Cybertronix Sentinel EFI-MFZ-50 User manual

Sentinel™ EFI-MFZ-50
EARTH FAULT INDICATOR
USER’S MANUAL

CONTENTS
1. SAFETY NOTICE ............................................................................................................3
2. OVERVIEW .....................................................................................................................4
3. FEATURES......................................................................................................................4
4. INSTALLATION ...............................................................................................................4
4.1 CURRENT SENSOR..................................................................................................4
4.1.1 MULTI-CORE CABLE SYSTEM..........................................................................4
4.1.2 SINGLE-CORE CABLE SYSTEM........................................................................7
4.2 INDICATING UNIT.....................................................................................................7
4.3 REMOTE INDICATOR (OPTIONAL)..........................................................................8
5. OPERATION....................................................................................................................8
5.1 CURRENT SENSOR..................................................................................................8
5.2 INDICATING UNIT.....................................................................................................8
5.2.1 AUXILIARY RELAY (OPTIONAL)........................................................................9
5.2.2 REMOTE INDICATOR (OPTIONAL)...................................................................9
5.2.3 MANUAL TEST AND RESET..............................................................................9
6. TESTING.......................................................................................................................10
7. SPECIFICATIONS.........................................................................................................11
8. ORDERING ...................................................................................................................13
9. WARRANTY..................................................................................................................15

Sentinel™ EFI-MFZ-50 User’s Manual
Version 3.0 Page 3 of 15
1. SAFETY NOTICE
Review the following safety precautions to avoid serious injury or death and to prevent
damage to this product or any products connected to it. To avoid potential hazards, use
this product only as specified. This equipment contains high voltages. Electrical shock can
cause serious or fatal injury.
PRECAUTIONS
WARNING: Under certain fault conditions, high voltages can be conducted
into the earth fault indicator enclosure through the CT, remote indicator, or the
auxiliary relay cables. All parts within the enclosure should be handled as if carrying
dangerous voltages.
WARNING: Use extreme caution during the installation and use of the earth
fault indicator as high voltages and currents may be present in the circuit.
•Ensure that the current sensor is installed at earth potential on the HV cable
system.
•Ensure that the current sensor is installed on the screened part of the cable
system.
•Use caution during the installation and use of this product; high voltages and
currents may be present in the circuit.
•This product must be used only by qualified personnel practicing applicable
safety precautions.
•Wear protective clothing and gloves as required.
•Do not install this product on live conductors.
•Always de-energize circuit before installing the current sensor and indicating
unit.
•Always inspect the current sensor, indicating unit and all leads for damage
before using the product.
•Do not use the product if damaged.
!

Sentinel™ EFI-MFZ-50 User’s Manual
Version 3.0 Page 4 of 15
2. OVERVIEW
The Sentinel EFI-MFZ-50 is one of a family of Earth Fault Indicator (EFI) products that is
designed to assist in the rapid location and isolation of earth faults on high voltage cable
networks. The EFI can be used in radial networks or in openly operated ringed networks.
When an asymmetrical current greater than 50A in a 3-phase cable system is detected an
earth fault is indicated by means of a flashing LED (light emitting diode) indicator. 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 which has been
triggered and the first EFI which is still inactive.
3. FEATURES
• Mains powered
• Flag indication
• Auxiliary relay output contact
• Remote indication driver
• Split-core current sensor
• 50A nominal trip
• 50ms minimum fault duration
• Manual test and reset facility
• IP65 environment protection
• Rugged and reliable electronics
• ISO9001:2000 based quality assurance
• Electromagnetic compatibility
4. INSTALLATION
4.1 CURRENT SENSOR
The Sentinel current sensor consists of a flexible steel core which is wrapped around the
three-phase system to be monitored and fastened tightly in place with adjustable cable-
ties. The current sensor is normally shipped fastened in a closed position. The cable-ties
are released by depressing the small ratchet on the head while bending back the tail. The
current sensor and associated leads must be installed at earth potential on the screened
part of the cable and not go anywhere near the unscreened HV system. Also the current
sensor should not encircle the cable earthing. This can easily be achieved by looping the
earthing lead back down through the current sensor so as to bypass current sensor.
The current sensor is available in three different sizes depending on whether it is to be
applied to an installation consisting of a multi-core cable or a system comprising of three
single-core cables.
4.1.1 MULTI-CORE CABLE SYSTEM
The Sentinel EFI ships with a standard sized (CT100) current sensor, which is suitable for
most multi-core cable systems. A larger current sensor (CT150) is also available but must

Sentinel™ EFI-MFZ-50 User’s Manual
Version 3.0 Page 5 of 15
be specified at time of order. The flexible sensor core is mounted on the screened part of
the cable, below the stripback point. The core is wrapped around the cable and the cable-
tie is pulled tight as far as it will go. A second cable-tie is used to hold the core firmly onto
the cable. The cable screen is turned back underneath the core and then terminated to
earth as shown in the Figure 1.

Sentinel™ EFI-MFZ-50 User’s Manual
Version 3.0 Page 6 of 15
EARTH
CURRENT
SENSOR
FIGURE 1: CURRENT SENSOR MOUNTED ON MULTI-CORE CABLE SYSTEM
OUTGOING CABLE
TERMINATION
CURRENT
SENSOR
L1 L2 L3
EQUIVALENT CIRCUIT
SCREEN
CURRENT
SENSOR
(
CT300
)
EARTH
FIGURE 2: CURRENT SENSOR MOUNTED ON SINGLE-CORE CABLE SYSTEM
OUTGOING CABLE
TERMINATION
CURRENT
SENSOR
L1 L2 L3
EQUIVALENT CIRCUIT
SCREEN

Sentinel™ EFI-MFZ-50 User’s Manual
Version 3.0 Page 7 of 15
4.1.2 SINGLE-CORE CABLE SYSTEM
A larger current sensor (CT300) is available for application on single core cable systems.
These systems usually consist of three single-core cables spaced in a row, side-by-side.
The flexible sensor core is wrapped tightly around all three cables forming a rectangular
oval, and fastened in place with cable-ties. Care should be taken to ensure that the core is
mounted on the screened part of the cable. The screen of all three conductors should be
turned back underneath the core and then terminated to earth as shown in Figure 2.
4.2 INDICATING UNIT
The Sentinel indicating unit is normally flush mounted onto a vertical surface. When the
cover is removed, mounting holes are exposed for use in bolting the indicating unit to a
surface. The current sensor and other accessories are electrically connected to the
indicating unit by feeding the leads through cable glands (PG7) on the indicating unit and
connecting them to two-way screw terminals mounted inside the indicating unit enclosure.
With the cover and cable glands tightened firmly the enclosure provides IP65 protection.
Backup Power Supply
Mounting
Holes
Mains
Supply
Terminal
Remote
Indicator
Terminal
Auxiliary
Relay
Terminal
CT Terminal
Cable Glands
Test/Reset
Pushbutton
Enclosure Lid
Flag Indicator
FIGURE 3: INDICATING UNIT SHOWING TERMINALS AND MOUNTING HOLES

Sentinel™ EFI-MFZ-50 User’s Manual
Version 3.0 Page 8 of 15
4.3 REMOTE INDICATOR (OPTIONAL)
A remote indicator can be ordered separately or ordered pre-installed. The remote
indicator is designed to be mounted through a hole in the switchgear enclosure so that it is
visible from the outside.
5. OPERATION
5.1 CURRENT SENSOR
The Sentinel current sensor comprises of a flexible iron-core belt with a pickup coil. The
belt is fitted around the three-phase cable system being monitored and works on the core-
balance current sensing method. Under normal conditions the magnetic flux from the three
phase currents summates to zero and the pickup coil generates no voltage output. When
an earth fault occurs the summation flux is non-zero and a voltage proportional to the
magnitude of the earth fault is generated. The indicator unit is programmed to trip for a
nominal earth fault of 50 A. The current sensor has no exposed metal parts and is
completely encapsulated and corrosion proof.
5.2 INDICATING UNIT
The primary indication on the EFI-MFZ-50 is a mechanical Flag. The Flag will flip into a
tripped position after a fault is detected and flip into a reset position when the EFI is in a
reset state.
FIGURE 4: REMOTE INDICATOR
FRONT VIEW SIDE VIEW
Ø M10
20mm

Sentinel™ EFI-MFZ-50 User’s Manual
Version 3.0 Page 9 of 15
The indicating unit is powered from the mains supply and also uses the presence of
healthy mains to reset the unit. When healthy mains is first applied or when it returns after
a cleared fault condition, the unit will first require up to 5 minutes to charge the onboard
supply capacitors before it is functional. The presence of mains voltage will also reset the
unit if it is in a tripped state.
The indicating unit continuously monitors the output signal from the current sensor. The
current sensor transmits a voltage which is proportional to the measured current. For
primary currents in excess of 50A the current sensor saturates and a limiting circuit inside
the indicating unit clamps the output voltage to below 10V even for high fault currents.
When an imbalance is detected, onboard circuitry analyses the fault current. The
magnitude and duration of the half cycles of fault current are measured. Current spikes
and glitches are ignored. As soon as valid fault current has been detected, the Sentinel
triggers and enters a tripped state. A trip will flip the Flag into a tripped positon.
5.2.1 AUXILIARY RELAY (OPTIONAL)
An on-board auxiliary relay provides a potential-free, normally-open contact for additional
signaling. A 2-way screw terminal is provided on-board to which the user can connect a
signaling cable. The auxiliary relay is operated from the same circuitry controlling the Flag.
Thus when healthy mains is first applied or when it returns after a cleared fault condition,
the unit may require up to 5 minutes to charge the onboard supply capacitors after which it
then resets. A reset will latch the relay into the reset position (open). A tripped state will
latch the relay into a tripped position (closed).
5.2.2 REMOTE INDICATOR (OPTIONAL)
An optional remote indicator can be ordered pre-installed or ordered separately. A 2-way
screw terminal is provided on-board for connection of the remote indicator. It provides
flashing LED indication at some distance from the main indicating unit. During a tripped
state the unit will flash at a rate of about 1Hz. The remote indicator is weather-proof and is
housed inside a stainless steel bolt which also makes it vandal-proof. The on-board
circuitry which drives the remote indicator requires at least 5 minutes of mains charging
when first connected to the mains supply.
5.2.3 MANUAL TEST AND RESET
A pushbutton located on the front panel allows the unit to be manually tested or reset. The
button must be depressed for at least 3 seconds before it will activate. This is to avoid
accidental operation. The EFI can only be manually tested if the unit has been charged by
the mains supply for up to 5 minutes. The manual test feature can both trip and reset the
EFI.

Sentinel™ EFI-MFZ-50 User’s Manual
Version 3.0 Page 10 of 15
6. TESTING
The Sentinel EFI can be fully tested by injecting test current though the current sensor. A
test procedure is suggested below.
1. Connect the device to mains voltage for at least 5 minutes to charge the supply.
2. Inject 40 A for 1 second. The device should not trip.
3. Inject 60 A for at least 50 ms. The device should trip.
4. Apply mains voltage for 10 seconds. The device should reset.

Sentinel™ EFI-MFZ-50 User’s Manual
Version 3.0 Page 11 of 15
7. SPECIFICATIONS
Network voltage range: 1-36kV
Rated mains voltage: 110V-230V ±20%
Frequency: 50Hz / 60Hz ±20%
Overvoltage withstand: 600V for 48 hours
Impulse voltage withstand: 10kV, 1.2/50us waveform
Trip current: 50A ±10A
Minimum fault duration: 2.5 cycles (50ms @ 50Hz / 40ms @ 60Hz)
Fault current withstand: 25kA for 1s
Primary indication: Mechanical Flag
Voltage reset: Healthy mains for 10s
Manual test: Pushbutton alternately initiates trip and reset
Supply charging time: 5 minutes nominal
Operating temperature: -20ºC to 70ºC
Enclosure
-dimensions 115mm × 65mm × 40m
-material ABS, grey
-mounting Flush-mounting, two M4 holes
-degree of protection IP65
-cable gland size: PG7; cable diameter range 3-6.5mm
-mass: 250g
Current sensor
-CT100 (standard size): 100mm diameter
-CT150 (optional): 150mm diameter
-CT300 (optional): 300mm × 100mm rectangular oval
-material: Insulated silicon steel
-mounting: releasable cable-ties
-lead length: 3m
-lead type: 2-core, 0.5mm2, doubly insulated
-mass: 250g
Auxiliary relay
-type: Latching, N/O on reset
-rating: 220Vdc, 250Vac, 2A
Remote indicator
-dimensions: M10 Hex Bolt 20mm long (200g)
-material: Stainless steel
-mounting: Self-mounting through single M12 Hole
-lead length: 2m
-lead type: 2-core, 0.5mm2, doubly insulated
-degree of protection IP65

Sentinel™ EFI-MFZ-50 User’s Manual
Version 3.0 Page 12 of 15
-indication method Flashing LED
-flash rate: 1Hz nominal
-flashing duration: 12 hours nominal

Sentinel™ EFI-MFZ-50 User’s Manual
Version 3.0 Page 13 of 15
8. ORDERING
Table 1 below shows the codes to be used for product ordering. Only the first three code
groups need to be specified for the standard versions of the product. The standard
versions ships without the items from groups 4, 5 and 6, and with a standard size current
transformer (CT100 with 3m lead).
Please review the examples shown overleaf.
Group 1 Product Range EFI Earth Fault Indicator
M Mains powered
B Battery powered
Symbol 1: Power source
C CT powered
L LEDSymbol 2: Indicator type F Flag
Group 2
Symbol 3: Glands Z Cable glands fitted
Group 3 Nominal trip current in amps 50 50 amps trip level
Group 4 Symbol 1: Mains cable fitted M Mains cable
Symbol 2: Mains cable length in meters 3 3 meters
Group 5 Symbol 1: Remote indicator fitted R Remote indicator
Symbol 2: Remote cable length in meters 3 3 meters
Group 6 Symbol 1: Auxiliary relay fitted A Auxiliary relay
Symbol 2: Auxiliary cable length in meters 2 2 meters
Group 7 Symbol 1-5: Current transformer diameter CT100 100mm diameter
CT150 150mm diameter
CT300 300mm by 100mm
Group 8 Symbol 1: CT fitted C Current Sensor
Symbol 2: CT cable length in meters 3 3 meters
TABLE 1: ORDERING CODES

Sentinel™ EFI-MFZ-50 User’s Manual
Version 3.0 Page 14 of 15
For Example:
ORDERING CODE DESCRIPTION
EFI-MFZ-50 (standard version) - Mains powered
- Flag indication
- 50A trip
- CT diameter 100mm, 3m lead
EFI-MFZ-50-M5-R7-A2-CT150-C3 - Mains powered
- Flag indication
- 50A trip
- Mains cable, 5m lead
- Remote indicator, 7m lead
- Auxiliary relay, 2m lead
- CT diameter 150mm, 3m lead
NOTE:
• The mains lead is an optional component and must be specified if required.
• The remote indicator is an optional component and must be specified if required.
• The auxiliary relay is an optional component and must be specified if required.
• The unused cable-glands ship with a rubber stopper inserted to maintain sealing
integrity.
• The EFI unit ships in a brown corrugated cardboard box.

Sentinel™ EFI-MFZ-50 User’s Manual
Version 3.0 Page 15 of 15
9. WARRANTY
The Sentinel earth fault indicator electronic hardware and software is copyright Cybertronix
cc 1996.
This product is warranted to be free from defects in material and workmanship for a period
of twelve months (12) from the date of shipment. Correction shall be in the form of repair
or replacement of the defective items or components, freight paid by the customer both
ways. Such correction shall constitute a fulfillment of all Cybertronix cc liabilities in respect
to said items and components. In no event shall Cybertronix be liable for consequential
damage.
No other warranties:
To the maximum extent permitted by applicable law, Cybertronix cc disclaims all other
warranties, either express or implied, including but not limited to implied warranties of
merchantability and fitness for a particular purpose, with respect to the Sentinel product
and accompanying product manual. Cybertronix cc makes no representation or warranty
that the product is 'error free', or meets any user's particular standards, requirements or
needs.
Disclaimer:
To the maximum extent permitted by the applicable law, in no event shall Cybertronix cc
be liable to the user for any special, indirect, consequential or similar damages, including
any lost profits or lost data arising out of the use or inability to use the product or
documentation or any other data supplied therewith even if the seller or anyone else has
been advised of the possibility of such damages, or for any claim by any other party. In the
event of the above limitation not applying to the user, then in no case shall the Cybertronix
cc liability exceed the original purchase price of the product.