Effective 11/2003
Page 11
I.L. 66A7535H02
The block close function can be further set up for “AUTO”
or “MANUAL” resetting after a trip event. This is
accomplished by entering the SYSTEM menu and
programming the B and C relay as desired. The Digitrip
1150V/V
i
can also be reset via PowerNet or BIM
communications.
1.7 UL, CSA and CE Recognition
The Digitrip 1150V and Digitrip 1150V
i
Trip Units are UL
(Underwriters Laboratories, Inc.)
Recognized Components
under Files E52096 and E146559 for use in Type VCP-T,
VCP-TR and Type T-VAC, T-VACR Medium Voltage
Circuit Breakers. They have also been tested by the
Canadian Standards Association (CSA).
These units have also passed the IEC 947-2 test program
which includes radiated and conducted emissions testing.
As a result, these units carry the CE mark.
Figure 1.7 Power/Relay Module for 1150V Trip Unit
three components:
1. The sensors, which measure the current level
2. The Digitrip Trip Unit, which provides a tripping signal to
the Trip Actuator, when current and time delay settings
are exceeded.
3. The low-energy Trip Actuator, which actually trips the
circuit breaker.
This arrangement provides a very flexible system, covering
a wide range of tripping characteristics described by the
time-current curves referenced in Section 9.2.
2.2 Low-Energy Trip Actuator
The mechanical force required to initiate the tripping action
of the circuit breaker is provided by a special low-energy
Trip Actuator. This device is located behind the molded
platform on which the Digitrip 1150V unit is supported.
(See Figure 1.2)
The Trip Actuator contains a permanent
magnet assembly, moving and stationary core assemblies,
a spring, and a coil. Nominal coil resistance is 24 ohms
and the black lead is positive. The circuit breaker mecha-
nism automatically resets the Trip Actuator each time the
circuit breaker opens.
When the Trip Actuator is reset by the operating mecha-
nism, the moving core assembly is held in readiness
against the force of the compressed spring by the perma-
nent magnet. When a tripping action is initiated, the low-
energy Trip Actuator coil receives a tripping pulse from the
Digitrip 1150V trip unit. This pulse overcomes the holding
effect of the permanent magnet, and the moving core is
released to upset the trip latch of the circuit breaker
mechanism.
2.3 Ground Fault Protection
2.3.1 General
When employing a ground fault scheme, the distribution
system characteristics
(i.e. system grounding, number of
sources, number and location of ground points, etc.)
must
be considered along with the manner and location in which
the circuit breaker is applied to the system. These ele-
ments are discussed in Section 2.3.2
through 2.3.4.
The Digitrip 1150V uses two modes of sensing to detect
ground fault currents: residual and zero sequence
(See
Table 2.1)
. The breaker’s secondary contact inputs B-6, B-
7, that were shown in Figure 1.6, are used to configure the
breaker cell positions for the two schemes. Having no
jumper from B-6 to B-7 programs the unit for a residual
ground fault scheme, while installing a jumper from B-6 to
B-7 programs the unit for zero sequence configuration. If
2.0 GENERAL DESCRIPTION of VCP-T, VCP-TR or
T-VAC, T-VACR CIRCUIT BREAKERS
2.1 General
The circuit breakers are tripped automatically on overload
and fault current conditions by the combined action of
