IL04915001E
Effective 7/09
1
Instructions for D64RPB30 Series C1 Ground Fault Relay
S1
1
2
3
4
5
6
7
8
O
N
1
2
3
4
5
6
7
8
O
N
2 = S/C
4 = CT
F
2
0
2
4
-0
1
-0
1
2
4
-2
4
0
V
A
C
/
D
C
C
T
N
.C
.
N
.O
.
DOUBLE CLICK
FOR TEST
T
FLASHES:
1 = E/F
3 = BACKUP
5 = F/S CV LOSS
CONT’ = TRIP FAILED
& OTHER
2 = S/C
4 = CT
RATINGS PER IEC 60755:
In
I n
F
= SEE EACH CT MAX.
= 0.03 - 9 A
= 45 - 450 Hz
Cat. No.
D64RPB30
Figure 1. D64RPB30 Ground Fault Relay
1. FUNCTIONALITY
1.1 Ground fault current sensing and fault
reporting
The D64RPB30 is a microprocessor based
ground fault relay for use on solidly grounded or
resistance grounded systems.
The D64RPB30 employs an external 500:1
current transformer (CT) to measure ground
fault current flowing to ground in electrical power
distribution systems. The measured value is
compared against two setpoints. The lower one,
the Ground fault (G/F) setpoint, is settable from
30 mA to 9 A in 8 steps and has an associated
delay settable from 20 ms to 10 s in 6 steps. The
higher one, the Short Circuit (S/C) setpoint is
fixed at 125 A. When the current exceeds the
G/F setpoint for the set delay, but does not
reach the S/C level, a ‘G/F’ is diagnosed and the
unit trips by operating its internal relay. Should a
fault occur causing a ground fault current
exceeding the S/C setpoint, the D64RPB30
operates its relay without any delay diagnosing
an ‘S/C’.
Optionally, the user can select the operation of
the relay to be Type 2 Coordinated with an
upstream tripping device (fuse or breaker) to
protect any local contactor contacts in the case
of S/C faults. In this case the unit does not trip
initially when the measured current exceeds the
S/C setpoint, but waits for the upstream device
to take care of current interruption and then
trips. The latter trip flags the location of the fault
to the user and also allows him to instantly re-
close the upstream tripping device. Should the
upstream device fail to perform, then automatic
backup protection makes the D64RPB30 trip -as
a last resort- 20 ms or 300 ms, selected by
dipswitch, after the S/C occurred.
The relay contacts can be used in a trip or alarm
circuit. Form “Z”, normally open and normally
closed contacts is provided.
The D64RPB30 is a Class A device as defined
in the IEC 60755 standard; therefore it is
designed for operation with sinusoidal AC and
pulsating DC currents.
1.2 External CT supervision
With any G/F protection scheme using an
external CT, there is an inherent risk that ground
faults will not be detected because of a bad or
deteriorated connection to the CT. Both open
circuits and shorts on the CT connection will
prevent detection. Therefore, the conventional
practice is to prove correct tripping regularly by
means of current injection. This is an annoying
procedure disrupting normal plant operation.
The D64RPB30 solves this problem by
constantly supervising the connection to the
external CT. Open circuits as well as shorts are
detected and will cause a trip.
Please note that the D64RPB30 does not
employ any DC injection to implement this
feature. Even small DC currents sent through
the secondary of a CT can bias its core enough
to shift the trip point outside specification on
sensitive settings.
