PUB 51079
D64RP14 SERIES A2 DIGITAL GROUND FAULT RELAY
Revision 1
May, 2005
Page 3
1.
GENERAL DESCRIPTION
The D64RP14 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 D64RP14 reacts to alternating current only and will reject direct current signals. It will maintain accuracy
over a frequency range of 45 to 65Hz, filtering out harmonics which could cause nuisance tripping, making it
ideal for use on systems employing static switching.
The D64RP14 is designed for use with neutral grounding resistors (NGRs) having let through currents from 2
Amps to 10 Amps.
660 Volts is the maximum system operating voltage for the D64RP14 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 D64RP14 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 1 Amp -
10 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).
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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 front accessible binary DIPswitch array. Trip times from 0.5
seconds to 10.0 seconds can be selected in 8 discrete steps.
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 can be set to operate in any one of the
following modes: Failsafe; Non-failsafe; or Pulsed Output Auto Reset by means of front accessible
DIPswitches.
By double clicking the remote Test/Reset button connected to terminals R1 and R2, a functional test of the
D64RP14 is invoked. A single press of the remote Test/Reset button resets the relay after a trip. (It is not
necessary to press the remote Test/Reset button 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.
Terminal blocks are provided for connection of an external voltmeter. The output is 0 to 10 Volts proportional to
the Trip current level set on the DIPswitches. For example: If the trip current level is set at 4 amps, the 0 – 10
Volts would be proportional to 0 – 4 Amps.
The 12 point terminal block is pull-apart and has two 12 AWG screw clamps per pole (Double Row T
Connector) simplifying connection of field wiring.
The D64RP14 operates on any control voltage from 24 to 240 Volts ac or dc.
