IG-267-EN versión 01; 07/04/2017
20
Protection functions General Instructions
ekor.rpa
4. Protection functions
4.1. Overcurrent units
The ekor.rpa-100 systems are fitted with the following
overcurrent protection units:
Phases:
• Six phase overcurrent timed units (3 x 51.3 x 51(2)).
• Three phase overcurrent instantaneous units (3 x 50).
Neutral (Calculated):
• Two neutral timed overcurrent units (1 x 51N, 1 x 51(2)
N).
• A neutral instantaneous overcurrent unit (1 x 50N).
Sensitive neutral (measured):
• Two sensitive neutral timed overcurrent units (1 x 51NS,
1 x 51(2)NS).
• A sensitive neutral instantaneous overcurrent unit (1 x
50NS).
4.1.1. Timed overcurrent units
The phase, neutral and sensitive neutral timed units start
up if the fundamental value of the magnitude for each unit
exceeds the value 1.05 times the adjusted start-up, and are
reset when this value is below 0.95 times the adjusted value.
Tripping takes place if the unit is started up for the time set.
This time may be adjusted by selecting different types of
curve, in accordance with IEC and ANSI Standards.
The curves implemented in the ekor.rpa-100 units are:
IEC CURVES
• IEC DT: Defined time
• IEC NI: Normally inverse curve
• IEC VI: Very inverse curve
• IEC EI: Extremely inverse curve
• IEC LTI: Long time inverse curve
• IEC STI: Short time inverse curve
ANSI CURVES
• ANSI LI: Long time inverse curve
• ANSI NI: Normally inverse curve
• ANSI VI: Very inverse curve
• ANSI EI: Extremely inverse curve
These curves are detailed in the ANNEX section.
The settings for the timed units are:
• Enabling the unit: Enable/disable the unit (ON/OFF).
• Starting up the unit: Unit starting current. Variable
ranges in accordance with current transformers used.
• Time curve: Curve type (IEC DT, IEC NI, IEC VI, IEC EI, IEC
LTI, IEC STI, ANSI LI, ANSI NI, ANSI VI, ANSI EI).
• Time index: Time index, also known as time dial (from
0.05 to 1.60). This setting applies to all curve types
except for IEC DT.
• Fixed time: Unit tripping time (from 0.00 s to 100.00 s).
This setting only applies to IEC DT type curves.
• Torque control: Directional tripping mask (OFF,
FORWARD or REVERSE). To indicate the direction for
tripping:
- OFF: Regardless of the direction, the relevant
overcurrent unit will trip if the overcurrent conditions
are met.
- FORWARD: The corresponding overcurrent unit
will trip whenever the overcurrent conditions are
met, and the directional unit will give the FORWARD
signal.
- REVERSE: The corresponding overcurrent unit will
trip whenever the overcurrent conditions are met,
and the directional unit will give the REVERSE signal.
This setting will only be found in ekor.rpa-100 units
model 120.
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