a
I
Iref
b
– 1
* 1.3
+ 0.22
Where
t = operation time
a = constant
I = Input current
Iref = Current threshold setting
b = Constant
K = Time multiplier setting
Curve Type Description a b
C1 Normal Inverse 1 0.14 0.02
C2 Normal Inverse 2 0.06 0.02
C3 Very Inverse 13.5 1
C4 Extremely inverse 80 2
C4A
Extremely Inverse
(C4A) as per EE Relays
80 2.2
C5 Long Time Inverse 120 1
C6 Definite Time - -