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Section 6. EntelliGuard Messenger
directly into a Messenger's A/D converter via the
Test Port connector. The test kit can change the
waveform characteristics of the sinusoidal signals
to test the different overcurrent and protective
relay functions for each circuit breaker.
Sealable Cover
A hinged, clear Lexan cover is installed over the
LEDs, switches, and Test Port. The cover includes
provisions for wire seals so that the current setting
and long time pick-up selections can sealed to
meet the requirements of NEC for restricted
access to the trip setting adjustments.
Self-Powered Mode
The Messenger is normally powered from the
switchgear redundant control power buses with
dual UPS back-up. In this operating mode, the
Messenger passes digital signals of the currents and
voltages to the dual CPUs and, in turn, receives and
executes instructions from the CPUs if the currents
and/or voltages require a breaker operation.
The Messenger provides overcurrent protection for
the circuit in the event all control power is lost
(loss of both control power sources and both
back-up UPSs) or both redundant communication
networks or redundant CPUs become unavailable.
The Messenger's self-powered mode utilizes power
from the cubicle-mounted current sensors to
power its internal circuits. When running in self-
powered mode, the overcurrent protection curves
built in to the Messenger utilize the maximum
pick-up and delay settings for each applicable
overcurrent function (overload, short circuit, and
ground fault). Using the maximum pick-up and
delay settings insures the self-powered overcurrent
characteristics in the Messenger will not interfere
Table 6.1
Current Sensor Values and Associated Current Settings
Current Sensor
Current Setting
Current Sensor
Rating (Amps)
(Amps)
Rating (Amps)
80
100
150
125
150
150
200
225
400
250
300
400
26
Current Setting
Current Sensor
(Amps)
Rating (Amps)
300
400
450
800
500
2000
600
700
800
600
800
1000
1600
1100
3200
1200
1600
with the programmed settings running in the CPUs.
Compared to traditional low voltage circuit protection,
the self-powered mode is similar to having a
back-up integral trip unit on a circuit breaker that
is programmed with all overcurrent characteristics
set at their maximum values.
i-Button
A factory-programmed memory device called
the "i-Button" provides the unique protection
characteristics for each breaker cubicle in the
switchgear line-up. Characteristics include the
breaker frame size, the installed current sensor
rating, and the overcurrent characteristics for
the circuit. The i-Button programming determines
the upper and lower limits for the overcurrent
protection settings and the type of ground fault
protection (none, standard, or switchable).
The i-Button and holder are tethered to the breaker
cubicle and communicate with the Messenger via
a slot in the side of the Messenger. Now, the unique
characteristics of a given circuit are captured in
the i-Button, which becomes a part of the breaker
cubicle and therefore a part of the connected load.
The i-Button – Messenger – EntelliGuard breaker
concept of Entellisys simplifies the task of determining
component interchangeability and the quantity and
type of spare parts to have on hand. All EntelliGuard
Messengers are identical; therefore, only one catalog
number is required for spare parts stocking. All
EntelliGuard breakers for a given frame size and
function are identical, thus requiring fewer spare
breakers for the range of loads in a plant. Component
interchangeability and reduced spare parts is one
of the recognizable benefits of the Entellisys concept.
Current Setting
Current Sensor
Current Setting
(Amps)
Rating (Amps)
750
800
1000
1200
4000
1500
1600
2000
1200
1600
5000
2000
2400
2500
3000
3200
(Amps)
1600
2000
2500
3000
3200
3600
4000
3200
4000
5000
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