Electrical Distribution Protection
Presentation
MicroLogic B trip units are designed to provide protection against overcurrents and ground-fault currents.
Description
When choosing protection characteristics, take into account:
-
Overcurrents (overloads and short-circuits) and potential ground-fault currents
-
Conductors that need protection
-
Coordination and selectivity between the devices
-
The presence of harmonic currents
Protection characteristics can be represented on a trip curve that shows the circuit breaker trip time as a function of the measured current and protection settings. Protection settings are indexed on the rated current In of the MicroLogic B trip unit.
Rated Current In
The protection setting ranges depend on the rated current In, defined by the sensor plug inserted in the MicroLogic B trip unit.
The sensor plug can be replaced or modified. Mechanical mismatch protection prevents the installation of a sensor plug that is not compatible with the circuit breaker frame.
The range of sensor plugs available is shown in the following table.
|
In |
Commercial reference |
Frame rated current |
||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
MTZ1 |
MTZ2 |
|||||||||||||
|
06 |
08 |
10 |
12 |
16 |
08 |
10 |
12 |
16 |
20 |
25 |
32 |
40 |
||
|
400 A |
LV855114 |
✔ |
✔ |
✔ |
– |
– |
✔ |
✔ |
– |
– |
– |
– |
– |
– |
|
630 A |
LV855115 |
✔ |
✔ |
✔ |
✔ |
– |
✔ |
✔ |
✔ |
– |
– |
– |
– |
– |
|
800 A |
LV855116 |
– |
✔ |
✔ |
✔ |
✔ |
✔ |
✔ |
✔ |
✔ |
– |
– |
– |
– |
|
1,000 A |
LV855117 |
– |
– |
✔ |
✔ |
✔ |
– |
✔ |
✔ |
✔ |
✔ |
– |
– |
– |
|
1,250 A |
LV855118 |
– |
– |
– |
✔ |
✔ |
– |
– |
✔ |
✔ |
✔ |
✔ |
– |
– |
|
1,600 A |
LV855119 |
– |
– |
– |
– |
✔ |
– |
– |
– |
✔ |
✔ |
✔ |
✔ |
– |
|
2,000 A |
LV855120 |
– |
– |
– |
– |
– |
– |
– |
– |
– |
✔ |
✔ |
✔ |
✔ |
|
2,500 A |
LV855121 |
– |
– |
– |
– |
– |
– |
– |
– |
– |
– |
✔ |
✔ |
✔ |
|
3,200 A |
LV855122 |
– |
– |
– |
– |
– |
– |
– |
– |
– |
– |
– |
✔ |
✔ |
|
4,000 A |
LV855123 |
– |
– |
– |
– |
– |
– |
– |
– |
– |
– |
– |
– |
✔ |
MicroLogic 2.0 B Trip Unit
MicroLogic 2.0 B trip units provide:
-
Long-time overcurrent protection (Ir)
-
Instantaneous overcurrent protection (Isd)
The protection functions of MicroLogic 2.0 B trip units operate without an auxiliary power supply. The trip unit is powered by the current flowing through the circuit breaker.
MicroLogic 5.0 B Trip Unit
MicroLogic 5.0 B trip units provide:
-
Long-time overcurrent protection (Ir)
-
Short-time overcurrent protection (Isd)
-
Instantaneous overcurrent protection (Ii)
The protection functions of MicroLogic 5.0 B trip units operate without an auxiliary power supply. The trip unit is powered by the current flowing through the circuit breaker.
MicroLogic 6.0 B Trip Unit
MicroLogic 6.0 B trip units provide:
-
Long-time overcurrent protection (Ir)
-
Short-time overcurrent protection (Isd)
-
Instantaneous overcurrent protection (Ii)
-
Ground-fault protection (Ig)
The protection functions of MicroLogic 6.0 B trip units operate without an auxiliary power supply. The trip unit is powered by the current flowing through the circuit breaker.
DIN / DINF Instantaneous Protections
DIN / DINF instantaneous protections are internal protections used when the short-circuit current reaches the withstand limit of the circuit breaker. These protections are not adjustable and are unlikely to be triggered in normal operating conditions.