G Protection - ABB SACE Emax E1.2 Operating Instructions For The Design Engineer

G Protection

t
G
I4
t4
65 | © 2017 ABB | 1SDH001330R0002 - ECN000058721 Rev. A
Path
Main page - Menus - Protections
Function
G protection protects against a ground fault.
NOTE:
• The protection is available for the LSIG version of the trip unit.
• With Ekip Touch, Ekip Hi-Touch and Ekip G Touch trip units, if the protection is activated the
presence of the S.G.R. toroid has been selected, it is possible to adjust the protection in the
Advanced section, under the Gext item. With Ekip G Hi-Touch both the G and the Gext items
I
are available, in the respective sections.
When the activation threshold is exceeded, the protection trips within a fixed or dynamic time (the time
decreases as the current reading increases).
Parameters
Here is a list of the available parameters:
Parameter Description
To activate/deactivate the protection.
If enabled, the protection is inhibited automatically by the trip unit under two
conditions:
• Disconnection of one or more current sensors.
• Current measured on one of the phases higher than a maximum value.
Enable
It determines the dynamic of the curve and the tripping time, fixed or dynamic
according to the selection:
• t = k (ANSI 50NTD): fixed time trip.
Curve
• t = k / I
The calculation of the tripping time of the inverse time curve is based on a
mathematical expression. The details are provided in the table on page 73.
The value I4 contributes in calculating the tripping time, and also defines the current
value that, if exceeded, activates the protection (with reference to the figure above,
Threshold I4 the threshold is the part of the curve parallel to the y-axis).
It is represented both as an absolute value (Ampere) and as a relative value (In,
nominal value defined by the Rating Plug).
The selected function determines the contribution of t4:
• t = k: t4 is the delay time between the exceeding of the I4 threshold and the
sending of the opening command.
• t = k / I
Time t4 above curve, t4 affects the curve, shifting it along the vertical axis).
The pre-alarm of G protection indicates that the measured current is near to the trip
threshold of the protection.
The prealarm state is activated for currents higher than a threshold that can be set
I4 Prealarm
by the user, and is deactivated in two cases:
Threshold
• Detected current lower than the prealarm threshold.
• Detected current higher than the protection activation threshold.
A value within the 50 % ... 90 % range can be entered, with 1 % steps.
G protection has Trip Enable, Zone Selectivity, Startup Enable, see page 71.
Via Ekip Connect it is also possible to access the blocking functions, see page 72.
IMPORTANT: the maximum current value that deactivates G protection
varies according to the threshold set:
• 8 In (with I4 ≥ 0.8 In)
• 6 In (with 0.5 In ≤ I4 < 0.8 In)
• 4 In (with 0.2 In ≤ I4 < 0.5 In)
• 2 In (with I4 < 0.2 In)
(ANSI 51N): inverse time dynamic tripping.
2
: t4 contributes in calculating the tripping time (with reference to the
2
IMPORTANT: the minimum tripping time for the protection is t4. If
according to the calculation the tripping time is less, it is automatically
limited to t4.
ABB | SACE Emax 2
Ekip Touch protection trip unit | 9 - Touch protections