PUB 50411
D64RP18 SERIES B1 DIGITAL GROUND FAULT RELAY
Revision 2
May, 2005
Page 3
1.
GENERAL DESCRIPTION
The
D64RP18
is a microprocessor based ground fault relay for use on solidly grounded or resistance
grounded systems. This innovative digital electronic relay measures ground fault current using a built-in 1.1”
zero sequence current transformer (CT).
The
D64RP18
reacts to alternating current only and will reject direct current signals. It will maintain accuracy
over a frequency range of 45 to 450Hz, making it suitable for variable frequency drive applications.
660 Volts is the maximum system operating voltage for the D64RP18 when passing the system power
conductors through the built-in CT. However, by using any Eaton’s Cutler-Hammer C311CT zero sequence
current transformers with 500:1 ratio, connecting the secondary to terminals T1 and T2 of the relay, and
passing the system insulated power conductors through the window of this CT, the D64RP18 can be applied
on any system voltage.
The ground fault current trip level is set on a front accessible binary DIPswitch array. Trip currents from 30
milliamps - 6 Amps can be selected in 8 discrete steps. These same trip settings are available when using any
C311CT 500:1 ratio external CT. The trip level can be set just above the charging current
1
. Any deterioration in
the circuit will trip the relay. This also permits scheduled field testing of the relay (by lowering the trip level).
1
The capacitance-to-ground charging current on a system will vary depending on: the overall length of
the cables; the types of loads; the quality of insulation on the phase conductors; the surrounding
equipment grounding, cable trays, junction boxes, etc.; and, the type of transformer.
A "Rule-of-Thumb" for systems 600 Volts and lower: The charging current is 0.5 Amps per 1000 kVA
of transformer capacity.
The response time on ground fault trip is set on a single front accessible DIPswitch. The two settings are
instantaneous (20 ms) or 500 ms.
The output relay has Form “Z” (4 terminal) N.O. and N.C. contacts which may be used to operate the upstream
protective device and to indicate a failure of the system. The relay will operate in one of two modes: Non-
failsafe; or Pulsed Output Auto Reset. The mode is established by the type of pushbutton (or jumper)
connected to terminals R1 and R2: N.O. = Non-failsafe; N.C. (or jumper) = Pulsed Output Auto Reset.
By double clicking the remote RESET button connected to terminals R1 and R2, a functional test of the
D64RP18 is invoked. A single press of a N.O. contact remote RESET button resets the relay after a trip. (It is
not necessary to press a N.C. contact remote RESET to invoke Auto Reset). The green LED indicates two
functions: When slow flashing it denotes control power is applied to terminals N- and L+; when fast blinking it
denotes the relay has sensed a ground fault current higher than the trip level for a period longer than the trip
time and that the output contacts have operated.
A 10 point Pull-apart terminal block simplifies connection of field wiring.
The D64RP18 operates on any control voltage from 24 to 240 Volts ac or dc.
2.
OPERATION
2.1
GLOSSARY OF TERMS
Manual Reset:
A N.O. contact remote RESET pushbutton connected to terminals R1 and R2 of the D64RP18
must be pressed once to reset the output relay after a trip, providing the ground fault has been
cleared or the measured values are within the preset limits.
