GE Industrial Solutions WavePro Low-Voltage Power Circuit Breakers - Manual (Page 12)

MicroVersaTrip Plus™ and MicroVersaTrip PM™ Trip Units
Chapter 1. Introduction
4
1-5 Equipment Interfaces
MicroVersaTrip Plus Trip Units
MicroVersaTrip Plus Trip Units do not usually require
connections within the equipment, since all wiring is con-
tained within the circuit breaker. The only two connec-
tions are for optional zone-selective interlock (Z1 and Z2)
and the neutral sensor. Connections are made through
the breaker’s secondary disconnect A.
Zone-selective interlocking coordinates breakers, so that
the downstream breaker is allowed the first opportunity to
clear a disturbance. The two types of available zone-selec-
tive interlocking are Z1, which reacts only to ground faults,
and Z2, which reacts to both ground faults and short-time
overcurrent pickups. Separately mounted zone-selective
interlock modules are required between upstream and
downstream breakers.
Neutral Current Sensors
CAUTION: Neutral current sensors are required for
single-phase, three-wire and three-phase, four-wire sys-
tems. When the Trip Unit is connected to a three-phase,
three-wire system, the neutral sensor terminals of the
breaker are left open. Do not short any neutral current
sensor terminals in a three-phase, three-wire system, as
this could result in damage to, or malfunction of, the
electrical system.
ATTENTION: Un transformateur de courant de neutre est
nécessaire pour les réseaux 3 phases + neutre. Si le neutre
n’est pas distribué, les bornes de neutre du déclencheur
doivent être laissées ouvertes. Ne pas les court-circuiter
(ceci peut endommager le déclencheur et entrainer un
mauvais fonctionnement du système électrique.
MicroVersaTrip PM Trip Units
In addition to the inputs received by MicroVersaTrip Plus
Trip Units, MicroVersaTrip PM Trip Units also receive
inputs from external voltage conditioners, a +24 Vdc auxil-
iary power supply, and communication connections.
External +24 Vdc auxiliary power is required for operation.
POWER LEADER™ Communication Network
MicroVersaTrip PM Trip Units may be integrated into a
Power Management Control System through the POWER
LEADER™ Modbus Concentrator, which collects data
from a MicroVersaTrip PM Trip Unit (a commnet device)
and communicates across the RS485 network to a remote
PC. Also, MicroVersaTrip PM Trip Units can be wired to a
POWER LEADER Modbus Monitor through a Modbus
Concentrator. The Modbus Monitor, which is mounted
either in the equipment or independently, provides a cen-
tral station for viewing metering and status information
collected from multiple remote power management
devices.
Commnet connections are made directly to wiring termi-
nations on breaker frames. All commnet connections to
the Trip Units are made through the 50-pin plug on the
Trip Unit, which mates with a receptacle on the breaker
frame. These additional connections are made to the
equipment through the secondary disconnects of the
breaker.
Voltage Inputs
Voltage inputs are sensed by conventional instrument
potential transformers(PTs). PTs have 120 Vac secon-
daries and must always be used in groups of three; no
open-delta connections are permitted. PT primaries are
connected either line-to-line or line-to-neutral, as required.
PTs may be used for other monitoring functions, subject to
reasonable burden limitations. Note that PTs must be
connected in a specific sequence to ensure proper phase
relations and power-flow sensing.
Each PT output feeds an individual voltage conditioner
that scales the nominal voltage to approximately 1.76 Vac
for use by the Trip Unit.
Power Requirements
A small amount of power is necessary to energize the liquid
crystal display (LCD) during setup, for viewing breaker
status, and for metering displays. MicroVersaTrip PM Trip
Units require external +24 Vdc auxiliary power for proper
operation. The four sources of such power are the
following:
• Flow of current -- Breaker current sensors provide suffi-
cient power to energize the LCD when at least 20% of
the sensor’s ampere rating is flowing.
• +24 Vdc Auxilliary Power – Breakers with MicroVersa-
Trip PM Trip Units are supplied with external +24
Vdc power that, whenever present, energizes the
LCD.
• Internal Battery Power – The Trip Unit has an internal
battery that powers the unit temporarily when the
BATTERY key on the display is pressed. Battery power
automatically turns off 30 seconds after the last key-
pad press. The battery power supply is disabled when
any current is sensed through the current sensors.
• MicroVersaTrip Portable Power Pack -- The
MicroVersaTrip Portable Power Pack contains a dc