Ice NP900 Series User guide


Application Guide - NP900 Series 2 (504)
Revision Date Changes Written by Checked by
A 07/11/2017 First issue ASI RBI
-
Read these instructions carefully and inspect the equipment to become familiar with it
before trying to install, operate, service or maintain it.
Electrical equipment should be installed, operated, serviced, and maintained only by
qualified personnel. Local safety regulations should be followed. No responsibility is
assumed by ICE for any consequences arising out of the use of this material.
We reserve right to changes without further notice.

Application Guide - NP900 Series 3 (504)
TABLE OF CONTENTS
1ABBREVIATIONS .............................................................................................................5
2GENERAL.........................................................................................................................6
3FUNCTIONS OF NP900....................................................................................................7
3.1 Measurements .......................................................................................................7
3.1.1 Current measurement and scaling ................................................................7
3.1.2 Voltage measurement and scaling .............................................................. 20
3.1.3 Frequency tracking and sampling ............................................................... 31
3.1.4 Power and energy calculation ..................................................................... 34
3.2 Protection functions .............................................................................................42
3.2.1 General properties of a protection function ................................................. 42
3.2.2 Non-directional over current I> (50/51)........................................................ 58
3.2.3 Non-directional earth fault I0> (50N/51N).................................................... 64
3.2.4 Directional over current IDir> (67) ............................................................... 68
3.2.5 Directional earth fault I0Dir> (67N).............................................................. 75
3.2.6 Intermittent earth fault I0Int> (67NT) ........................................................... 83
3.2.7 Current unbalance I2> (46/46R).................................................................. 92
3.2.8 Harmonic over current IH> (50H/51H/68H) ................................................. 100
3.2.9 Circuit breaker failure protection (CBFP) (50BF)....................................... 106
3.2.10 Restricted earth fault / cable end differential (REF) I0D> (87N) ................. 118
3.2.11 Thermal overload protection for feeders TF> (49F) ................................... 126
3.2.12 Arc fault ARCI> (50ARC/50NARC) ........................................................... 144
3.2.13 Over voltage U> (59) ................................................................................ 151
3.2.14 Under voltage U< (27)............................................................................... 155
3.2.15 Vector jump (78) ....................................................................................... 162
3.2.16 Positive sequence over- and under voltage U1>/< (59P/27P/47) .............. 167
3.2.17 Neutral voltage U0> (59N) ........................................................................ 176
3.2.18 Over power (32)........................................................................................ 182
3.2.19 Under power (37)...................................................................................... 186
3.2.20 Reverse power (32R)................................................................................ 190
3.2.21 Over- and under frequency f>/< (81O/81U)............................................... 194
3.2.22 Rate of change of frequency (ROCOF) (81R) ........................................... 200
3.2.23 Programmable stage (99) ......................................................................... 205
3.3 Motor protection module .................................................................................... 217
3.3.1 Motor status monitoring (MST).................................................................. 217
3.3.2 Thermal overload protection for machines Tm> (49M)............................... 226

Application Guide - NP900 Series 4 (504)
3.3.3 Motor start / locked rotor monitoring (LRC) IST> (48, 14)........................... 255
3.3.4 Frequent start protection (FSP) N> (66).................................................... 265
3.3.5 Under current I< (37) ................................................................................ 270
3.3.6 Mechanical jam protection Im> (51M)........................................................ 274
3.3.7 Resistance temperature detectors (RTD) (49T) ........................................ 280
3.4 Generator protection module ............................................................................. 285
3.4.1 Machine thermal protection (49M)............................................................. 285
3.4.2 Under excitation Q< (40)........................................................................... 285
3.4.3 Under impedance Z< (21G) ...................................................................... 290
3.4.4 Voltage restrained overcurrent (51V) ........................................................ 292
3.4.5 Volts-per-Hertz over excitation (24)........................................................... 296
3.4.6 Stator earth fault (64S).............................................................................. 302
3.5 Transformer protection module .......................................................................... 307
3.5.1 Transformer status monitoring functions ................................................... 307
3.5.2 Differential protection ID> (87) .................................................................. 313
3.5.3 Thermal overload for transformer (49T) .................................................... 357
3.5.4 Volts-per-Hertz over excitation (24)........................................................... 367
3.6 Control functions................................................................................................ 368
3.6.1 Setting group selection (SGS)................................................................... 368
3.6.2 Object control and monitoring (OBJ) ......................................................... 376
3.6.3 Synchro-check function Δf, ΔU, Δφ........................................................... 385
3.6.4 Auto-reclosing 0 1 (79) ......................................................................... 396
3.6.5 Cold load pick-up (CLPU) (68) .................................................................. 427
3.6.6 Switch on to fault (SOTF).......................................................................... 436
3.6.7 Voltage regulator (90) ............................................................................... 438
3.7 Monitoring functions........................................................................................... 461
3.7.1 Current transformer supervision (CTS) ..................................................... 461
3.7.2 Fuse failure (VTS) (60) ............................................................................. 471
3.7.3 Disturbance recorder (DR) ........................................................................ 474
3.7.4 Measurement recorder.............................................................................. 486
3.7.5 Circuit breaker wear -monitor (CBW) ........................................................ 487
3.7.6 Total harmonic distortion monitor (THD) ................................................... 492
3.7.7 Alarm ........................................................................................................ 498
3.7.8 Fault locator (21FL)................................................................................... 500

Application Guide - NP900 Series 5 (504)
1ABBREVIATIONS
CB – Circuit breaker
CBFP – Circuit breaker failure protection
CT – Current transformer
CPU – Central processing unit
EMC – Electromagnetic compatibility
HMI – Human machine interface
HW – Hardware
IED – Intelligent electronic device
IO – Input output
LED – Light emitting diode
LV – Low voltage
MV – Medium voltage
NC – Normally closed
NO – Normally open
RMS – Root mean square
SF – System failure
TMS – Time multiplier setting
TRMS – True root mean square
VAC – Voltage alternating current
VDC – Voltage direct current
SW – Software
uP – Microprocessor

Application Guide - NP900 Series 6 (504)
2GENERAL
Electrical networks are a building brick of our economic life. Generation, transmission,
distribution and use of the electrical energy in safe conditions are fundamental for the
growth of cities and industries.
Perfect control over the electrical networks, from production to final use is an important
issue. It is based upon cost control for production and maintenance.
Faced with ever more demanding expectations, ICE chose to design, produce and
distribute a complete range of equipment’s supporting the implementation of the
intelligence and connections required, for a fully optimized management of electrical
networks.
Because it uses the most advanced digital technologies for local information processing,
field buses for transmission, the most powerful industrial computers to drive and supervise
the electrical networks, ICE demonstrates via its accomplishments in the field of industrial
reliability how it can apply its technologies to the other fields of the electrical energy
industry management.

Application Guide - NP900 Series 7 (504)
3FUNCTIONS OF NP900
3.1 MEASUREMENTS
3.1.1 CURRENT MEASUREMENT AND SCALING
In NP900 series current measurement module (CT-module) is used for measuring the
currents from current transformers and processing the measured currents to
measurement database and for use of measurement- and protection functions. For the
measurements to be correct it is essential to understand the concept of the NP900 series
IEDs current measurements.
-PRI
oPrimary current, the current
which flows in the primary circuit
and through primary side of the
current transformer.
-SEC
o
Secondary current, the current
which the current transformer
transforms according to its ratios.
This current is measured by the
protection IED.
-NOM
oNominal
primary current of the
load. Load in this means can be
any electrical apparatus which
produces or consumes electricity
and has rated value for when it is
producing or consuming
electricity in its rated conditions.
Figure 3.1.1-1 Current measurement terminology in NP900 platform
For the measurements to be correct it needs to be made sure that the measurement
signals are connected to correct inputs, current direction is connected correctly and the
scaling is set correctly.
For the scaling relay calculates scaling factors based onto the set CT primary, secondary
and nominal current values. Relay measures secondary current which in this case mean
the current output from the current transformer which is installed into the primary circuit of

Application Guide - NP900 Series 8 (504)
the application. In order the relay to “know” primary and per unit values it needs to be told
the current transformer rated primary and secondary currents. In case of motor or any
specific electrical apparatus protection the relay needs to be told also the motors nominal
current in order that the settings can be per unitized to apparatus nominal not to CT
nominal (This is not absolutely mandatory, in some relays it is still needed to calculate
correct settings manually. Setting the relay nominal current makes the motor protection a
lot easier and straight forward. In modern protection IED like NP900 series devices this
scaling calculation is done internally after the current transformer primary, secondary and
motor nominal currents are given). Also in the NP900 series feeder protection IEDs the
scaling can be set according to protected object nominal current.
Normally the primary current ratings for phase current transformers are 10A, 12.5A, 15A,
20A, 25A, 30A, 40A, 50A, 60A and 75A and their decimal multiples, while normal
secondary current ratings are 1 and 5A. For NP900 series devices also other, non-
standard ratings can be directly connected since the scaling settings are flexible in large
ranges. For ring core current transformers the ratings may be different. Ring core current
transformers are commonly used for sensitive earth fault protection and their rated
secondary may be as low as 0.2 A in some cases.
In following chapter is given example for the scaling of the relay measurements to the
example current transformers and system load.
3.1.1.1 CT SCALING EXAMPLE
The connection of CTs to the IED measurement inputs and the ratings of the current
transformers and load nominal current are as in following figure.

Application Guide - NP900 Series 9 (504)
Figure 3.1.1.1-2 Example connection.
Initial data of the connection and the ratings are presented in following table.
Table 3.1.1.1-1 Initial data from example connection.
Phase current CT:
CT primary 100A
CT secondary 5A
Ring core CT in Input I02:
I0CT primary 10A
I0CT secondary 1A
Load nominal 36A
Phase currents are connected to residual connection into the I01 residual input.
Phase current CT secondary currents starpoint is towards the line.
For the scaling of the currents to per unit values for the protections selection needs to be
made now if the protected object nominal current or the CT primary value should be the
base for per unitizing.
If the per unit scaling is wanted to be according to the CT values then “Scale meas to In”
is set to “CT nom p.u.” As presented in the figure below.

Application Guide - NP900 Series 10 (504)
Figure 3.1.1.1-3 Phase current transformer scalings to CT nominal.
After the settings are input to the IED, scaling factors are also calculated and displayed for
the user. Scaling factor P/S tells the CT primary to secondary ratio, CT scaling factor to
NOM tells the scaling factor to nominal current (in this case it should be 1 since the
selected nominal current is the phase CT nominal). Per unit scaling factors to primary and
secondary values are also shown. In this case the scaling factors are directly the set
primary and secondary currents of the set CT.
If the settings would be wanted to be scaled to load nominal then the selection “Scale
meas to In” would be set to “Object In p.u.”
Figure 3.1.1.1-4 Phase current transformer scalings to protected object nominal current.
When measurement scaling is made to the protected object nominal current, the object
nominal current needs also to be set into the “Nominal current In” input. The differences in

Application Guide - NP900 Series 11 (504)
the used scaling factors can now be seen. Primary to secondary ratio is directly the ratio
of the set CT ratios, CT scaling factor to nominal is now the set CT primary to nominal
current ratio, per unit scalings to primary is changed now to nominal current and the
secondary per unit factor is calculated accordingly to the given ratio of CT primary to
object nominal current.
If coarse residual current (I01) is wanted to be used for CT sum input then it should be set
to phase current CT ratings 100/1A.
Figure 3.1.1.1-5 Residual current I01 scaling to summing connection.
For the sensitive residual current (I02) measurement is set directly 10/1A rated currents.
Figure 3.1.1.1-6 Residual current I02 scaling to ring core CT input.
If the scaling was made to CT primary or to object nominal current the measurements will
look as follows with nominal current feeding:
Figure 3.1.1.1-7 Scalings to CT nominal.

Application Guide - NP900 Series 12 (504)
Figure 3.1.1.1-8 Scalings to protected object nominal current.
As seen from the examples the primary and secondary currents will be displayed as
actual values so the scaling selection does not have effect to that. Only effect is now that
the per unit system in the relay is scaled to either transformer nominal or the protected
object nominal and this makes the settings input for the protected object straight forward.
3.1.1.2 ZCT SCALING EXAMPLE
Figure 3.1.1.2-9 If zero sequence current transformer is used it should be connected to
I02 channel which has lower CT scaling ranges.

Application Guide - NP900 Series 13 (504)
Figure 3.1.1.2-10 Setting example of zero sequence current transformer application.
Figure 3.1.1.2-11 With current transformer ratio of 200mA/1.5mA earthfault protection
setting 1*I0n will make the function pick-up at 200mA primary current.
3.1.1.3 TROUBLESHOOTING
It is possible that for some reason the measured currents may not be as expected. For
these cases following checks may be helpful.
Problem
Check / Resolution
Measured current amplitude in all phases does not
match for what is injected.
Scaling settings may be wrong, check from
Measurement, Transformers, Phase CT scaling that the
settings match for what is expected. Also check that the
scaling measurement to In is set accordingly either to
“Object In“or CT nominal. If working with CT:s, if
possible check the actual ratings from the CT:s as well,
since in some cases the actual CT:s may have been
changed from the original plan for some reason.
Measured current amplitude does not match for one
measured phase or calculated I0 is measured when
there should not be any.
Check wiring connections from injection device or CTs
to the IED. NOTE: If working with CTs which are in
energized system extreme caution should be practiced
when checking connections. Opened CT secondary
circuit may generate dangerously high voltages.
“Buzzing” sound from connector can indicate open
circuit.
Measured current amplitudes are all ok and equal but
the angles are strange.
Phase currents are connected into the measurement
module, but the order or polarity of one or all phases is

Application Guide - NP900 Series 14 (504)
Phase unbalance protection trips immediately when it
is activated.
Earth fault protection trips immediately when it is
activated.
incorrect.
Go to Measurement, Phasors and check the current
Phasors diagram.
When all is correctly connected the diagram should
look as below with symmetric feeding:
In following rows few most common cases are
presented
Phase polarity problems are easy to find since the vector diagram points out the opposite polarity in the wrongly
connected phase.
Phase L1 (A) polarity incorrect.
Measurements:
Phase currents
Sequence currents
IL1: 1.00 xIn / 0.00 deg
IL2: 1.00 xIn / 60.00 deg
IL3: 1.00 xIn / 300.00 deg
I1: 0.33 xIn / 180.00 deg
I2: 0.67 xIn / 0.00 deg
I0Calc: 0.67 xIn / 0.00 deg
Resolution:
-Change wires to opposite in CT module connectors 1
– 2
-Or from the Transformers, Phase CT scaling select
IL1 polarity to “Invert”.
Phase L2 (B) polarity incorrect.
Measurements:
Phase currents
Sequence currents
IL1: 1.00 xIn / 0.00 deg
IL2: 1.00 xIn / 60.00 deg
IL3: 1.00 xIn / 120.00 deg
I1: 0.33 xIn / 0.00 deg
I2: 0.67 xIn / -60.00 deg
I0Calc: 0.67 xIn / 60.00 deg
Resolution:
-Change wires to opposite in CT module connectors 3
– 4
-Or from the Transformers, Phase CT scaling select
IL2 polarity to “Invert”.
Phase L3 (C) polarity incorrect.
Measurements:
Phase currents
Sequence currents
IL1: 1.00 xIn / 0.00 deg
IL2: 1.00 xIn / 240.00 deg
IL3: 1.00 xIn / 300.00 deg
I1: 0.33 xIn / 0.00 deg
I2: 0.67 xIn / 60.00 deg
I0Calc: 0.67 xIn / -60.00 de
Resolution:
-Change wires to opposite in CT module connectors 5
– 6
-Or from the Transformers, Phase CT scaling select
IL3 polarity to “Invert”.

Application Guide - NP900 Series 15 (504)
Network rotation / mixed phases problem might be difficult to find since the measurement result shall always be
the same in the relay. If two phases are mixed together the network rotation shall always look like IL1-IL3-IL2 and
the measured negative sequence current shall be always 1.00 per unit if this is the case.
Phase L1 (A) and L2 (B) switch place (network rotation
wrong).
Measurements:
Phase currents
Sequence currents
IL1: 1.00 xIn / 0.00 deg
IL2: 1.00 xIn / 120.00 deg
IL3: 1.00 xIn / 240.00 deg
I1: 0.00 xIn / 0.00 deg
I2: 1.00 xIn / 0.00 deg
I0Calc: 0.00 xIn / 0.00 deg
Resolution:
-Change wires to opposite in CT module connectors 1
- 3
Phase L2 (B) and L3 (C) switch place (network rotation
wrong).
Measurements:
Phase currents
Sequence currents
IL1: 1.00 xIn / 0.00 deg
IL2: 1.00 xIn / 120.00 deg
IL3: 1.00 xIn / 240.00 deg
I1: 0.00 xIn / 0.00 deg
I2: 1.00 xIn / 0.00 deg
I0Calc: 0.00 xIn / 0.00 deg
Resolution:
-Change wires to opposite in CT module connectors 3
- 5
Phase L3 (C) and L1 (A) switch place (network rotation
wrong).
Measurements:
Phase currents
Sequence currents
IL1: 1.00 xIn / 0.00 deg
IL2: 1.00 xIn / 120.00 deg
IL3: 1.00 xIn / 240.00 deg
I1: 0.00 xIn / 0.00 deg
I2: 1.00 xIn / 0.00 deg
I0Calc: 0.00 xIn / 0.00 deg
Resolution:
-Change wires to opposite in CT module connectors 1
- 5
3.1.1.4 SETTINGS
Table 3.1.1.4-2 Settings of the Phase CT scaling in NP900.
Name
Range
Step
Default
Description
Scale meas to In
0:CT nom p.u.
1:Object In p.u.
-
0:CT nom p.u.
Selection of the IED per unit system
scaling reference, either the set phase
current CT primary or protected object
nominal current.
Phase CT primary
1…5000.0 A
0.1A
100.0A
Rated primary current of the CT in
amperes.
Phase CT secondary
0.2…10.0 A
0.1A
5.0A
Rated secondary current of the CT in
amperes.
Nominal current In
1…5000A
0.01A
100.00A
Protected object nominal current in
amperes. (This setting is visible if “Scale
meas to In” setting is set to “Object In
p.u.”)
IL1 Polarity
0:-
1:Invert
-
0:-
IL1 (first current) measurement channel
polarity (direction) selection. Default
setting is that positive current flow is from

Application Guide - NP900 Series 16 (504)
connector 1 to connector 2 and the
secondary currents starpoint is towards
line.
IL2 Polarity
0:-
1:Invert
-
0:-
IL2 (second current) measurement
channel polarity (direction) selection.
Default setting is that positive current flow
is from connector 3 to connector 4 and
the secondary currents starpoint is
towards line.
IL3 Polarity
0:-
1:Invert
-
0:-
IL3 (third current) measurement channel
polarity (direction) selection. Default
setting is that positive current flow is from
connector 5 to connector 6 and the
secondary currents starpoint is towards
line.
CT scaling factor P/S
-
-
-
IED feedback value, this is the calculated
scaling factor for primary /secondary
current ratio
CT scaling factor
NOM
-
-
-
IED feedback value, this is the calculated
ratio in between of set primary and
nominal currents.
Ipu scaling primary
-
-
-
IED feedback value, scaling factor from
p.u. value to primary current.
Ipu scaling
secondary
-
-
-
IED feedback value, scaling factor from
p.u. value to secondary current.
Table 3.1.1.4-3 Settings of the residual I01 CT scaling in NP900.
Name
Range
Step
Default
Description
I01 CT primary
1…5000.0 A
0.1A
100.0A
Rated primary current of the CT in
amperes.
I01 CT secondary
0.2…10.0 A
0.1A
5.0A
Rated secondary current of the CT in
amperes.
I01 Polarity
0:-
1:Invert
-
0:-
I01 (coarse residual) measurement
channel polarity (direction) selection.
Default setting is that positive current flow
is from connector 7 to connector 8.
CT scaling factor P/S
-
-
-
IED feedback value, this is the calculated
scaling factor for primary /secondary
current ratio
Table 3.1.1.4-4 Settings of the residual I02 CT scaling in NP900.
Name
Range
Step
Default
Description
I02 CT primary
1…5000.0 A
0.1A
100.0A
Rated primary current of the CT in
amperes.
I02 CT secondary
0.0001…10.0 A
0.0001A
5.0A
Rated secondary current of the CT in
amperes.
I02 Polarity
0:-
1:Invert
-
0:-
I02 (fine residual) measurement channel
polarity (direction) selection. Default
setting is that positive current flow is from
connector 9 to connector 10.
CT scaling factor P/S
-
-
-
IED feedback value, this is the calculated
scaling factor for primary /secondary
current ratio

Application Guide - NP900 Series 17 (504)
3.1.1.5 MEASUREMENTS
Following measurements are available from the measured current channels.
Table 3.1.1.5-5 Per unit phase current measurements in NP900.
Name
Range
Step
Description
Phase current ILx
0.00…1250.0 xIn
0.01xIn
Per unit measurement from each phase
current channel fundamental frequency
RMS current.
Phase current ILx TRMS
0.00…1250.0 xIn
0.01xIn
Per unit measurement from each current
channel TRMS current including
harmonics up to 31
st
.
Peak to peak current ILx
0.00…500.0 xIn
0.01xIn
Per unit measurement peak to peak
current from each phase current
measurement channel.
Table 3.1.1.5-6 Primary phase current measurements in NP900.
Name
Range
Step
Description
Primary Phase current
ILx
0.00…1000000.0A
0.01A
Primary measurement from each phase
current channel fundamental frequency
RMS current.
Phase current ILx TRMS
pri
0.00…1000000.0A
0.01A
Primary measurement from each current
channel TRMS current including
harmonics up to 31
st
.
Table 3.1.1.5-7 Secondary phase current measurements in NP900.
Name
Range
Step
Description
Secondary Phase current
ILx
0.00…300.0A
0.01A
Secondary measurement from each
phase current channel fundamental
frequency RMS current.
Phase current ILx TRMS
sec
0.00…300.0A
0.01A
Secondary measurement from each
current channel TRMS current including
harmonics up to 31
st
.
Table 3.1.1.5-8 Phase current angles measurements in NP900.
Name
Range
Step
Description
Phase angle ILx
0.00…360.00 deg
0.01deg
Phase angle measurement of the three
phase current inputs.

Application Guide - NP900 Series 18 (504)
Table 3.1.1.5-9 Per unit residual current measurements in NP900.
Name
Range
Step
Description
Residual current I01
0.00…1250.0 xIn
0.01xIn
Per unit measurement from residual
current channel I01 fundamental
frequency RMS current.
Residual current I02
0.00…1250.0 xIn
0.01xIn
Per unit measurement from residual
current channel I02 fundamental
frequency RMS current.
Calculated I0
0.00…1250.0 xIn
0.01xIn
Per unit measurement from calculated I0
current fundamental frequency RMS
current.
Phase current I01 TRMS
0.00…1250.0 xIn
0.01xIn
Per unit measurement from I01 residual
current channel TRMS current including
harmonics up to 31
st
.
Phase current I02 TRMS
0.00…1250.0 xIn
0.01xIn
Per unit measurement from I02 residual
current channel TRMS current including
harmonics up to 31
st
.
Peak to peak current I01
0.00…500.0 xIn
0.01xIn
Per unit measurement peak to peak
current from I01 residual current
measurement channel.
Peak to peak current I02
0.00…500.0 xIn
0.01xIn
Per unit measurement peak to peak
current from I02 residual current
measurement channel.
Table 3.1.1.5-10 Primary residual current measurements in NP900.
Name
Range
Step
Description
Primary residual current
I01
0.00…1000000.0A
0.01A
Primary measurement from residual
current channel I01 fundamental
frequency RMS current.
Primary residual current
I02
0.00…1000000.0A
0.01A
Primary measurement from residual
current channel I02 fundamental
frequency RMS current.
Primary calculated I0
0.00…1000000.0A
0.01A
Primary measurement from calculated I0
fundamental frequency RMS current.
Residual current I01
TRMS pri
0.00…1000000.0A
0.01A
Primary measurement from residual
current channel I01 TRMS current
including harmonics up to 31
st
.
Residual current I02
TRMS pri
0.00…1000000.0A
0.01A
Primary measurement from residual
current channel I02 TRMS current
including harmonics up to 31
st
.

Application Guide - NP900 Series 19 (504)
Table 3.1.1.5-11 Secondary residual current measurements in NP900.
Name
Range
Step
Description
Secondary residual
current I01
0.00…300.0A
0.01A
Secondary measurement from residual
current channel I01 fundamental
frequency RMS current.
Secondary residual
current I02
0.00…300.0A
0.01A
Secondary measurement from residual
current channel I02 fundamental
frequency RMS current.
Secondary calculated I0
0.00…300.0A
0.01A
Secondary measurement from calculated
I0 fundamental frequency RMS current.
Residual current I01
TRMS sec
0.00…300.0A
0.01A
Secondary measurement from residual
current channel I01 TRMS current
including harmonics up to 31
st
.
Residual current I02
TRMS sec
0.00…300.0A
0.01A
Secondary measurement from residual
current channel I02 TRMS current
including harmonics up to 31
st
.
Table 3.1.1.5-12 Residual current angles measurements in NP900.
Name
Range
Step
Description
Residual current angle
I01
0.00…360.00 deg
0.01deg
Residual current angle measurement of
the I01 current input.
Residual current angle
I02
0.00…360.00 deg
0.01deg
Residual current angle measurement of
the I02 current input.
Calculated I0 phase
angle
0.00…360.00 deg
0.01deg
Calculated residual current angle
measurement.
Table 3.1.1.5-13 Per unit sequence current measurements in NP900.
Name
Range
Step
Description
Positive sequence
current
0.00…1250.0 xIn
0.01xIn
Per unit measurement from calculated
positive sequence current
Negative sequence
current
0.00…1250.0 xIn
0.01xIn
Per unit measurement from calculated
negative sequence current
Zero sequence current
0.00…1250.0 xIn
0.01xIn
Per unit measurement from calculated
zero sequence current
Table 3.1.1.5-14 Primary sequence current measurements in NP900.
Name
Range
Step
Description
Primary Positive
sequence current
0.00…1000000.0A
0.01A
Primary measurement from calculated
positive sequence current
Primary Negative
sequence current
0.00…1000000.0A
0.01A
Primary measurement from calculated
negative sequence current
Primary Zero sequence
current
0.00…1000000.0A
0.01A
Primary measurement from calculated
zero sequence current
Table 3.1.1.5-15 Secondary sequence current measurements in NP900.
Name
Range
Step
Description
Secondary Positive
sequence current
0.00…300.0A
0.01A
Secondary measurement from calculated
positive sequence current
Secondary Negative
sequence current
0.00…300.0A
0.01A
Secondary measurement from calculated
negative sequence current
Secondary Zero
sequence current
0.00…300.0A
0.01A
Secondary measurement from calculated
zero sequence current

Application Guide - NP900 Series 20 (504)
Table 3.1.1.5-16 Sequence current angle measurements in NP900.
Name
Range
Step
Description
Positive sequence
current angle
0.00…360.0deg
0.01deg
Calculated positive sequence current
angle
Negative sequence
current angle
0.00…360.0deg
0.01deg
Calculated negative sequence current
angle
Zero sequence current
angle
0.00…360.0deg
0.01deg
Calculated zero sequence current angle
Table 3.1.1.5-17 Harmonic current measurements in NP900.
Name
Range
Step
Description
IL1 Harmonics
IL1 fund…IL1 31harm
0.00…1000000.0A
0.01A
Per unit, primary and secondary
harmonics per component for current
input IL1
IL2 Harmonics
IL2 fund…IL2 31harm
0.00…1000000.0A
0.01A
Per unit, primary and secondary
harmonics per component for current
input IL2
IL3 Harmonics
IL3 fund…IL3 31harm
0.00…1000000.0A
0.01A
Per unit, primary and secondary
harmonics per component for current
input IL3
I01 Harmonics
I01 fund…I01 31harm
0.00…1000000.0A
0.01A
Per unit, primary and secondary
harmonics per component for current
input I01
I02 Harmonics
I02 fund…I02 31harm
0.00…1000000.0A
0.01A
Per unit, primary and secondary
harmonics per component for current
input I02
3.1.2 VOLTAGE MEASUREMENT AND SCALING
In NP900 series voltage measurement module (VT-module) is used for measuring the
voltages from voltage transformers and processing the measured voltages to
measurement database and for use of measurement- and protection functions (protection
function availability depends on IED type). For the measurements to be correct it is
essential to understand the concept of the NP900 series IEDs voltage measurements.
-PRI
o
Primary voltage, the voltage
which flows in the primary circuit
and through primary side of the
voltage transformer.
-SEC
o
Secondary voltage, the voltage
which the voltage transformer
transforms according to the ratio.
This voltage is measured by the
protection IED.
Figure 3.1.2-12 Voltage measurement terminology in NP900 platform
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