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Functions and
characteristics
Motor protection
Micrologic 2-M electronic trip units
Circuit breakers with a Micrologic 2.2 / 2.3-M trip unit include protection similar to an
inverse-time thermal relay. They are combined with a contactor.
Protection
..............................................................
Settings are made using a dial.
Overloads (or thermal protection): Long-time protection and trip class (Ir)
Inverse-time thermal protection against overloads with ad
j
ustable pick-up Ir.
Settings are made in amperes. The tripping curve for the long-time protection, which
indicates the time delay
tr
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Trip class (class)
The class is selected as a function of the normal motor starting time.
Class 5: starting time less than 5 s
b
Class 10: starting time less than 10 s
b
Class 20: starting time less than 20 s
b
For a given class, it is necessary to check that all motor-feeder components are
sized to carry the 7.2 Ir starting current without excessive temperature rise during the
time corresponding to the class.
Short-circuits: Short-time protection (Isd)
Protection with an ad
j
ustable pick-up
Isd
. There is a very short delay to let through
motor starting currents.
Short-circuits: Non-adjustable instantaneous protection (li)
Instantaneous protection with non-ad
j
ustable pick-up
Ii
.
Phase unbalance or phase loss (lunbal) ( )
This function opens the circuit breaker if a phase unbalance occurs:
WKDW LV JUHDWHU WKDQ WKH ¿[HG SLFN XS
b
Iunbal
following the non-ad
j
ustable time delay
b
tunbal
equal to:
0.7 s during starting
v
4 s during normal operation.
v
Phase loss is an extreme case of phase unbalance and leads to tripping under the
same conditions.
Indications
…………………………………………
Front indications
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b
event of a fault.
Red alarm LED for motor operation: goes ON when the thermal image of the rotor
b
and stator is greater than 95% of the permissible temperature rise.
Remote indications via SDTAM module
Compact NSX devices with a Micrologic 2 can be equipped with an SDTAM module
dedicated to motor applications for:
a contact to indicate circuit-breaker overload
b
a contact to open the contactor. In the event of a phase unbalance or overload,
b
this output is activated 400 ms before circuit-breaker tripping to open the contactor
and avoid circuit breaker tripping.
This module takes the place of the MN/MX coils and an OF contact.
Note:
all the trip units have a transparent lead-sealable cover
that protects access to the adjustment dials.
PB103376
SDTAM remote indication relay module
with its terminal block.
Micrologic 2-M trip units provide built-in
thermal and magnetic protection. They are
used in
2-device motor-feeder solutions
on Compact NSX100 to 630 circuit breakers
with performance levels B/F/H/N/S/L.
They provide protection for motors up to
315 kW at 400 V against:
b
short-circuits
b
overloads with selection of a trip class (5,
10 or 20)
b
phase unbalance.
DB112111
559E1500.indd
version: 1.0