Ground Fault Systems DGF100 User manual

DGF100 Digital Ground Fault unit
reference manual
www.groundfaultsystems.com
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Tel: [phone]
CofC: 55400914
Ground Fault Systems B.V.
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CONTENTS PAGE 2OF 26
DGF100 reference manual, rev 1, Feb 22, 2022 Ground Fault Systems B.V.
1. GENERAL DESCRIPTION 3
2. FUNCTIONALITY 4
2.1 Dipswitch settings 4
2.1.1 CS configuration / Dipswitch 1 4
2.1.2 Ground Fault Trip Current level –dipswitches 2, 3, 4 & 5 4
2.1.3 Ground Fault Trip Delay Time –dipswitches 6, 7 & 8 4
2.1.4 Operating mode –dipswitches 9 & 10 5
2.2 LED Indicators 6
2.3 Reset/Test pushbutton 6
2.4 External Current Sensor 7
2.5 Frame Bonding/Chassis Ground 7
2.6 DGF100 Display 8
3. CONTROL VOLTAGE ERROR! BOOKMARK NOT DEFINED.
4. CONNECTIONS AND PRECAUTIONS 11
5. CATALOG NUMBERS 13
6. TECHNICAL SPECIFICATIONS 14
6.1 Ground fault circuit 14
6.2 External pushbutton circuit 14
6.3 Control Voltage Error! Bookmark not defined.
6.4 System power 15
6.5 Terminals 15
6.6 Relay contacts 16
6.7 Mechanical properties (installed) 16
6.8 Display datalink circuit 17
6.9 Environment 17
7. APPLICABLE STANDARDS 18
8. TABLES AND FIGURES 19
8.1 Table 1 - Dipswitch settings 19
8.2 Table 2 - Primary current Trip Level 20
8.3 Tables 3 - Trip Time Accuracy 21
8.3.1 Table 3a - Current level 0,030 –2,5 A 21
8.3.2 Table 3b - Current level 4 A 21
8.3.3 Table 3c - Current level 6 A 22
8.3.4 Table 3d - Current level 9 A 22
8.4 Figure 1 - Typical field connection using built-in Current Sensor, remote test/reset and
DGF100 Display 23
8.5 Figure 2 - Typical field connection with external Current Sensor and DGF100 display 24
8.6 Figure 3 - Typical field connection with interposing Current Transformer and DGF100 display 25
8.7 Figure 4 - Dimensions DGF100 26
8.8 Figure 5 - Connection multiple DGF100s 26

PAGE 3OF 26
DGF100 reference manual, rev 1, Feb 22, 2022 Ground Fault Systems B.V.
1. GENERAL DESCRIPTION
The DGF100 is a microprocessor based ground fault unit for use on solidly grounded or resistance
grounded systems. This innovative digital electronic unit measures ground fault current using a built-in
46 mm zero sequence Current Sensor (CS), or an external Current Sensor. External Current Sensors with
different cable windows, round or square, and various current ratios are available. The external current
sensors must be connected to terminals T1 & T2.
The system will react to alternating current (ac) only and will reject direct current (dc) signals. Accuracy
will be maintained over a frequency range of 40-65 or 400 Hz, making it suitable for variable frequency
drive applications. The DGF100 is a Class A device as defined in the IEC 60755 standard; it is therefore
fully characterized for operation with sinusoidal ac and pulsating dc currents.
The DGF100 houses an isolated universal power supply from 24-240 V ac or dc and is equipped with form
‘Z’ (4-wire) isolated N.O and N.C. contacts. The Ground Fault (G/ F) Current Trip level (30mA-9A, 14
steps), Trip Delay Time (20ms–5s, 8 steps) and the Relay Operating Mode (F/S, non-F/S, pulsed auto
reset and pulsed Non-FS) are set on a front accessible dipswitch array.
A single press of the RESET button, or an external, voltage free, momentary pushbutton connected to
terminals R1 and T2/R2, resets the relay after a trip. A functional test of the DGF100 is started by either
double clicking the cover mounted or external button, or by invoking a test on the DGF100 Display.
A green RUN LED flashes, alternating one second on and off, to indicate that sufficient control power is
applied to terminals L+ and N- (Power OK).
A red TRIP LED indicates that the DGF100 has sensed a Ground Fault and that the output contacts have
operated.
7 point and 3 point pull-apart terminal blocks simplifies connection of field wiring. A captive screw
secures the 7 point block to the relay, safe from the effects of shock and vibration.
A communications port provides access for a remote display. The remote DGF100 Display shows the
actual ground fault current during normal running of the systems. After a trip the ground fault current
just prior to the trip is displayed. If the DGF100 Display was connected to the DGF100 at the moment of
a trip and the DGF100’s Control Voltage is turned off, pressing the VERIFY button will show a red LED
indicating a ground fault. If no fault was present the green LED will light.
For all features, see the Instruction Manual for the DGF100 Display.
To ensure that the DGF100 will function in all circumstances, it is encapsulated in polyurethane (PUR) to
make sure it is not vulnerable to mechanical shock, vibration nor weather.
The maximum system operating voltage for the DGF100 is 660 V, when passing the system power
conductors through the built-in CS. However, by using any GFS external CS and insulating the busbars, or
by using any suitably rated, commercially available, interposing CT and passing the secondary lead
through the built-in CS, the relay can be used on any system voltage.

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DGF100 reference manual, rev 1, Feb 22, 2022 Ground Fault Systems B.V.
2. FUNCTIONALITY
2.1 Dipswitch settings
FOR MAXIMUM SAFETY OF PERSONNEL AND EQUIPMENT, THE SETTINGS SHOULD BE MADE
WITH THE SYSTEM POWER SWITCHED OFF.
Inadvertent changes in settings can cause unexpected trips and unforeseen reactions.
The DGF100 has dipswitches to set the desired Trip Current level, Trip Delay time, Relay Operating Mode
and CS configuration. Below is a summary of the different options. See table 1 for the setting values.
2.1.1 CS configuration /Dipswitch 1
The DGF100 is capable of measuring primary ground fault currents from 10 mA - 10000 A with trip level
settings in different ranges:
30 mA - 9.0 A with the system power conductors passing through the built-in 46 mm CS.
30 mA - 9.0 A with the system power conductors passing through an external CS with a
current ratio of 500:1 with its secondary terminals connected to terminals T1 & T2.
60 mA –18,0 A with the system power conductors passing through an external CS with a
current ratio of 1000:1 with its secondary terminals connected to terminals T1 & T2.
120 mA –36,0 A with the system power conductors passing through an external CS with a
current ratio of 2000:1 with its secondary terminals connected to terminals T1 & T2.
600 mA –180 A with the system power conductors passing through an external CS with a
current ratio of 10.000:1 with its secondary terminals connected to terminals T1 & T2.
3.0 - 900 A by passing the 5 A secondary of an interposing CT with a
current ratio of 500:5 through the built-in 46 mm CS.
30 - 9000 A by passing the 5 A secondary of an interposing CT with a
current ratio of 5000:5 through the built-in 46 mm CS.
See Table 1.
2.1.2 Ground Fault Trip Current level –dipswitches 2, 3, 4&5
The Ground Fault Trip Current level is 30 mA - 9000 A in different ranges. Table 1 provides a list of the
fourteen Trip Current level settings in each of three ranges, which can be made on dipswitches 2, 3, 4, &
5, depending on the CS configuration selected as described in the above paragraph, 2.1.1.
It is recommended that the Ground Fault Trip level be kept as close to the charging current as possible.
This will provide maximum safety for operating personnel and equipment.
On resistance grounded systems, the Trip Current level should be set lower than 20% of the Neutral
Grounding Resistor let-through current.
2.1.3 Ground Fault Trip Delay Time –dipswitches 6, 7&8
The ground fault Trip Delay time range is 20 ms - 5.0 s. Table 1 provides a list of the eight Trip Delay
time settings, which can be made with dipswitches 6, 7 and 8.
Set the Ground Fault Trip Delay time to provide the desired delay before the output relay changes state
when the ground fault Trip Delay level is reached or exceeded and the Trip Delay time has expired.
The setting should be selected to co-ordinate with other ground-fault devices connected on the same
power transformer secondary: set shorter than upstream devices; set longer than downstream devices. If
no other ground-fault devices are connected, set for the shortest possible time.

PAGE 5OF 26
DGF100 reference manual, rev 1, Feb 22, 2022 Ground Fault Systems B.V.
2.1.4 Operating mode –dipswitches 9&10
(N.O. = Normally Open, N.C. = Normally Closed)
The DGF100 user can select four distinct Operating Modes for the device.
All modes have in common:
In the ‘reset state’ of the relay the N.O. contact is open and the N.C. contact is closed.
In the ‘tripped state’ of the relay the N.O. contact is closed and the N.C. contact is open.
See table 1 for the dipswitch-settings.
The different modes are listed below:
1. Non-Failsafe operation
The output relay does not change state when Control Voltage is applied.
With Control Voltage on (Green RUN LED flashing), when the measured value reaches or exceeds
the settings for current and time, the output relay changes state (trips) and the red TRIP LED lights.
If Control Voltage is maintained after a ground fault trip, the reset button must be pushed to reset
the relay after clearing the ground fault.
If Control Voltage is removed while a ground fault is detected, the output relay resets and the red
TRIP LED is turned off.
If the ground fault has not been cleared when Control Voltage is restored, the relay will trip and the
red TRIP LED will light after 500 milliseconds, regardless of the Trip Delay time.
If the ground fault has been cleared when Control Voltage is restored, the relay will remain reset
and the green RUN LED flashes.
The Non-Failsafe mode can be used when the output relay is operating under-voltage devices. This
includes: contactor coils; starter coils and circuit breakers equipped with UV trip coils.
2. Failsafe operation
The output relay contacts change state 500 ms after Control Voltage is applied.
The output relay trips when either or both of the following conditions occur:
The measured values reach or exceed the settings for current during the delay time. In this
condition the red TRIP LED lights.
Control Voltage is removed. In this condition the red TRIP LED does not light.
If Control Voltage is maintained after a ground fault trip, the reset button must be pushed to reset
the relay after clearing the ground fault.
If Control Voltage is removed after a ground fault is detected, the output relay remains tripped.
If the ground fault has not been cleared when Control Voltage is restored, the relay remains tripped.
If the ground fault has been cleared when Control Voltage is restored, the relay contacts will change
state 500 ms after Control Voltage is applied.
The Failsafe mode can be used to trip the DGF100 upon loss of Control Voltage.
The Failsafe mode can be used when the output relay is operating undervoltage (UV) devices. This
includes: contactor coils; starter coils; and circuit breakers equipped with UV trip coils provided that
the Control Voltage to the DGF100 is not interrupted by the action of the UV trip.
3. Auto Reset operation
The output relay does not change state when Control Voltage is applied.
With Control Voltage on (green RUN LED flashing), when the measured value reaches or exceeds
the settings for current during the delay time, the output relay changes state (trips) and the red
TRIP LED lights. The output relay will remain tripped until one of the following conditions is met:
Three seconds after the ground fault current drops below the trip current set point the relay will
reset and the red TRIP LED is turned off.
If the Control Voltage is removed by the trip action of the output relay (i.e. it operates the
shunt trip of the breaker that is providing the Control Voltage), the relay will reset with a short
delay and the red TRIP LED is turned off.
If the ground fault has not been cleared when Control Voltage is restored, the unit will trip after 500
milliseconds, regardless of the Trip Delay time, the above cycle will be repeated.
If the ground fault has been cleared when Control Voltage is restored, the unit will remain in reset
state.
The Auto Reset mode is designed for applications where the output relay is operating a shunt trip

PAGE 6OF 26
DGF100 reference manual, rev 1, Feb 22, 2022 Ground Fault Systems B.V.
device. The DGF100 resets automatically 3 seconds after the ground fault current is interrupted by
the tripping action of the circuit breaker. The output contact to the shunt trip coil opens. This
prevents damage to the internal mechanism of the circuit breaker in the event that the operator tries
to reset the circuit breaker. When the Control Voltage to the DGF100 is interrupted by action of the
shunt trip, the DGF100 resets with a short delay.
4. Pulsed Non-failsafe Operation
The output relay does not change state when Control Voltage is applied or removed.
With Control Voltage on (green RUN LED alternating flashing one second on and off), when the
measured value reaches or exceeds the settings for current and time, the relay goes to the tripped
state for 0.5 seconds, then resets. The red TRIP LED will light.
Should the measured current remain or go above the set G/F trip level, this 0,5 second pulse is
repeated every 3 seconds. The red TRIP LED remains on until a RESET is activated. This allows the
user to verify which DGF100 tripped its associated breaker. If a RESET is not activated the red TRIP
LED remains on showing the cause of trip. However, the functionality of the trip circuit is not
compromised. That is, in case of a trip condition the relay will correctly issue a pulse, even if the red
TRIP LED is on.
If the Control Voltage is removed by the trip action of the output relay (i.e. it operates the shunt trip
of the breaker that is providing the Control Voltage) the red TRIP LED is turned off.
If the ground fault has not been cleared when Control Voltage is restored, regardless of the Trip
Delay time, after 500 milliseconds the relay goes to the tripped state for 0,5 seconds, then resets.
The red TRIP LED will turn on.
If the ground fault has been cleared when Control Voltage is restored, the unit will remain in reset
state and the green LED will flash.
If the DGF100 is to be used for alarm only purposes (rather than to interrupt ongoing processes), and the
alarm has to have an auto-resetting nature, then one has to use one of the Pulsed modes. The pulses will
be repeated as long as current is above the set G/F level.
Back to Control Voltage. Back to Reset/Test pushbutton
2.2 LED Indicators
There are two LEDs on the front of the DGF100:
A green LED showing sufficient Control Voltage by slowly flashing (1 s on / 1 s off).
A red LED, if steady on, indicating a trip.
2.3 Reset/Test pushbutton
Either the built-in or an external, normally open, momentary pushbutton, connected to terminals R1 and
T2/R2, is used to reset the internal relay and/or the red LED (depending on the Operating Mode, see
section 2.1.4). The external reset button must be a momentary normally open voltage-free contact; no
external power supply is required. See section 6.2.
A reset will only be granted if the cause of the trip is cleared. Otherwise the relay will remain activated
without glitches.
Double-clicking the built-in or external reset button invokes a test which switches an AC test-voltage onto
the built-in processor’s CS input. The voltage is scaled to simulate a residual current of 1,5 - 3 times the
G/F trip level. The unit will trip on G/F after the set delay (plus 0,4 s). The red LED turns on solidly. The
button needs to be pressed again to reset the device.
It is NOT necessary to press the RESET button after the ground fault has been cleared when the DGF100
is set in the Pulsed Auto Reset mode. In this mode the relay will reset in 3 seconds.
Back to DGF100 Display.

PAGE 7OF 26
DGF100 reference manual, rev 1, Feb 22, 2022 Ground Fault Systems B.V.
2.4 External Current Sensor
The DGF100 can work with an external CS, which is useful in the situation where the cables together are
bigger than the 46 mm of the internal CS opening allows, or when higher than 660V system voltages are
needed.
See Catalog Numbers for the available options and Table 2 for the various trip values.
2.5 Frame Bonding/Chassis Ground
Chassis ground is the ground to which all of the non-current carrying metal equipment is
connected/bonded.
In order to meet the Electromagnetic Compatibility (EMC) requirements a firm and short connection is
required between terminal FB and the chassis ground point. The chassis ground must not be more than
50 mm away from the unit.
If the DGF100 is mounted on a 35 mm DIN rail, a ‘DIN rail ground terminal block’ can be installed beside
the unit to act as the chassis ground point. Use a 2-2,5 mm2(14 AWG) stranded conductor.
See the figures 1, 2 and 3 on typical field connections.
Back to Connections and precautions.

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DGF100 reference manual, rev 1, Feb 22, 2022 Ground Fault Systems B.V.
2.6 DGF100 Display
The door mounted DGF100 Display is connected to the DGF100 by up to 10 m of RJ-10 type, 4-wire
telephone type cable. It provides the following remote indications and functions:
Continuous reading of actual ground fault current, employing auto ranging.
‘RESET’ pushbutton. To reset the unit after a trip.
‘VERIFY’ pushbutton. By pushing the ‘VERIFY’ button on the DGF100 Display, it will show if the
DGF100, to which it was connected at the time of trip, tripped due to a ground fault prior to loss of
its Control Voltage by lighting the red ‘G/ F TRIP’LED. If there was no ground fault trip prior to loss
of Control Voltage the green ‘RUN’LED will light. This feature is especially useful when pulse tripping
a breaker that also supplies Control Voltage to the DGF100. This indication will remain available for
at least ten hours. The DGF100 Display will reset automatically when Control Voltage is restored.
‘TEST’ pushbutton. (See section 2.3 Ground Fault Test for a description of the test procedure).
The ‘RESET’ button must be held pressed before the ‘TEST’ is pressed to invoke the test procedure.
The function of this button can be enabled/ disabled by inserting the interconnecting cable from the
DGF100 base unit into one of two sockets, TEST ON or TEST OFF, on the right side of the display. If
the feature is disabled and the ‘RESET’ and ‘TEST’ buttons are pressed, the display shows ‘OFF’ for 1
second, and the red ‘G/F TRIP’ LED on the display flashes twice.
Display of the pre-trip ground fault current, after a trip has occurred (flashing display).
When the G/F current exceeds the system’s measuring range, the display shows Out , meaning
‘Out of range’.
Power over datalink, no external power supply needed
There are two LEDs present, green and red, showing which state the DGF100 base unit is in.
-Green ‘RUN’LED Flashing: Okay
Off: No Control Voltage, Control Voltage too low
-Red ‘G/F TRIP’LED Off: No trip
Steady on: Trip
After loss of Control Voltage the DGF100 base unit will show if it tripped because of a ground fault,
by lighting the red LED, or if it was a loss of Control Voltage without a trip, by lighting the green
LED.

PAGE 9OF 26
DGF100 reference manual, rev 1, Feb 22, 2022 Ground Fault Systems B.V.
The Numerical LCD window displays actual ground fault current in A. When a 5000:5 ratio interposing CT
is used, all displayed values are to be interpreted as kA rather than A.
Two blank boxes to the right of the LCD display window are marked ‘A’ and ‘kA’. Use a permanent marker
to check the appropriate box as follows:
‘A’ - when using the built-in CS, an external CS, or a 500:5 ratio interposing CT.
‘kA’ - when using a 5000:5 ratio interposing CT.

PAGE 10 OF 26
DGF100 reference manual, rev 1, Feb 22, 2022 Ground Fault Systems B.V.
3. CONTROL VOLTAGE
The DGF100 has a universal, isolated power supply, accepting nominal voltages between 24 and 240 V ac
or dc with -20% / +10% tolerances. The total range of accepted voltages is therefore 19,2 to 264 V ac or
dc. Power consumption is a mere 1,2 VA maximum with ac voltages and 0,5 W maximum with dc
voltages.
For optimum EMC performance and safety, the FB (Frame Bond) terminal must be firmly connected to
the local frame or chassis ground. The chassis ground must not be more than 50 mm away from the unit.
If the DGF100 is mounted on a 35 mm DIN rail, a ‘DIN rail ground terminal block’ can be installed beside
the unit to act as the chassis ground point. Use a 2-2,5 mm2(14 AWG) stranded conductor.
Control Voltage is subsequently presented to the L+ and N- terminals.
For good EMC behaviour it is important (as in any installation) to run all wiring close along the chassis or
in metal ducts, avoiding excess lengths and coiled up wires.