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