Seg XRN2 User manual

XRN2 -Mains decoupling relay

2TB XRN2 02.00 E
Contents
1 Introduction and application
2 Features and characteristics
3 Design
3.1 Connections
3.1.1 Analog input circuits
3.1.2 Blocking input
3.1.3 Reset input
3.1.4 Output relays
3.1.5 Data communication
3.2 Front plate
3.2.1 Indication- and operation elements
3.2.2 Display
3.2.3 LEDs
3.2.4 Front plate XRN2-1
3.2.5 Front plate XRN2-2
3.2.6 Parameter settings
4 Working principle
4.1 Analog circuits
4.2 Digital circuits
4.3 Voltage supervision
4.3.1 Selection of star or delta connection
4.4 Principle of frequency supervision
4.5 Measuring of frequency gradient
(XRN2-2)
4.6 Vector surge supervision (XRN2-1)
4.6.1 Measuring principle of vector surge
supervision
4.7 Voltage threshold value for frequency
measuring
4.8 Blocking function
5 Operation and setting
5.1 Push buttons
5.1.1 Indication of measuring values and
fault data
5.2 DIP switches
5.2.1 Function of the output relays6
5.3 Reset
5.4 Password
5.4.1 Password programming
5.4.2 Using the password
5.5 Relay setting principle
5.5.1 Setting of default parameters
5.5.2 Blocking the protection functions
5.6 Display of software version and
test-TRIP
5.7 Low/High range of functions
blocking and reset
6 Special settings
6.1 Adjustable parameters
6.2 Setting procedure
6.2.1 Parameter setting of over- and
undervoltage supervision
6.2.2 Setting of nominal frequency
6.2.3 Number of measuring repetitions (T)
for frequency functions
6.2.4 Threshold of frequency supervision
6.2.5 Tripping delays for the frequency
elements
6.2.6 Parameter setting of vector surge
supervision (XRN2-1)
6.2.7 Parameter setting of frequency
gradient (XRN2-2)
6.2.8 Voltage threshold value for frequency
and vector surge measuring (df/dt at
XRN2-2)
6.2.9 Adjustment of the slave address
6.2.10 Setting procedure for blocking the
protection functions
6.3 Indication of measuring values
6.3.1 Min./Max.- values
6.4 Reset
7 Relay testing and commissioning
7.1 Power-On
7.2 Testing the output relays
7.3 Checking the set values
7.4 Secondary injection test
7.4.1 Test equipment
7.4.2 Example of test circuit
7.4.3 Checking the input circuits and
measuring functions
7.4.4 Checking the operating and resetting
values of the over/undervoltage
functions
7.4.5 Checking the relay operating time of
the over/undervoltage functions
7.4.6 Checking the operating and resetting
values of the over/underfre-quency
functions
7.4.7 Checking the relay operating time of
the over/underfrequency functions
7.4.8 Checking the vector surge function
7.4.9 Checking the external blocking and
reset functions
7.5 Primary injection test
7.6 Maintenance
8 Technical data
8.1 Measuring input circuits
8.2 Common data
8.3 Setting ranges and steps
8.4 Output relays
8.5 Power supply
8.6 Inputs, blockage and reset
8.7 System data and test specifications
8.8 Relay case
9 Order form

TB XRN2 02.00 E 3
1Introduction and application
The XRN2 is a universal mains decoupling device and
covers the protection requirements from VDEW and
most other utilities for the mains parallel operation of
power stations.
•Over/ and undervoltage protection
•Over/ and underfrequency protection
•Extremely fast decoupling of generator in case of
mains failure (XRN2-1) or
•Rate of change of frequency df/dt (XRN2-2)
Because of combination of three protectional functions
in one device the XRN2 is a very compact mains de-
coupling device. Compared to the standardly used
single devices it has a very good price/performance
ratio.
2Features and characteristics
•Microprocessor technology with watchdog
•Effective analog low pass filter for suppressing har-
monics when measuring frequency and vector surge
•Digital filtering of the measured values by using dis-
crete Fourier analysis to suppress higher harmonics
and d.c. components induced by faults or system op-
erations
•Integrated functions for voltage, frequency and vector
surge in one device as well as single voltage, fre-
quency and vector surge devices.
•Voltage supervision each with two step under-/ and
overvoltage detection
•Frequency supervision with three step under-/ or
overfrequency (user setting)
•Completely independent time settings for voltage and
frequency supervision
•Adjustable voltage threshold value for blocking fre-
quency and vector surge measuring.
•Display of all measuring values and setting parame-
ters for normal operation as well as tripping via a al-
phanumerical display and LEDs
•Storage and indication of the tripping values
•In complience with VDE 0435, part 303 and
IEC 255
•For blocking the individual functions by the external
blocking input, parameters can be set according to
requirement
•User configurable vector surge measurement 1-of-3 or
3-of-3.
•Reliable vector surge measuring by exact calculation
algorithm
This manual is valid for relay software version from
D01_7.23 (for XRN2-1) and D04_7.23 (for XRN2-2)
onwards.

4TB XRN2 02.00 E
3Design
3.1 Connections
Fig.3.1: Connection diagram XRN2-1 and XRN2-2
3.1.1 Analog input circuits
The analog input voltages are galvanically decoupled
by the input transformers of the device, then filtered and
finally fed to the analog digital converter. The measur-
ing circuits can be applied in star or delta connection
(refer to chapter 4.3.1).
3.1.2 Blocking input
The blocking function can be set according to require-
ment. By applying the auxiliary voltage to C1/C1L or
C1/C1H, the previously set relay functions are
blocked (refer to 4.8 and 6.2.10).
3.1.3 Reset input
Please refer to chapter 6.4.
3.1.4 Output relays
The XRN2 has 5 output relays. One trip relay with two
changeover contacts. One alarm relay with two
changeover contacts and three alarm relays with one
changeover contact.
•Tripping 11, 12, 14 and 21, 22, 24
•Indication of over-/ and undervoltage alarm
31, 32, 34 and 41, 42, 44
•Indication of over-/ and underfrequency alarm
51, 52, 54
•Indication of vector surge 61, 62, 64 (XRN2-1) or
df/dt-alarm (XRN2-2)
•Indication self supervision (internal fault of the unit)
71, 72, 74
All trip and alarm relays are normally-off relays, the re-
lay for self supervision is a normally-on relay.

TB XRN2 02.00 E 5
3.1.5 Data communication
For data communication with a central control system
the XRN2 relay is provided with a serial interface
RS485. Simplified and fast reading and changing of
parameters and measuring values can be achieved by
HTL/PL-Soft3, which will be provided on request to-
gether with the relay.
The XRN2 can be connected to other units of the
PROFESSIONAL LINE via interface. If there are more than
one relay in the system, the last relay of the chain has
to be provided with a line termination resistor.
Fig. 3.2: Connection example with 3 users, XR ... as linked device
Fig. 3.3: Connection example with 3 users, XR ... as last device

6TB XRN2 02.00 E
3.2 Front plate
3.2.1 Indication- and operation elements
The front plate of the XRN2-protection relay comprises
the following operation and indication elements:
•Alphanumerical display (4 Digits)
•Push buttons for setting and other operations
•LEDs for measured value indication and setting
Fig. 3.4: Front plate XRN2

TB XRN2 02.00 E 7
3.2.2 Display
Function Display shows Pressed pushbutton Corresponding
LED
Type of relay
Normal operation SEG all types
Measured operating values Actual measured value
Min. and max. values of
voltage, frequency and
vector surge
<SELECT/RESET> one time
for each value
L1, L2, L3,
f, min, max
∆Θ
df
XRN2-1
XRN2-2
Setting values:
star/delta connection
Y/DELT <SELECT/RESET><+><-> ∆/Y
undervoltage (low set)
tripping delay of low set element
setting value in volt
setting value in seconds
<SELECT/RESET><+><->
one time for each value
U<
tU<
undervoltage (high set)
tripping delay of high set element
setting value in volt
setting value in seconds
<SELECT/RESET><+><->
one time for each value
U<<
tU<<
overvoltage (low set)
tripping delay of low set element
setting value in volt
setting value in seconds
<SELECT/RESET><+><->
one time for each value
U>
tU>
overvoltage (high set)
tripping delay of high set element
setting value in volt
setting value in seconds
<SELECT/RESET><+><->
one time for each value
U>>
tU>>
rated frequency setting value in Hz <SELECT/RESET><+><-> fN
frequency measuring repitition setting value <SELECT/RESET><+><-> T
frequency element f1
tripping delay of frequency element f1
setting value in Hz
setting value in seconds
<SELECT/RESET><+><->
one time for each value
f1
tf1
frequency element f2
tripping delay of frequency element f2
setting value in Hz
setting value in seconds
<SELECT/RESET><+><->
one time for each value
f2
tf2
frequency element f3
tripping delay of frequency element f3
setting value in Hz
setting value in seconds
<SELECT/RESET><+><->
one time for each value
f3
tf3
1-of-3/3-of-3 measurement 1Ph/3Ph <SELECT/RESET><+><-> 1/3 XRN2-1
threshold for vector surge setting value in degree <SELECT/RESET><+><-> ∆Θ XRN2-1
setting value df/dt
measuring repitition df/dt
setting value in Hz/s
setting value in periods
<SELECT/RESET><+><->
one time for each value df
dt
XRN2-2
Blocking EXIT <+> until max. setting value LED of blocked
parameter
Undervoltage blocking of
frequency and vector surge meas-
uring (df/dt for XRN2-2)
setting value in Volt <SELECT/RESET><+><-> f, ∆Θ, df
Slave address of serial interface 1 - 32 <SELECT/RESET><+><-> RS
Recorded fault data:
star--connection:
U1, U2, U3
tripping values in Volt <SELECT/RESET><+><->
one time for each phase
L1, L2, L3,
U<, U<<,
U>, U>>
delta-connection:
U12, U23, U31
tripping values in Volt <SELECT/RESET><+><->
one time for each phase
L1, L2, L3
U<, U<<,
U>, U>>
frequency tripping values in Hz <SELECT/RESET><+><->
one time for each phase
f, f1, f2, f3
rate of change of frequency tripping value in Hz/s <SELECT/RESET><+><-> df XRN2-2
vector surge tripping value in degree <SELECT/RESET><+><->
one time for each phase ∆Θ + L1, L2 or L3 XRN2-1
Save parameter? SAV? <ENTER>
Save parameter! SAV! <ENTER> for about 3 s
Software version First part (e.g. D02-)
Sec. part (e.g. 6.01)
<TRIP>
one time for each part
Manual trip TRI? <TRIP>
three times
Inquire password PSW? <SELECT/RESET>/
<+>/<->/<ENTER>
Relay tripped TRIP <TRIP> or fault tripping
Secret password input XXXX <SELECT/RESET>/
<+>/<->/<ENTER>
System reset SEG <SELECT/RESET>
for about 3 s
Table 3.1: possible indication messages on the display

8TB XRN2 02.00 E
3.2.3 LEDs
All LEDs (except LED RS, min and max) are two-
coloured. The LEDs on the left side, next to the alpha-
numerical display light up green during measuring and
red after tripping.
The LEDs below the push button <SELECT/RESET> are
lit green during setting and inquiry procedure of the set-
ting values which are printed on the left side next to the
LEDs. The LEDs will light up red after activation of the
setting values next to their right side.
The LED marked with letters RS lights up during setting
of the slave address of the device for serial data com-
munication.
3.2.4 Front plate XRN2-1
3.2.5 Front plate XRN2-2

TB XRN2 02.00 E 9
3.2.6 Parameter settings
Setting
parameter
XRN2-1 XRN2-2
∆/Y XX
U< X X
tU< XX
U<< X X
tU<< XX
U> X X
tU> XX
U>> X X
tU>> XX
fNXX
TXX
f1XX
tf1 XX
f2XX
tf2 XX
f3XX
tf3 XX
df X
dt X
1/3 X
∆Θ X
UB<XX
RS485/
Slave
XX
Table 3.2: Sequence of parameter setting of the two relay types

10 TB XRN2 02.00 E
4Working principle
4.1 Analog circuits
The input voltages are galvanically insulated by the in-
put transformers. The noise signals caused by inductive
and capacitive coupling are supressed by an analog R-
C filter circuit.
The analog voltage signals are fed to the A/D-
converter of the microprocessor and transformed to
digital signals through Sample- and Hold- circuits. The
analog signals are sampled with a sampling frequency
of 16 x fN, namely, a sampling rate of 1.25 ms for
every measuring quantity, at 50 Hz.
4.2 Digital circuits
The essential part of the XRN2 relay is a powerful mi-
crocontroller. All of the operations, from the analog
digital conversion to the relay trip decision, are carried
out by the microcontroller digitally. The relay program
is located in an EPROM (Electrically-Programmable-
Read-Only-Memory). With this program the CPU of the
microcontroller calculates the three phase voltage in
order to detect a possible fault situation in the protected
object.
For the calculation of the voltage value an efficient digi-
tal filter based on the Fourier Transformation (DFFT -
Discrete Fast Fourier Transformation) is applied to sup-
press high frequency harmonics and d.c. components
caused by fault-induced transients or other system dis-
turbances. The microprocessor continuously compares
the measured values with the preset thresholds stored in
the parameter memory (EEPROM). If a fault occures an
alarm is given and after the set tripping delay has
elapsed, the corresponding trip relay is activated.
The relay setting values for all parameters are stored in
a parameter memory (EEPROM - Electrically Erasable
Programmable Read Only Memory), so that the actual
relay settings cannot be lost, even if the power supply
is interrupted.
The microprocessor is supervised by a built-in "watch-
dog" timer. In case of a failure the watchdog timer re-
sets the microprocessor and gives an alarm signal via
the output relay "self supervision".
4.3 Voltage supervision
The voltage element of XRN2 has the application in
protection of generators, consumers and other electrical
equipment against over/and undervoltage.
The relay is equipped with a two step independent
three-phase overvoltage (U>, U>>) and undervoltage
(U<, U<<) function with completely separate time and
voltage settings.
In delta connection the phase-to-phase voltages and in
star connection the phase-to-neutral voltages are con-
tinuously compared with the preset thresholds.
For the overvoltage supervision the highest, for the un-
dervoltage supervision of the lowest voltage of the three
phases are decisive for energizing.

TB XRN2 02.00 E 11
4.3.1 Selection of star or delta connection
All connections of the input voltage transformers are led
to screw terminals. The nominal voltage of the device is
equal to the nominal voltage of the input transformers.
Dependent on the application the input transformers
can be connected in either delta or star. The connec-
tion for the phase-to-phase voltage is the delta connec-
tion. In star connection the measuring voltage is re-
duced by 1/ 3. During parameter setting the connec-
tion configuration either Y or ∆has to be adjusted.
Fig. 4.1: Input v.t.s in delta connection ( ∆ )
Fig. 4.2: Input v.t.s in star connection (Y)
4.4 Principle of frequency supervision
The frequency element of XRN2 protects electrical
generators, consumers or electrical operating equip-
ment in general against over- or underfrequency.
The relay has independent three frequency elements
f1- f3with a free choice of parameters, with separate
adjustable pickup values and delay times.
The measuring principle of the frequency supervision is
based in general on the time measurement of complete
cycles, whereby a new measurement is started at each
voltage zero passage. The influence of harmonics on
the measuring result is thus minimized.
J
KJ 6
6
Fig. 4.3: Determination of cycle duration by means of zero
passages.
In order to avoid false tripping during occurence of in-
terference voltages and phase shifts the relay works
with an adjustable measuring repetition (see chapter
6.2.3)
Frequency tripping is sometimes not desired by low
measured voltages which for instance occur during al-
ternator acceleration. All frequency supervision func-
tions can be blocked with the aid of an adjustable
voltage threshold UBin case the measured voltage
value is below this value.
4.5 Measuring of frequency gradient
(XRN2-2)
Electrical generators running in parallel with the mains,
e.g. industrial internal power supply plants, should be
separated from the mains when failure in the intrasys-
tem occurs for the following reasons:
•It must be prevented that the electrical generators
are damaged when mains voltage recovering
asynchrone, e.g. after a short interruption.
•The industrial internal power supply must be main-
tained.

12 TB XRN2 02.00 E
A reliable criterion of detecting mains failure is the
measurement of the rate of change of frequency df/dt.
Precondition for this is a load flow via the mains cou-
pling point. At mains failure the load flow changing
then spontaneously leads to an increasing or decreas-
ing frequency. At active power deficit of the internal
power station a linear drop of the frequency occurs
and a linear increase occurs at power excess. Typical
frequency gradients during application of "mains de-
coupling" are in the range of 0.5 Hz/s up to over
2 Hz/s. The XRN2 detects the instantaneous frequency
gradient df/dt of each mains voltage period in an in-
terval of one half period each. Through multiple evalua-
tion of the frequency gradient in sequence the continu-
ity of the directional change (sign of the frequency
gradient) is determined. Because of this special measur-
ing procedure a high safety in tripping and thus a high
stabilty against transient processes, e.g. switching pro-
cedure are reached. The total switching off time at
mains failure is between 60 ms and 80 ms depending
on the setting.
4.6 Vector surge supervision (XRN2-1)
The vector surge supervision protects synchronous gen-
erators in mains parallel operation due to very fast de-
coupling in case of mains failure. Very dangerous are
mains auto reclosings for synchronous generators. The
mains voltage returning after 300 ms can hit the gen-
erator in asynchronous position. A very fast decoupling
is also necessary in case of long time mains failures.
Generally there are two different applications:
a) Only mains parallel operation no single opera-
tion:
In this application the vector surge supervi- sion
protects the generator by tripping the genera- tor
circuit breaker in case of mains failure.
b) Mains parallel operation and single operation:
For this application the vector surge supervision
trips the mains circuit breaker. Here it is insured
that the gen.-set is not blocked when it is required
as the emergency set.
A very fast decoupling in case of mains failures for syn-
chronous generators is known as very difficult. Voltage
supervision units cannot be used because the synchro-
nous alternator as well as the consumer impedance
support the decreasing voltage.
For this the mains voltage drops only after some
100 ms below the pickup threshold of voltage supervi-
sion relays and therefore a safe detection of mains auto
reclosings is not possible with this kind of relay.
Frequency relays are partial unsuitable because only a
highly loaded generator decreases its speed within
100 ms. Current relays detect a fault only when short-
circuit type currents exist, but cannot avoid their develop-
ment. Power relays are able to pickup within 200 ms, but
they cannot prevent power to rise to short-circuit values
too. Since power changes are also caused by sudden
loaded alternators, the use of power relays can be
problematic.
Whereas the XRN2-1 detects mains failures within
60 ms without the restrictions described above because
they are specially designed for applications where very
fast decoupling from the mains is required.
Adding the operating time of a circuit breaker or con-
tactor, the total disconnection time remains below
150 ms. Basic requirement for tripping of the genera-
tor/mains monitor is a change in load of more than 15
- 20% of the rated load. Slow changes of the system
frequency, for instance at regulating processes (adjust-
ment of speed regulator) do not cause the relay to trip.
Trippings can also be caused by short-circuits within the
grid, because a voltage vector surge higher than the
preset value can occur. The magnitude of the voltage
vector surge depends on the distance between the
short-circuit and the generator. This function is also of
advantage to the Power Utility Company because the
mains short-circuit capacity and consequently the en-
ergy feeding the short-circuit is limited.
To prevent a possible false tripping the vector surge
measuring can be blocked at a set low input voltage
(refer to 6.2.8). The undervoltage lockout acts faster
then the vector surge measurement.
Vector surge tripping is blocked by a phase loss so that
a VT fault (e.g. faulty VTs fuse) does not cause false
tripping.
When switching on the aux. voltage or measuring volt-
age , the vector surge supervision is blocked for 5 s (re-
fer to chapter 4.8).

TB XRN2 02.00 E 13
Note:
In order to avoid any adverse interference voltage ef-
fects, for instance from contactors or relays, which may
cause overfunctions, XRN2-1 should be connected
separately to the busbar.
4.6.1 Measuring principle of vector surge
supervision
When a synchronous generator is loaded, a rotor dis-
placment angle is build between the terminal voltage
(mains voltage U1) and the synchronous internal volt-
age (Up). Therefore a voltage is difference ∆U is built
between Up and U1 (Fig. 4.4).
~
∆
U = I jX@I
I
U2UMains
Z
Fig. 4.4: Equivalent circuit at synchronous generator in parallel
with the mains
Fig. 4.5: Voltage vectors at mains parallel operation
The rotor displacement angle ϑbetween stator and
rotor is depending of the mechanical moving torque
of the generator shaft. The mechanical shaft power is
balanced with the electrical feeded mains power, and
therefore the synchronous speed keeps constant
(Fig. 4.5).
~
∆
U' I' jX@I'
U2U'Mains
Z
Fig. 4.6: Equivalent circuit at mains failure
In case of mains failure or auto reclosing the generator
suddenly feeds a very high consumer load. The rotor
displacement angle is decreased repeatedly and the
voltage vector U1changes its direction (U1') (Fig. 4.6
and 4.7).
Fig. 4.7: Voltage vectors at mains failure

14 TB XRN2 03.99 E
Fig. 4.8: Voltage vector surge
As shown in the voltage/time diagram the instantane-
ous value of the voltage jumps to another value and the
phase position changes. This is named phase or vector
surge.
The XRN2-1 measures the cycle duration. A new
measuring is started at each voltage zero passage. The
measured cycle duration is internally compared with a
quartz stable reference time and from this the deviation
of the cycle duration of the voltage signal is ascer-
tained. In case of a vector surge as shown in fig. 4.8,
the zero passage occurs either earlier or later. The es-
tablished deviation of the cycle duration is in compli-
ance with the vector surge angle.
If the vector surge angle exceeds the set value, the re-
lay trips immediately.
Tripping of the vector surge is blocked in case of loss
of one or more phases of the measuring voltage.
Tripping logic for vector surge measurement:
The vector surge function of the XRN2-1 supervises vec-
tor surges in all three phases at the same time. Tripping
of the relay can be adjusted for an one phase vector
surge (more sensitive measurement). For this the pa-
rameter 1/3 has to be set to "1Ph". When the parame-
ter 1/3 is set to "3Ph", tripping of the vector surge ele-
ment occurs only if the vector surge angle exceeds the
set value in all three phases at the same time.

TB XRN2 02.00 E 15
Application hint
Although the vector surge relay guarantees very fast
and reliable detection of mains failures under nearly all
operational conditions of mains parallel running alterna-
tors, the following borderline cases have to be consid-
ered accordingly:
a) None or only insignificant change of power flow at
the utility connection point during mains failures.
This can occure during peak lopping operation or in
CHP stations (Combined Heat and Power) where the
power flow between power station and the public grid
may be very low. For detection of a vector surge at
parallel running alternators, the load change must be at
least 15 - 20% of the rated power. If the active load at
the utility connection point is regulated to a minimal
value and a high resistance mains failure occurs, then
there are no vector surge nor power and frequency
changes and the mains failure is not detected.
This can only happen if the public grid is disconnected
near the power station and so the alternators are not
additionally loaded by any consumers. At distant mains
failures the synchronous alternators are abruptly loaded
by remaining consumers which leads directly to a vec-
tor surge and so mains failure detection is guaranteed.
If such a situation occurs the following has to be taken
into account:
In case of an undetected mains failure, i.e. with the
mains coupling C.B. closed, the vector surge relay re-
acts upon the first load change causing a vector surge
and trips the mains C.B.
For detecting high resistance mains failures a minimum
current relay with an adjustable trip delay can be used.
A trip delay is needed to allow regulating actions
where the current may reach "zero" at the utility connec-
tion point. At high resistance mains failures, the mains
coupling C.B. is tripped by the minimum current relay
after the time delay.
To prevent asynchronous switching on, an automatic
reclosing of the public grid should be not possible dur-
ing this time delay.
A further measure could be, that the load regulation at
the utility connection point guarantees a minimum
power flow of 15 - 20% of rated power.
b) Short circuit type loading of the alternators at distant
mains failures
At any distant mains failure, the remaining consumers
cause sudden short circuit type loading of the power
station generators. The vector surge relay detects the
mains failure in about 60 ms and switches off the
mains coupling C.B. The total switch off time is about
100 - 150 ms. If the generators are provided with an
extremely fast short circuit protection e.g. able to detect
di/dt, the alternators might be switched off
unselectively by the generator C.B., which is not de-
sireable because the power supply for the station is
endangered and later on synchronized changeover to
the mains is only possible after manual reset of the
overcurrent protection.
To avoid such a situation, the alternator C.B.s must
have a delayed short circuit protection. The time delay
must be long enough so that mains decoupling by the
vector surge relay is guaranteed.

16 TB XRN2 02.00 E
4.7 Voltage threshold value for
frequency measuring
At low measuring voltages, e.g. during generator start-
up, frequency and vector surge or df/dt-measuring is
perhaps not desired.
By means of the adjustable voltage threshold value
UB<, functions f1- f3, df/dt or ∆Θ are blocked if the
measured voltage falls below the set value.
4.8 Blocking function
No. Dynamic Behaviour U</<< U>/>> f1, f2, f3∆Θ df/dt
1 voltage to external
blocking input is
applied
free program-
mable
free program-
mable
free program-
mable
free program-
mable
free program-
mable
2 blocking input is
released
released
instantaneously
released
instantaneously
released after
1 s
released after
5 s
released after
5 s
3 supply voltage is
switched on
blocked for
200 ms
blocked for
200 ms
blocked for 1 s blocked for 1 s blocked for 1 s
4 3ph measuring volt.
is suddenly applied
released released blocked for 1 s blocked for 5 s blocked for 5 s
5 one or several
measuring voltages
are switched off
suddenly (phase
failure)
released released blocked blocked blocked
6measuringvoltage
smaller UB< (adjust-
able voltage thresh-
old value)
released released blocked blocked blocked
Table 4.1: Dynamic behaviour of XRN2 functions
Blocking function set in compliance with require-
ments :
The XRN2 has an external blocking input. By applying
the auxiliary voltage to input C1/C1L or C1/C1H, the
requested protection functions of the relay are blocked
(refer to 6.2.10).

TB XRN2 02.00 E 17
5Operation and setting
For adjustment of the unit the transparent cover has to
be opened as illustrated. Do not use force! The trans-
parent cover has two inserts for labels.
Fig. 5.1: How to open the transparent cover
5.1 Push buttons
Push buttons are used for calling up the parameters to
be processed, for selection of measuring parameters to
be indicated and for changing and storing the parame-
ters.
The individual setting and measuring values can be se-
lected one after another by pressing push button
<SELECT/RESET>. This push button is also used for re-
setting the display by pressing approx. 3s.
Push buttons <+> <-> are used for in-/decrementing of
the parameter indicated on the display. They can be
pressed step-by-step or continuously.
After the selected parameter is set by the <+> <-> push
button it may be stored using the <ENTER> push but-
ton.
Through the push button <ENTER> the set value indi-
cated on the display will be transfered to the internal
parameter memory. An unintented or unauthorized
change of the selected parameter is avoided by means
of a password identification (see 5.4.2).
The <TRIP>-push button is used to test the output relay
circuits both for tripping and signalling. During normal
operation it is also interlocked by means of the pass-
word identification.

18 TB XRN2 02.00 E
5.1.1 Indication of measuring values and
fault data
Indication in faultless condition
In normal operation the display always shows |SEG.
After pressing the push button <SELECT/RESET> the
display switches cyclically to the next measuring value.
After the measuring values had been indicated the set-
ting parameters are displayed. Hereby the LEDs in the
upper section signalize which measured value is indi-
cated, the LEDs in the lower section signalize which set-
ting parameter is indicated on the display. Longer ac-
tuating the push button resets the relay and the display
changes into normal operation (|SEG).
Indication after pickup / tripping
All of the faults detected by the relay are indicated on
the front plate optically. Here not only the faults are in-
dicated but also the faulty phase(s) and the protection
function in operation. During the excitation phase LEDs
are flashing, after tripping this changes to continuous
light.
In tripped condition "TRIP" appears on the display and
the LEDs of the operating measuring data light up red
together with the LEDs of the tripping parameter. All
operating data, which were measured at the moment
of tripping, can now be called one after another by
pressing push button <SELECT/RESET>. If in this condi-
tion setting parameters are to be indicated, push button
<ENTER> has to be pressed.
The graphic below shows again the difference be-
tween the different display modes.
<SELECT>
<SELECT>
<SELECT>
<ENTER>
|SEG TRIP
<SELECT>
<SELECT>
<ENTER>
<SELECT>
Display after tripping
Display in normal operation
Tripping
<RESET>
Measuring data
Parameter Parameter Failure data
Fig. 5.2: Switching over of the display in dependence of the operating mode.

TB XRN2 02.00 E 19
5.2 DIP switches
On the front plate of the XRN2-relay there is one DIP
switch to preset the following functions:
•Password programming
•Output relay functions
The figure 3.1 shows the position and designation of
the code jumpers:
5.2.1 Function of the output relays
The following functions of the output relays can be pre-
set:
•Alarm relay activation at pickup or after tripping
of the relay
•Reset of the output relays manually or automatically
The alarm relays are activated according to the preset-
ting:
Dip switch 2 OFF:
The alarm relays pickup directly with energizing of the
corresponding measuring circuit. Thus, an alarm signal-
ling can be given before the relay trips.
Dip switch 2 ON:
The alarm relays pickup only after relay trip. That
means: the trip relay and the corresponding alarm re-
lay pickup at the same time after the time delay
elapsed.
Dip switch 3 OFF:
All output relays will be reset automatically after the
fault has been rectified, (e.g. when the fault current is
interrupted).
Dip switch 3 ON:
All output relays remains activated and must be reset af-
ter fault clearence.
•Manually: By pressing push button
<SELECT/RESET>
•External: By connecting aux. voltage to C2/C2L or
C2/C2H
•Via RS 485 interface
To let the parameter change take effect, the auxiliary
voltage has to be switched on and off again after the
dip switches are plugged or unplugged.
Dip switch Function Dip switch
position
Operation mode
1Password OFF Normal position
ON Password selection
2Alarm relays OFF Alarm relays will be activated at pickup
ON Alarm relay will be activated at tripping
3Reset OFF Output relays will be reset automatically
ON Output relays will be reset manual/external/via software
4none
Table 5.1: Summary of coding possibilities

20 TB XRN2 02.00 E
5.3 Reset
Manual reset
By pressing push button <RESET/SELECT> for some
time (about 3 s).
External reset-input C2/C2L or C2/C2H
The external reset input has the same function as the
<SELECT/RESET> push button on the front plate. Con-
necting auxiliary voltage to this input, the unit can be
reset, provided that the fault is removed.
Software reset via serial interface RS 485
Software reset has the same function as push button
<SELECT/RESET>. Please refer to open data protocol
of RS 485 interface named RS485-PRO.
5.4 Password
5.4.1 Password programming
The XRN2-relay is delivered with the preset password
"++++", it can be programmed new with dip switch 1:
Apply dip switch 1. After power on and pressing any
push button, the relay XRN2 inquires for a new pass-
word. The text "PSW?" appears on the display. The
new password is entered by any combination of the
push buttons <SELECT> <-> <+> <ENTER>. After the
new password is given, the dip switch 1 has to be re-
moved.
5.4.2 Using the password
Step by step, a new relay setting is made according to
the following sequence:
•After the present setting value is changed with
<+><-> push button, <ENTER>-push button should
be pressed.
•A message "SAV?" appears on the display to inquire
if the new setting value is really wanted to be stored.
•After pressing the <ENTER>-push button again,the
password will be inquired by means of the message
"PSW?" on the display.
•After the password is given correctly, which is promp-
ted by message "SAV!" on the display, the new set-
ting value can be stored by pressing the<ENTER>-
push button for about 3 seconds.
•The new setting value for the selected parameter ap-
pears on the display again.
A password consists of four push button operations. The
pressed push buttons and their sequences define the
password.
<SELECT> = S
<-> = -
<+> = +
<ENTER> = E
then a password "-E+S" means pressing push buttons
according to the follwing sequence:
<-> <ENTER> <+> <SELECT>
After the password is given correctly, parameter setting
is permitted for five minutes. This means: For a subse-
quent parameter setting, as long as it is made within
five minutes after the password input, a renewed pass-
word input is not required. Moreover, the valid period
for parameter setting is automatically extended to fur-
ther 5 minutes after each new push button operation.
If no push button operation follows within the five min-
ute period after password input, the validity for pa-
rameter setting will be suspended.
For entering further parameters the password is then
called up again. During the validity for parameter set-
ting a new set value, after having acknowledged "SAV"
two times, is stored by just pressing push button
<ENTER> for some time.
As to parameter setting via RS 485 interface: see open
data protocol.