Operating time for IEC
Operating time for IEEE/ANSI
Reset time for IEC/IEEE/ANSI
Table 3-1 Constants for Operating-Curve and Reset-Curve Characteristics
Operating Curve Reset Curve
Curve Type K α P A B R n
IEC-NI 0.14 0.02 – – – 9.7 2
IEC-VI 13.5 1.0 – – – 43.2 2
IEC-EI 80 2.0 – – – 58.2 2
IEC-LTI 120 1.0 – – – 80 2
IEEE/ANSI-MI – – 0.02 0.0515 0.114 4.85 2
IEEE/ANSI-VI – – 2.0 19.61 0.491 21.6 2
IEEE/ANSI-EI – – 2.0 28.2 0.1217 29.1 2
Where,
I - Fault-current Magnitude
I
S
- Pickup setting
T
m
- Time multiplier
Application and Settings Notes
Gn 51-n Element
Default setting: Disabled
This setting is used to allow the element to be switched on and off if it is not required. A separate setting is
provided for each element. These settings can be used to select the number of elements required.
Parameter State
Description
Disabled
The element is inactive.
Enabled
The element is active.
Gn 51-n Setting
Default setting: 1.00 ⋅ I
s
This setting defines the operating current threshold of the element. The applied phase current must exceed
this setting by a factor of 1.10x for pickup of the element. The operation timing then depends on the selected
characteristic for the element setting. Once the current is below 1.00x the setting value, the element pickup
resets and the reset characteristic is applied. This factor is always applied for 51 elements including when the
characteristic is selected as DTL. Set this setting to suit your individual application.
Gn 51-n Char
Default setting: IEC-NI = IEC normal inverse
Functions
3.4 51 Time-Delayed Overcurrent – Phase
46 Reyrolle, 7SR46 Device, Manual
C53000-G7040-C103-1, Edition 10.2022
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