EASUN REYROLLE LIMITED MIB202 User guide

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OCTOBER 2003
APPLICATION AND COMMISSIONING
MANUAL FOR NUMERICAL BIASED
DIFFERENTIAL PROTECTION RELAY
TYPE - MIB202
EASUN REYROLLE LIMITED

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ISSUE NO : 1st Issue
DATE OF ISSUE : 01 - 10 - 2003
DEPARTMENT :AS

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CONTENTS
PAGE
APPLICATION 4 - 9
INSTALLATION 10 - 19
COMMISSIONING 20- 25
DRAWING 26

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APPLICATION
The MIB202 is micro-controller based Numerical Biased Differential
Protection Relay with inbuild Current Amplitude and Vector Group
Compensation features and also with Instantaneous Differential Highset
Element for two winding Power Transformer and AutoTransformers.
MIB202 relay, which can be used to operate for internal faults, like
phase to phase, phase to earth and inter turn faults in the
Transformers.
The same relay, we can use for 1A or 5A CT input on both LV & HV side.
The relay has supervisory components and self-monitoring features give
high confidence of serviceability.
1.0 BIASED DIFFERENTIAL PROTECTION:
The currents entering and leaving the transformer are measured, taking
in to the Power Transformer vector grouping and transformation ratio.
Software interposing current transformers can be applied to each set of
current inputs to correct for any magnitude and vector mismatch and to
remove zero sequence components where necessary. They are then
summed to form an operate signal which is applied to a three part
biased differential characteristic on a phase by phase basis.
The relay is provided with triple slope characteristics.
1. Initial Differential setting
2. Differential Bias slope
3. Differential Bias slope limit
1.1 INITIAL DIFFERENTIAL SETTING:
This is the value of current, expressed as a percentage of the chosen
current rating, at which the relay will operate with zero bias current. Its
setting would normally be the same as that for the differential bias slope
value.
Setting Range:
I - 10% to 50% of In in steps of 5%

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1.2 DIFFERENTIAL BIAS SLOPE:
Some unbalance current will appear in the differential circuit of the relay
for predictable reasons, e.g. due to the transformer tap position and to
CT errors. The current will increase with increasing load or through fault
current in the transformer so, to maintain stability, the biasing current
must increase proportionately. The bias slope expresses the current to
operate the relay as a percentage of the biasing (restraint) current. The
differential bias slope setting chosen must be greater than the
maximum predictable percentage unbalance.
Setting Range:
bS - 10% to 70% of In in steps of 5%
1.3 DIFFERENTIAL BIAS SLOPE LIMIT:
This setting defines the upper limit of the bias slope and is expressed in
multiples of nominal rated current. A setting value must be chosen
which will cover the maximum through fault current of the transformer.
This setting gives more stability during CT saturation for heavy through
fault.
Setting Range:
SL - 200% to 2000% of In in steps of 100%
2.0 DIFFERENTIAL INSTANTANEOUS HIGHSET OVER
CURRENT:
This is an unbiased, instantaneous element in the differential circuit with
a range of settings expressed as percentages of the nominal current
rating. If the feature is not required, the OFF setting should be selected.
If it is required, it must be set to a value in excess of any predictable
differential current, i.e. the differential current under maximum through
fault conditions with the transformer tap changer in its extreme position
and the differential current due to magnetizing inrush. The highset
should be set as low as possible but not less than the maximum three
phase through fault current and not less than the maximum
magnetizing current.
Setting Range:
H - OFF, 400% to 2500% of In in steps of 100%

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3.0 MAGNETIZING INRUSH RESTRAINT:
Second Harmonic quantities are calculated from the signal I1 - I2 to
provide an inhibit signal to prevent the protection operating for
magnetizing inrush conditions. Magnetizing inrush on any phase will
inhibit all three phases.
4.0 INTERPOSING CT MULTIPLIER (HV AND LV SIDE):
This range of settings enable the effective ratio of the HV & LV CT's to
be adjusted.
Setting Range:
Ah & Al - 0.50 to 2.50 in steps of 0.01
5.0 HV INTERPOSING CT CONNECTION:
An equivalent interposing CT connection can be selected from this range
of settings. The settings define the LV and HV winding configuration.
E.g. Yd, followed by the angular position of the LV phasor with respect
to the HV phasor. The angular position is described by the hour - hand
position on the twelve-hour clock face, e.g. Yd1 or Yd11. In each
setting, this is followed by the same angular relationship expressed in
degrees. The complete Yd1 setting will therefore read Yd1, -30°and
Yd11 will read Yd11, 30°.
Setting Range:
Vh - Yy0, Yy2, Yy4, Yy6, Yy8, Yy10, Yd1, Yd3, Yd5, Yd7,
Yd9, Yd11, Ydy0 and Ydy6
6.0 LV INTERPOSING CT CONNECTION:
As the HV connection but now applied to the LV CT's.
Setting Range:
VL - Yy0, Yy2, Yy4, Yy6, Yy8, Yy10, Yd1, Yd3, Yd5, Yd7,
Yd9, Yd11, Ydy0 and Ydy6

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7.0 TYPICAL RELAY SETTING CALCULATION
Power Transformer Details:
Voltage = 132 / 33KV
Rating = 60MVA
Tap Changer = +5% - 15%
Vector Group = Yd1
Current Transformer Details:
CT Ratio
For HV Side = 300/1
For LV Side = 1200/1
Calculation:
HV rated current = 60MVA / (132 * 1.732)
= 262.4A.
CT ratio for HV side is 300/1
LV rated current = 60MVA / (33* 1.732)
= 1049.76A
CT ratio for LV side is 1200/1
Mean tap value = [(+5) + (-15)] / 2 = -5%
HV current at –5% tap = (60MVA) / (1.732 * 132KV *0.95)
= 276.2A
HV Multiplier = 300 / 276.2 = 1.086 = 1.09
LV CT secondary current = 1049.7 / 1200
= 0.87475A
So the LV multiplier = 1200 / 1049.7 = 1.143
= 1.14
Initial Setting = 200mA (20%) or
2 times of maximum spill current
whichever is greater.
Bias setting = 20%
2 times of maximum tap change %
Bias Slope Limit = 4 times of full load current
HV ICT vector connection = Yd1, 30
LV ICT vector connection = Yy0, 0
HV ICT multiplier = 1.09
LV ICT multiplier = 1.14

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8.0 INTERPOSING CT SELECTION GUIDE
Power Transformer Vector
Group
HV
Interposing
CT Selection
LV
Interposing
CT Selection
Yy0, YNy0, Yyn0, YNyn0, Ydy0,
Yndy0, Ydyn0, YNdyn0
Yd1,30° Yd1,30°
Yd1, YNd1 Yd1,30° Yy0,0°
Yd1, YNd1 + Earthing Transformer Yd1,30° Ydy0,0°
Yy2, YNy2, Yyn2, YNyn2, Ydy2,
Yndy2, Ydyn2, YNdyn2
Yd3,90° Yd1,30°
Yd3, YNd3 Yd3,90° Yy0,0°
Yd3, YNd3 + Earthing Transformer Yd3,90° Ydy0,0°
Yy4, YNy4, Yyn4, YNyn4, Ydy4,
Yndy4, Ydyn4, YNdyn4
Yd5,150° Yd1,30°
Yd5, YNd5 Yd5,150° Yy0,0°
Yd5, YNd5 + Earthing Transformer Yd5,150° Ydy0,0°
Yy6, YNy6, Yyn6, YNyn6, Ydy6,
Yndy6, Ydyn6, YNdyn6
Yd7,-150° Yd1,30°
Yd7, YNd7 Yd7,-150° Yy0,0°
Yd7, YNd7 + Earthing Transformer Yd7,-150° Ydy0,0°
Yy8, YNy8, Yyn8, YNyn8, Ydy8,
Yndy8, Ydyn8, YNdyn8
Yd9,-90° Yd1,30°
Yd9, YNd9 Yd9,-90° Yy0,0°
Yd9, YNd9 + Earthing Transformer Yd9,-90° Ydy0,0°
Yy10, YNy10, Yyn10, YNyn10, Ydy10,
Yndy10, Ydyn10, YNdyn10
Yd11,-30° Yd1,30°

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Yd11, YNd11 Yd11,-30° Yy0,0°
Yd11, YNd11 + Earthing Transformer Yd11,-30° Ydy0,0°
Dy1, Dyn1 Ydy0,0° Yd11,-30°
Dy1, Dyn1 + Earthing Transformer Ydy0,0° Yd11,-30°
Dy3, Dyn3 Ydy0,0° Yd9,-90°
Dy3, Dyn3 + Earthing Transformer Ydy0,0° Yd9,-90°
Dy5, Dyn5 Ydy0,0° Yd7,-150°
Dy5, Dyn5 + Earthing Transformer Ydy0,0° Yd7,-150°
Dy7, Dyn7 Ydy0,0° Yd5,150°
Dy7, Dyn7 + Earthing Transformer Ydy0,0° Yd5,150°
Dy9, Dyn9 Ydy0,0° Yd3,90°
Dy9, Dyn9 + Earthing Transformer Ydy0,0° Yd3,90°
Dy11, Dyn11 Ydy0,0° Yd1,30°
Dy11, Dyn11 + Earthing Transformer Ydy0,0° Yd1,30°
Notes:
1. Y or y denotes an unearthed star connection on the HV or LV side
of the transformer respectively.
2. YN or yn denotes an earthed star connection on the HV or LV side
of the transformer respectively.
3. D or d denotes a delta connection on the HV or LV side of the
transformer respectively.

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INSTALLATION
1.1 UNPACKING
On receipt, remove the relay from the carton box in which it was
received and inspect it for obvious damage. It is recommended that the
relay is not removed from the relay case. To prevent the possible
ingress of dirt, the sealed polythene bag should not be opened until the
relay is to be used.
If damage has been sustained, please inform Easun Reyrolle Ltd.,
for necessary action.
1.2 STORAGE
When the relay is not required for immediate use, it should be
returned to its original carton and stored in a clean dry place.
1.3 HANDLING
The relay’s electronic circuits are protected from damage by static
discharge when the relay is housed in its case. When relay is withdrawn
from the case, static handling procedures should be observed:
•Before removing the relay from its case the operator must first
ensure that he is at the same potential as the relay, by touching
the case.
•The relay must not be handled by any of the relay terminals at the
rear of the chassis.
•Ensure that anyone else handling the relay is at the same potential.
As there are no user serviceable parts and adjustable user settings
inside the relay, there should be no requirement to remove any modules
from the chassis.
If any modules are removed or tampered with, then the guarantee
will be invalidated.
1.4 MOUNTING
Mount the relay using 2 nos. mounting straps and 1no earth strap.
Ensure that an earth wire is connected to the earth strap from the earth
terminal 23. Terminal 23 should be directly connected to the system
ground.
Only settings or trip details can be accessed via the pushbuttons
when the cover is fitted. To change the settings the front cover has to

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be removed. Sealing arrangement is provided in one of the four
knurling screws fitted on the cover. Sealing can be done using a sealing
wire. Thus mechanical interlock is provided to avoid unauthorized
setting change.
2.1 CURRENT TRANSFORMER TAP SELECTION
MIB202 relays are suitable for 1A or 5A application. However the
relays are internally wired for either 1A or 5A as per the customer
requirement. Internal wiring are to be changed (Faston crimp
connections) for changing the relay rating from one to other.
To ensure the current rating of the relay, check the connection of
CT wires connected to the bottom TB (Terminal Block) at the rear of the
chassis as per the following table:
For 1A
Phase Terminal
No. of TB
Ferrule No. of CT
Wire(Black)
A 1 1A
B 3 3A
HV Side
C 5 5A
A 7 7A
B 9 9A
LV Side
C11 11A
For 5A
Phase Terminal
No. of TB
Ferrule No. of CT
wire(Black)
A 1 1B
B 3 3B
HV Side
C 5 5B
A 7 7B
B 9 9B
LV Side
C11 11B
Following are the steps to change the current rating of the relay from 1A
to 5A.
1) Identify LV & HV side phases terminal from number strip on
bottom terminal block at the rear of the chassis.

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2) The black colour wire “9A” is inserted to 9th terminal of TB.
3) First, carefully lift the PVC boot of the wire by means of a tool
(like nose pliers) to expose terminal 9A.
4)Hold the crimp by means of the same tool at the crimp point and
lift to remove from the fixed terminal. Remove the “9B” wire from
the terminal parking rack (fixed on terminal block) and insert the
crimp of “9B” wire on to the terminal No.9 by means of the tool.
Insert "9A" wire back to the terminal parking rack.
5) Ensure proper insertion of “9B” wire by pulling the wire by hand
and the wire should not come off the terminal.
6) Push the boot of “9B” wire, to completely cover the crimp.
Same procedure in reverse is to be followed to change from 5A to
1A using appropriate wire numbers
2.2 HUMAN MACHINE INTERFACE (HMI)
The user friendly HMI provided on the front panel has following
features:
1. Six digit, 7 segment LED display (First two digits are Red colour
and other four digits are Green colour). First two digits (Red)
displays the main menu or type Element operated when
selected for Setting mode or Trip indication respectively.
Remaining four digits (Green) displays Sub menu or "Trip"
indication respectively.
2. Green LED - Protection healthy indication
3. Red LED (HIGHSET) - Highset trip indication
4. Red LED (TRIP) - Trip indication
5. Red LED (in Key) - Sub Menu
6. Key - Up scrolling
7. Key - Down scrolling
8. Key - Sub menu

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9. Key - Enter / Reset / Cancel / To check
Version
3.0 SETTING INSTRUCTIONS
3.1 How to operate HMI
♦Remove the front cover by unscrewing the four knurling screws.
♦Apply DC supply. Terminals 22,24 and 23 are for positive, negative
and earth respectively as per relay rating. When the relay powers up
it takes few seconds to complete the self-test routine.
♦Ensure Protection Healthy LED (Green) is ON and indication
appears on the LED display unit. Wait until the indication goes
off.
♦Press or key is displayed
Represents MIB 202 relay
♦Press key repeatedly scrolls down the Factory setting Main menu
in the following order on the display.
- Initial setting in % of nominal rating
- Bias slope setting in %
- Slope limit setting in % of Restraining current
(I1+I2)/2
- Current Amplitude correction setting for HV
windings
- Current Amplitude correction setting for LV
windings
- Vector group compensation setting for HV
windings

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- Vector group compensation setting for LV
windings
- Highset setting
3.2 DIFFERENTIAL INITIAL SETTINGS
Setting Range: 10% to 50% in steps of 5% (The setting refers to
% of rated nominal CT secondary rating)
Pressing key (represents initial setting is 20% of
rated nominal current) display will appear, press key
(Submenu LED On) to get the Sub menu. Pressing or key
changes the current setting in 5% increment or decrement. Upon
selecting the desired setting, once again press the key (Sub
menu LED goes OFF) to return to the main menu.
3.3 DIFFERENTIAL BIAS SLOPE SETTINGS
Setting Range: 10% to 70% in steps of 5% (Restraining
characteristics)
Pressing key (represents slope setting is 20%)
display will appear, press key (Submenu LED On) to get the
Sub menu. Pressing or key, change the bias characteristic
percentage setting 10% to 70%. Upon selecting the desired
setting, once again press the key (Sub menu LED goes OFF) to
return to the main menu.
3.4 DIFFERENTIAL BIAS SLOPE LIMIT SETTINGS
Setting range: 200% to 2000% of restraining current (I1+I2)/2 in
steps of 100%.
Pressing key repeatedly and get Main menu
(represents slope limit setting of the bias characteristics is 400%),
press key (Submenu LED On) to get the Sub menu. Pressing
or key changes the slope limit setting in 100% increment or
decrement. Upon selecting the desired setting, once again press
the key (Sub menu LED goes OFF) to return to the main menu.

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3.5 CURRENT AMPLITUDE CORRECTION SETTINGS
3.5.1 HV side ICT multiplier
Setting range: 0.50 to 2.50 in steps of 0.01.
Pressing key repeatedly and get Main menu
(represents current amplitude correction setting of HV winding
current input is 1.00), press key (Submenu LED On) to get the
Sub menu. Pressing or key changes the current amplitude
correction setting in 0.01 increment or decrement. Upon selecting
the desired setting, once again press the key (Sub menu LED
goes OFF) to return to the main menu.
3.5.2 LV side ICT multiplier
Setting range: 0.50 to 2.50 in steps of 0.01.
Pressing key repeatedly and get Main menu
(represents current amplitude correction setting of LV winding
current input is 1.00), press key (Submenu LED On) to get the
Sub menu. Pressing or key changes the current amplitude
correction setting in 0.01 increment or decrement. Upon selecting
the desired setting, once again press the key (Sub menu LED
goes OFF) to return to the main menu.
3.6 VECTOR GROUP COMPENSATION SETTINGS
3.6.1 Vector group compensation on HV windings
Settings available: Yy0, Yy2, Yy4, Yy6, Yy8, Yy10, Yd1, Yd3, Yd5,
Yd7, Yd9, Yd11, Ydy0 and Ydy6
Pressing key repeatedly and get Main menu
(represents Vector group compensation for HV winding is Yy0),
press key (Submenu LED On) to get the Sub menu. Pressing
or key changes the Vector group compensation setting
desired by increment or decrement. Upon selecting the desired
setting, once again press the key (Sub menu LED goes OFF)
to return to the main menu.

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3.6.2 Vector group compensation on LV windings
Setting available: Yy0, Yy2, Yy4, Yy6, Yy8, Yy10, Yd1, Yd3, Yd5,
Yd7, Yd9, Yd11, Ydy0 and Ydy6
Pressing key repeatedly and get Main menu
(represents Vector group compensation for LV winding is Yy0),
press key (Submenu LED On) to get the Sub menu. Pressing
or key changes the Vector group compensation setting
desired by increment or decrement. Upon selecting the desired
setting, once again press the key (Sub menu LED goes OFF)
to return to the main menu.
3.7 HIGHSET SETTING
Setting range: OFF, 400% to 2500% of nominal current in steps
of 100%.
Pressing key repeatedly get Main menu (represents
the highset element is OFF). Press key (Submenu LED On) to
get Submenu. Pressing or key, changes the highset setting
by 100% of rated current. After selecting the desired setting, once
again press the key (Sub menu LED goes OFF) to get back the
main menu.
4.0 ACCEPTANCE OF SETTINGS (ENTER)
For the relay to accept the above setting changes press key
once, now the display goes off and the settings are updated. By
pressing any key again indication will appear
Ensure all the chosen settings. In case of any changes required
use Sub menu key and then do the changes and finally press
enter key once.
ENSURE TO PRESS ‘ ’ TO ACCEPT THE CHANGES

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5.0 TO CHECK THE RELAY VERSION
Press key four times, example of relay version display is as
follows:
Represent MIB 202-relay version 1
To get back the main menus press or key.
6.0 TO CANCEL SETTING WHILE CHANGING (CANCEL)
While the particular setting is being changed (using or key)
with Submenu LED ON, by pressing key, the original setting is
restored
7.0 TRIP INDICATION AND RESETTING OF TRIP
INDICATION (RESET)
When the relay operates, "TRIP" LED indicates tripping. To find
which element operated press or key. There is possibility for
the following display after the trip,
- Indicates r – phase trip
- Indicates y – phase trip
- Indicates b – phase trip
- Indicates Highset element of r – phase trip
- Indicates Highset element of y – phase trip
- Indicates Highset element of b – phase trip
Once the fault is cleared, press key twice to reset the
trip indication.
The trip indication will be retained in Non - volatile memory during
auxiliary DC power supply failure.
8.0 METERING MODE FOR COMMISSIONING PURPOSE
The relay includes metering function also to enable the
commissioning people to verify their configuration and settings.

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To enter into this mode, the sub menu key has to be pressed
for around 10 secs. After the time delay the relay front LED will
display the following signals as in the order given below by
pressing the key.
- Indicates HV winding r – phase line current
- Indicates LV winding r – phase line current
- Indicates HV winding r – phase relay current
after amplitude and phase angle (Vector group
correction) correction.
- Indicates LV winding r – phase relay current
after amplitude and phase angle (Vector group
correction) correction.
- Indicates r – phase restraining current
- Indicates r – phase differential current
- Indicates HV winding y – phase line current
- Indicates LV winding y – phase line current
- Indicates HV winding y – phase relay current
after amplitude and phase angle (Vector group
correction) correction.
- Indicates LV winding y – phase relay current
after amplitude and phase angle (Vector group
correction) correction.
- Indicates y – phase restraining current
- Indicates y – phase differential current
- Indicates HV winding b – phase line current
- Indicates LV winding b – phase line current

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- Indicates HV winding b – phase relay current
after amplitude and phase angle (Vector group
correction) correction.
- Indicates LV winding b – phase relay current
after amplitude and phase angle (Vector group
correction) correction.
- Indicates b – phase restraining current
- Indicates b – phase differential current
In order to come back from the metering mode to main menu
(Protection setting), the same sub menu key has to be pressed for again
10 secs. This is true even the relay is tripped. After about 10 minutes,
I.e. power save mode (During which the relay seven segment LED
display goes off if none of the front keys are pressed) the relay will back
to the main menu (Protection) mode for any key press after the relay
went to power save mode.
Note: The above metering display values are refered to 1 Amps
only. If 5 Amp relay is used, the obtained value has to be multiplied by
a factor of 5 to read the input current value.

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COMMISSIONING
1. REQUIRED TEST EQUIPMENT'S
•500V insulation test sets.
•Variable secondary injection current source rated 10A or greater.
•Variable voltage source.
•Time interval meter.
•A DC supply with a nominal voltage within the working range of the
relays DC auxiliary supply ratings.
2. INSPECTION
Ensure that all connections are tight and in accordance with the
relay wiring diagram and the scheme diagram. Check if the relay
is correctly programmed and the relay is fully inserted into the
case.
3. APPLYING SETTINGS
The relay settings for the particular application should be applied
before any secondary testing is started.
4. PRECAUTIONS
Before testing commences, the equipment should be isolated from
the current transformers and the CT's to be short-circuited, in line
with the local site procedures. The tripping and alarm circuits
should also be isolated, where practical. Also, ensure that trip
links are removed.
Ensure that correct DC auxiliary voltage and polarity is applied.
See the relevant scheme diagrams for the relay connections.
5. TESTS
5.1 INSULATION
Connect together all relay C.T. terminals and measure the
insulation resistance between these terminals and all of the other
relay terminals connected together and to earth.
Connect together the terminals of the DC auxiliary supply (only
+ve and -ve) and measure the insulation resistance between