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Instruction Booklet IB 33-790-1J
Effective November 2010
Instructions for Low Voltage Power
Circuit Breakers Types DS and DSL
EATON CORPORATION www.eaton.com
Each Amptector I-A trip unit has a terminal block
equipped with test plug terminals accessible on the front
of the circuit breaker front panel. This permits convenient
field checking of calibrations and operation with an exter-
nal power supply. A specially designed power supply test
kit, with plugs to match the Amptector trip unit test plug
terminals is available; and its operation is described in
Section 8.7 6 of this instruction book.
Figure 59 shows a
typical standard wiring diagram, which
includes the Amptector trip unit terminal block. The fol-
lowing table explains the markings of the terminals.
A Sensor phase A
B Sensor phase B
C Sensor phase C
N Sensor neutral
G Ground
OP Output positive*
ON Output negative*
DN Test point (internal neutral)**
DS Test point**
TP Test point **
OSS High load switch signal to accessory unit
DI Test point **
*To Actuator Coil. THIS COIL HAS A POLARITY MARK-
ING ON THE POSITIVE LEAD WHICH MUST
BE
OBSERVED. OTHERWISE THE BREAKER WILL NOT
HAVE OVERLOAD OR FAULT PROTECTION WHICH
COULD RESULT IN BODILY INJURY AND/OR SERI-
OUS EQUIPMENT DAMAGE.
**Terminals marked “test point” are intended to provide
connections for operation of the optional test kit.
8.2.1 Ground Fault Protection
When the Amptector l-A trip unit includes ground current
protection, the type of connection to the circuit must be
considered. If the system neutral is grounded but the
neutral is not carried with
the phase conductors, the
Amptector trip unit has all of the equipment necessary for
sensitive ground protection.
If the system neutral is grounded and a neutral conductor
is carried with the phase conductors, it is necessary to
order an additional sensor, for the purpose of cancelling
out any residual current in the phase conductors. This
sensor must be mounted separately and must be located
on the neutral conductor at the point where the neutral
conductor connects t
o the neutral bus. These sensors
are duplicate of those supplied on the breaker except for
the 2400A and 3200A ratings where a modified neutral
sensor is required.
The Amptector trip unit ground element may be ener-
gized from an external ground current source rather than
from internally developed ground current. Such an exter-
nal source could be a ring-type transformer through
which all the load current conductors would have to pass.
In the case of a three-p
hase four-wire circuit all three
phase conductors and the neutral conductors would have
to pass through the transformer. The sensitivity of the
ground element for this kind of arrangement would
depend on the ratio of the transformer used.
The ground current pick-up dial on the Amptector l-A trip
unit has alphabetic calibration markings. The actual
ground current corresponding to these calibrated points
varies with the rating of the sensor being used. These
pick-up values
are printed on the top of the trip unit box.
The “Ground Trip Indicator” is a metal plunger located at
the upper right corner of the trip unit. If the trip unit has
functioned due to a ground fault, this plunger will protrude
through the faceplate of the unit. The indicator is reset by
pushing in on the plunger. If it is not reset before placing
the breaker back in service, the trip unit will function nor-
mally but there will remain a false indication.
Overloa
d Trip Indicator - Functions due to overload cur-
rents less than short delay or instantaneous pick-up.
Short Circuit Trip Indicator - Functions due to fault cur-
rent in excess of short delay or instantaneous pick-up.
8.3 MAKING CURRENT RELEASE (DISCRIMINATOR)
All Amptector trip units which do not have instantaneous
trip elements (Amptector II-A model SE and Amptector
l-A models LS and LSG) are provided with a “making cur-
rent release” which is referred to as a “Discriminato
r”.
This is a circuit in the trip unit which determines at the
time of a fault whether or not there has been any current
flow in the primary circuit previous to the fault. If there
has been no measurable current flow previous to the
fault, indicating that the circuit breaker is just being
closed (or possibly that a switching device ahead of the
breaker has just been closed) and if the primary current
flow exceeds approximately twelve times the sensor rat-
ing, the tr
ip unit will function instantaneously. If the “Dis-
criminator” circuit determines that there has been a
measurable current flow prior to the fault, the instanta-
neous operation will not occur and the normal short time
delay element will take over to delay tripping. The pur-
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