GE Entellisys 4.0 Application Manual Download

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Entellisys Low-Voltage Switchgear
Section 7. Protection

Entellisys low-voltage switchgear offers a broad
array of familiar and expanded protection capabili-
ties. All modes of protection except high-resistance
ground-fault detection are available from every
CPU without additional hardware. If your Entellisys
equipment does not have the type of protection
enabled that your power distribution system needs
now, it can probably be easily added.

The Entellisys centralized single-processor system
provides backup protection at the individual circuit
breaker level. It offers overcurrent protection using
traditional inverse-time characteristics, plus single-
point relay protection, such as under- and
overvoltage protection. All of this protection is
provided by two CPUs, each providing redundant
back-up to the other at all times. In addition, more
redundant overcurrent protection is provided at the
individual circuit breaker level by the Messenger
associated with each circuit.

However, the Entellisys system offers much more
than these traditional protection modes. Its ability
to simultaneously consider all the voltages, currents,
and circuit breaker conditions within the system
provides zone-based protection and optimization of
protective settings for a variety of situations. This
includes changes in the topology or number of
sources available, changes in load demand, and even
changes in factors external to the gear that are com-
municated via the Entellisys system’s Modbus over
TCP/IP interface or Discrete I/O capability.

The result is selective protection for a wide range
of fault values by delivering fast circuit interruption
when needed, while shutting down only those

circuits that absolutely must be shut down.
Maximum system reliability, lower fault energy let-
through, and lower arc flash energy can all be
achieved simultaneously. Minimum let-through
and minimum arc flash energy can be obtained
via quick settings when needed most.

This section describes the protective capabilities
provided by Entellisys. Further detail is provided
by various referenced GE publications that
describe specific functions in more detail. Setting
up and defining the exact protective levels you need
are described in the appropriate GE Entellisys
instruction book.

Traditional Overcurrent Protection

Broad range of settings

Each circuit breaker cubicle contains a set of current
transformers (CTs) that provide the current signals
for all overcurrent, relay, and metering functions.
The Entellisys system needs no additional CTs. For
circuit breaker frames rated at 2000 amperes and
above, the CTs are sized to the circuit breaker frame.
Smaller frames may have one of several CTs
as listed in Table 7.1. All protective settings for
each circuit breaker depend on the CTs in the
corresponding cubicle.

The long-time pickup for each circuit breaker is set
at the Messenger above each circuit breaker. The
rest of the protective settings for each circuit
reside in software at each of the redundant
Entellisys system central processor units (CPUs).
The settings may be adjusted via the human-
machine interface (HMI) for the system. The
exception to this is the instantaneous trip setting

Table 7.1

Current Sensors and Current Switch Settings Available for
Each CB Frame

Rating switch and CT rating is set at the Messenger.

Frame Size

Sensors

Rating Switch Values in Amperes

800

150

80,

100,

125,

150