Suparule Sensorform CFZ User manual

v1.0
Sensorform CFZ Earth Fault Indicator User Manual

Suparule Systems Ltd Page 2 of 24 CFZ DCF2038 v1.09
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EFI

Suparule Systems Ltd Page 3 of 24 CFZ DCF2038 v1.09
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CONTENTS
SAFETY NOTICE......................................................................... 4
1OVERVIEW........................................................................... 6
2DESCRIPTION...................................................................... 7
2.1 C ONTROL U NIT .................................................................. 7
2.2 CT S ENSOR ...................................................................... 8
2.2.1 CT Sensor Selection................................................. 9
2.3 P OWER CT ..................................................................... 11
2.4 R EMOTE R ESET (O PTIONAL )............................................. 11
2.5 A UX . R ELAY (O PTIONAL ) .................................................. 11
2.6 M ANUAL T EST /R ESET B UTTON ......................................... 12
3USER-SELECTABLE TRIP OPTION (-S) .......................... 13
4OPERATION....................................................................... 14
4.1 E ARTH F AULT D ETECTION ................................................ 14
4.2 T RIPPED S TATE R ESETTING ............................................. 14
5TESTING ............................................................................ 16
6CONNECTION TERMINAL RATINGS ............................... 17
7SPECIFICATIONS .............................................................. 18
7.1 T ECHNICAL D ATA ............................................................. 18
7.2 M ECHANICAL D ATA .......................................................... 19
8ORDERING......................................................................... 20
9WARRANTY ....................................................................... 21

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Safety Notice
Review the following safety precautions to avoid injury and prevent damage to this
product or any products connected to it.
To avoid potential hazard, use this product only as specified. Electrical shock can cause
serious or fatal injury.
This unit may also be connected to other equipment that may have high voltages.
Improper use can cause serious or fatal injury.
PRECAUTIONS
Equipment is protected throughout by the use of double/reinforced
insulation as per IEC 60417-5172.
WARNING: Under certain fault conditions, high voltages can be brought
into the earth fault indicator enclosure. All parts within the enclosure
should be handled as if carrying dangerous voltages.
WARNING: Use extreme caution during the installation and use of the
Sensorform EFI product as high voltages and currents may be present in
the circuit.
WARNING: Observe precautions for handling Electrostatic Sensitive
Devices
•Ensure that the CT sensor is installed on the screened part of the HV cable
system and is at earth potential.
•This product must be installed and used only by qualified personnel that are
familiar with practicing applicable safety precautions.
•The Sensorform EFI product should not be installed on live conductors.
•Wear necessary protective clothing and gloves as required.
•Always inspect the EFI, CT sensor, and all leads for damage before using the
product. Do not use the product if damaged.
•If the Sensorform EFI is not used in a manner specified, the protection
afforded by the equipment may be impaired.

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•Static Electricity can damage sensitive electronic parts inside the unit. Any
accumulated charge on the body of the human operator should be discharged
first before removing the cover. The discharge can be accomplished by putting
a hand on a grounded surface or, ideally, by wearing a grounded antistatic
wrist-strap.
•The use of an antistatic strap prior to removing the cover is highly
recommended.
•Education and training on ESD preventive measures is recommended.
Cleaning
The Sensorform EFI unit is essentially a maintenance-free product. If the unit requires
cleaning, it should first be disconnected from all hazardous voltage sources. The unit
enclosure can then be wiped clean with a moist cloth. Ensure the unit is completely dry
prior to reconnection.

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1 Overview
The Sensorform EFI-CFZ is one of a family of Earth Fault Indicator products
that are designed to assist in the rapid location and isolation of faults on
Medium Voltage underground cable networks (1-38kV) in single-sided feed or
open ring main systems. When an asymmetrical current greater than the set
threshold level in a 3-phase cable is detected, an earth fault is indicated by
means of a Mechanical Flag indicator.
Sensorform EFI-CFZ is powered using a split-core current transformer (CT)
power supply that draws power from the load current flowing in one of the
phases being monitored.
The Sensorform EFI-CFZ has a current sensor fixed around the three phases
of the cable system that detects a current imbalance due to an earth fault. An
earth fault trip is indicated by a Mechanical Flag Indicator fitted in the unit, with
an (optional) Remote Reset input and an (optional) Auxiliary Relay Contact for
connection to other systems. In an open-ring network the path of the fault
current from the feeding point to the fault location is marked by the triggered
EFI’s. The defective conductor segment is located between the last EFI that
has been triggered and the first EFI which is still inactive.
The main features of the Sensorform EFI-CFZ model include:
•Powered by Current Transformer (Power CT) fixed around one phase
•Mechanical Flag indicator
•Automatic reset of fault on return of power
•Manual reset of fault by Test/Reset button on the front panel
•Manual reset of fault by remote Reset input (optional)
•CT100 Current Sensor (standard)
•CT150 Current Sensor (optional)
•CT300 Current Sensor (optional)
•Auxiliary Relay contact for remote alarm generation (optional)
•IP65-rated, flush-mount enclosure

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2 Description
The Sensorform EFI-CFZ consists of the following components:
2.1 Control Unit
This contains the necessary monitoring and detection circuits for detecting and
validating an earth fault as well as activating the fault indicator.
The control unit is normally mounted onto a vertical surface. When the cover is
removed, mounting screw holes are exposed for use in fixing the indicating unit
to a surface. Four two-way screw terminals inside the unit provide a means of
connecting the Power CT, Remote Reset, Aux. Relay and CT Sensor to the
unit. These cables are fed through the cable glands (M12) provided and
secured in place using the locking nut. When the cover and cable glands are
tightened firmly the enclosure provides IP65 protection.
Figure 1.0 Sensorform EFI-CFZ Control Unit
Backup Power
Supply
Remote Reset
Connector
CT
Connector
Mounting Screw
holes
Power CT
Connector Aux Relay
Connector
Cable Glands
Test/Reset Button
Trip Level
DIP Switch
Mechanical
Flag

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During the monitoring period the device is powered from a split-core current
transformer power supply that draws power from one of the phases being
monitored. The primary indication is a Mechanical Flag, which is normally
black, and flips to a red colour when a fault is detected.
When the external power source (current flowing in the phase where the Power
CT is attached) is first applied or when it returns after the fault is cleared, the
unit will first require up to 40 minutes (where the phase current is minimum
50A) to charge the on-board backup power supply before it can function
properly. This backup power supply is used to retain power to the unit on fault
detection for a typical period of 10 hours for the purpose of driving the
mechanical flag indicator and Aux. Relay, if fitted.
The standard unit is factory programmed to trip at a nominal earth fault current
of 50A (other trip values can be supplied on request). Units with -S in the
model number have user-selectable trip levels, from 3 or 4 factory-set levels.
The EFI will reset automatically from a fault state on detecting the presence of
the external power supply for more than 10 seconds continuous. It can also be
reset manually, prior to the external supply being restored. (See section 3.6).
The unit is designed to operate in the harsh environment of medium voltage
networks (1 - 38kV).
2.2 CT Sensor
The Sensorform CT sensor comprises of a flexible iron-core belt with a
magnetic field pickup coil attached. The belt is fitted around the three-phase
cable system being monitored and works on the principle of core-balance
current sensing. Under normal operating conditions the magnetic flux produced
by the three phase currents sums to zero resulting in the pickup coil on the
iron-core generating no voltage output. When an earth fault occurs the flux will
be non-zero resulting in a voltage proportional to the magnitude of the earth
fault being generated by the pickup coil. The CT sensor has no exposed iron
parts and is completely encapsulated in corrosion proof material. The CT is
supplied with a 3-meter length of cable as standard.

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2.2.1 CT Sensor Selection
The Sensorform EFI-CFZ comes with the CT100 sensor connected as
standard. A CT150 sensor is also available but must be specified at order.
Both CT’s are suitable for multi-core cable systems. A larger sensor CT300 is
available for single-core cable systems and must be specified at order.
2.2.1.1 Multi-Core Cable System
For multi-core cable systems the CT100 (or CT150) sensor is mounted on the
screened part of the cable, below the strip-back point of the cable as shown in
Figure 2.0. The inner cable-tie of the CT sensor is used to secure the sensor
firmly on the cable. The flexible iron core of the sensor must be wrapped in a
closed circle and pulled tight with the second, outer cable-tie, as far as is
possible.
Care should be taken to ensure that the sensor is mounted on the screened
part of the cable. The screen of the cable should be turned back underneath
the core and terminated to earth as shown in Figure 2.0. The third cable tie (if
fitted) must be closed, to ensure the end of the CT is properly aligned. The
end of the bands should be fitted neatly under itself. Care must be taken during
this process, to ensure the CT is closed properly. Otherwise the accuracy of
the trip level will be affected .
Figure 2.0 Mounting of CT100/CT150 Sensor on Multi-Core Cable System

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2.2.1.2 Single-Core Cable System
For Single-core cable systems a larger CT300 sensor is used. The CT300
sensor is mounted on the screened part of the cable below the strip-back point
of the cable as shown on Figure 2.1. The centre cable-tie of the CT is first used
to secure the sensor on one of the cables. The flexible iron core of the sensor
is then wrapped in a closed circle around all three cables and pulled tightly with
the second cable-tie as far as is possible.
Care should be taken to ensure that the sensor is mounted on the screened
part of the cable. The screen of all three conductors should be turned back
underneath the core and terminated to earth as shown in Figure 2.1. Care must
be taken during this process, to ensure the CT is closed properly. Otherwise
the accuracy of the trip level will be affected. The mini cable-ties are used to
ensure the end of the CT is properly aligned. The ends of the band should
overlap each other fully. The white line marks at each end must be aligned and
the two mini cable-ties securely tightened.
Note: For accurate detection of the trip current it is important that the CT
sensor is correctly and securely fitted to the cable system.
Figure 2.1 Mounting of CT300 Sensor on Single-Core Cable System

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2.3 Power CT
The Power CT on the CFZ units provides power to the internal backup supply,
by magnetically inducing current from the current flowing in one of the phase
conductors.
The Power CT is fixed around the phase conductor, as shown in Figures 2.1
and 2.1 above, and held in place by the inner cable-tie, which should be
tightened as far as possible. The outer cable-tie should then be tightened, such
that the ends of the coil band overlap.
2.4 Remote Reset (Optional)
The EFI-CFZ model with the suffix -T in the model number has the facility for
remote reset. An external (voltage-free) switch or relay contact can be
connected to the Remote Reset input connector. This is a normally open input.
If the unit is in fault model, when this input is closed (by means of an external
momentary switch or relay contact) for a miniumum period of 3 seconds, the
unit will reset.
A two-way screw terminal connector is provided on-board to connect to the
remote reset input.
2.5 Aux. Relay (Optional)
Additional signalling can be provided by an on-board latching relay, if specified
at time of order. The Aux. Relay provides potential-free, normally-open
contacts for healthy-state monitoring.
The Aux Relay contacts are normally open. A tripped state will latch the relay
into a set position (closed). The latching relay retains its last set state even
after the power supply is removed from the unit. The Aux. Relay is supplied
with a 2-meter length of cable as standard.
NOTE: When the external power supply (Power CT) is first applied to the unit
or when it returns after a cleared fault condition, the unit may require up to 40
minutes (where the Power CT is attached to a phase cable carrying minimum

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50A) to charge the on-board backup power supply, after which it resets the
latching relay into the reset position.
NOTE: Care must be taken not to exceed the maximum switching capacity of
the Aux Relay as indicated in Auxiliary Relay Specification in section 6 below. If
necessary, this connection should be fuse-protected.
2.6 Manual Test/Reset Button
The control unit includes a manual Test/Reset button on the front panel that
can be used to test the operation of the unit. This button is used to both test the
system and also to manually reset an earth fault state prior to the external
power supply being restored. The unit can only be manually tested if the unit
has first been charged by the external Power CT for up to 40 minutes when the
Power CT is attached to a conductor carrying minimum 50A.
To test the system the Test/Reset button must be pressed for a period of 3
seconds (this period is necessary to avoid accidental operation). This will
activate the Aux. Relay contacts (closed), if fitted, and the Mechanical Flag
indicator will be activated (switch to Red colour). This test state will continue for
a period of 60 seconds or until the test button is pressed again to terminate test
mode.
To manually terminate a test, the Test/Reset button is pressed again. This will
reset the Aux. Relay to the reset (opened) position and reset the mechanical
flag to the off (black) state.

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3 User-selectable Trip Option (-S)
EFI units with -S in the model number have an in-built user-selectable fault trip
level. This feature allows the user to select one of 3 or 4 different factory-set
trip levels, depending on the model. Nominal values should be specified and
agreed at order.
The user can select one of three or four different settings, Trip 1, Trip 2, Trip 3
and Trip 4 which can represent for example 25A, 50A, 80, and 120A. The
actual trip levels to which each of these settings relates is shown on a label on
the side of the unit.
To change the trip level, carry out the following:
1. Remove the top cover by unscrewing the four fixing screws.
2. Locate the Trip Level DIP switch as per Fig. 1 above.
3. Select the trip setting by sliding the switch corresponding to the
required trip level to ON. Ensure all others are OFF.
4. Replace the top cover, ensuring that the lid seal is positioned
correctly in the groove in the lid.
Switch ON position

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4 Operation
During normal monitoring operation the device is continuously powered from
the external Power CT supply. When power is first applied to the unit or when it
returns after a cleared fault condition, it is important to note that the unit will
first require up 40 minutes (where the Power CT is attached to a phase cable
carrying minimum 50A) to charge the on-board backup power supply before it
can function properly. This backup power supply is used to power the unit on
fault detection for a nominal period of 10 hours, driving the mechanical flag
indicator, and aux. relay, if fitted.
4.1 Earth Fault Detection
The Sensorform EFI-CFZ control unit continuously monitors the output signal
from the CT sensor as well as the Test/Reset button and Remote Rest input (if
fitted). In the event of an earth fault occurring, the CT sensor will generate a
voltage that is proportional to the measured current. The on-board circuitry
analyses the voltage produced to determine that it is a valid earth fault signal
as opposed to a transient spike or glitch. The minimum fault duration is 2.5
cycles (50mSec for 50Hz or 40mSec for 60Hz). All current spikes and glitches
are ignored. For fault currents in excess of the set trip current, a limiting circuit
inside the control unit clamps the output voltage of the CT sensor to a safe
operating voltage for the unit.
When a valid fault current is detected, the Aux. Relay will be latched into a
tripped (closed) position and the mechanical flag indicator will be activated, i.e.
switch to the RED color.
The unit will remain in a tripped state until automatically reset by the restoration
of the external power supply for minimum 10 seconds continuous, or manually
reset by pressing the Test/Reset button for more than 3 seconds, or by the
Remote Reset input closing for a minimum of 3 seconds.
4.2 Tripped State Resetting
Depending on the model type, resetting of a tripped state can be done
manually or automatically.

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Automatic Reset
On return of network power (minimum 10A flowing in the phase conductor to
which the Power CT is attached) the unit will validate the presence of power for
a continuous period of 10 seconds, following which the device will
automatically clear the tripped state. This will latch the Aux. Relay to a reset
position (open) and reset the Mechanical Flag indicator to the OFF (Black)
state.
NOTE: In the event of the internal backup power supply being fully discharged,
the minimum charge-up time is needed, before the tripped state can be reset.
Manual Reset
The Test/Reset button can be used to manually reset the unit from a tripped
state. To do this the Test/Reset button must be pressed for a minimum period
of 3 seconds.
The Remote Reset input can also be used to manually reset the unit from a
tripped state. To do this, the input to the Remote Reset should be shorted
(closed) for a minimum of 3 seconds.

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5 Testing
To check the trip current level of the Sensorform EFI the following test should
be conducted:
1. Ensure that the external power CT is attached to a conductor carrying
minimum 50A for a period greater than 40 minutes.
2. Generate a fault current less than 90% of the set trip current in a
current carrying conductor running through the CT sensor. For
example, for a trip level of 50A, set the fault current to 45A. This should
not trip the unit.
3. Generate a fault current greater than 110% of the set trip current, (e.g.
55A for a trip level of 50A) for a period of minimum 1 second. This
should trip the unit.
4. Should a minimum of 10A be still flowing in the conductor to which the
Power CT is attached, the unit should reset after a period of 10
seconds.

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6 Connection Terminal Ratings
Connector
Typical Voltage
Typical Current
External Power
Supply (Input)
8Vac 15mA
Remote Reset
(Input)
No voltage to be
applied
0.5mA
Aux Relay 250VAC,
220VDC
Max Continuous
Current 2A
Maximum switching
Capacity 60W
CT (Input)
Trip Pulse
10V ac 100mA

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7 Specifications
7.1 Technical Data
Control Unit
Network voltage range: 1-38kV AC
External Power CT Current range: 10A to 600A phase current
Trip current Levels: As per label on side of unit (+/-10%)
Minimum fault duration: 2.5 cycles (50ms @ 50Hz / 40ms @ 60Hz)
Fault current withstand: 25kA for 1s
Power CT charging time: 40 minutes @ 50A
Operating temperature range: -20ºC to +70ºC
Operating humidity range: 0 - 100% RH
Ingress Protection: IP65
Altitude: 5000 meters
Primary Indication: Mechanical Flag
Reset of Fault: Automatic 10s after power return
or Manual via Test/Reset button
or Remote Reset Input
Auxiliary Relay (optional)
Type: Latching, N/O on reset
Max Switching Voltage: 250VAC, 220VDC
Max Continuous Current: 2A
Maximum switching Capacity: 60W
Maximum Surge Protection 700V
Lead length standard:
1
2m
Lead type: 2-core, 0.5mm sq double insulated
Remote Reset Input (optional)
Type: Potential-free, N/O on reset
Max current when closed: 0.5mA
Lead length standard:
1
2m
Lead type: 2-core, 0.5mm sq double insulated
1
Extra length cable can be obtained at extra cost, if requested at order.

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7.2 Mechanical Data
Control Unit
Dimensions: 115 × 65 × 40mm excl. cable glands
Material: PC grey
Mounting: Surface-mounting, two 4mm holes
Cable gland size: M12; cable diameter range 3-6.5mm
Weight: 200g
CT sensor
CT100 (Shipped as standard): To fit 40-100mm diameter (Multi-core
cables)
CT150 (Ordered separately): To fit 90-150mm diameter (Multi-core
cables)
CT300 (Ordered separately): 300mm x 100mm (Single-core cables)
Mounting: Releasable cable-ties
Lead length standard:
1
3m
Lead type: 2-core, 0.5mm sq., double insulated
Weight CT100: 145g

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8 Ordering
Sensorform Earth Fault Indicator ordering information
First Group Product Range EFI Earth Fault Indicator
Second Group 1
st
Char: Power Source
B
C
D
Battery Powered
CT Powered
DC Powered
M Mains Powered
2
nd
/3
rd
Char: Primary Indicator Type F Flag
L LED
3
rd
/4
th
Char: Enclosure Type Z IP65 Flush-mount
Third Group 1st Char: Remote Indicator option R Remote LED Indicator
2
nd
Char: Cable length in metres 3 3 meters
Fourth Group 1
st
Char: Aux. Relay option A Aux. Relay fitted
2
nd
Char: Cable length in metres 2
T
2 meters
Pulsed (500mS) output
Fifth Group 1
st
Char: Power cable fitted M/D/P Power cable
2
nd
Char: Cable length in metres 3 3 meters
Sixth Group 1
st
Char: Reset cable fitted T Reset cable
2
nd
Char: Cable length in metres 3 3 meters
Seventh Group Nominal trip current in Amps xx xx Amps trip level
User-selectable trip level S
3 nominal trip levels to
be specified at order,
e.g. 40-80-120A
Eight Group 1
st
Five Char: Current Sensor (CT) CT100 Up to 100 mm dia.
(multi-core cables)
CT150 Up to 150mm dia.
(multi-core cables)
CT300 300mm × 100mm
(single-core cables)
6&7
th
Char: Cable length in metres 3 3 meters
For example:
Notes:
• The Remote Indicator & Aux. Relay are optional components.
• The EFI unit does not ship with any leads for the power supply input or the Aux. Relay output,
unless stated at time of order.
• The unused cable-glands ship with a rubber stopper inserted to maintain sealing integrity.
EFI-CFZ-A2-P3-T3-S20.35.50-CT100.3