The DGF7-14 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 28 mm zero sequence Current Sensor (CS), or an external CS.
(Go to Sensors.)
External CSs with different cable windows, round or square and split core, and various current ratios are available.
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
45 - 450 Hz, making it suitable for variable frequency drive applications. The DGF7-14 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 maximum system operating voltage for the DGF7-14 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 unit can be used on any system voltage.
The DGF7-14 houses a non-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 Current Trip level (1 – 10 A, 8 steps), Trip Delay Time (500 ms – 10 s, 8 steps) and the Relay Operating Mode (Continuous Non-Failsafe,
Continuous Failsafe, Pulsed Auto Reset, Pulsed Non-Failsafe) are set on a front accessible dipswitch array.
A single press of an external, voltage free, momentary button resets the unit after a trip. A functional test of the DGF7-14 is started by double clicking
the external button. WARNING: invoking a test will and must trip the installation!
A green LED indicates three functions: slow flashes denotes Control Voltage is present (1 s flashes); steady on after a test was invoked; fast flashes
denotes the unit has sensed a ground fault current higher than the Trip Level for a period longer than the Trip Delay Time and that the output contacts
have operated (0,25 s flashes).
A 12 point Pull-apart terminal block with 12 AWG screw clamps per pole (Double Row - T Connector) simplifies connection of field wiring.
Terminals are provided for connection of an external voltmeter. The output is 0 to 10 V, proportional to the Trip Current Level set on the dipswitches.
The DGF7-14 is equipped with an aluminium profile enabling horizontal mounting on a DIN rail.
To insure that the DGF7-14 will function in severe circumstances, it is encapsulated in polyurethane (PUR) to make sure it is not vulnerable to
mechanical shock, vibration nor weather.