MicroLogic 2 M Electronic Trip Unit
Introduction
The MicroLogic 2 M electronic trip unit is suitable for protecting motor-feeders on standard applications. The thermal trip curves are calculated for self-ventilated motors.
The MicroLogic 2 M electronic trip unit can be used to create a type 1 or type 2 coordination motor-feeder.
Description
The adjustment dials and indications are on the front face.
A MicroLogic 2.2 M/2.3 M electronic trip unit setting range
B Adjustment dial for the long-time protection pickup Ir
C Selection dial for the long-time protection time delay class
D Adjustment dial for the short-time protection pickup Isd
E Value of instantaneous protection pickup Ii
F Test port
G Phase-unbalance
H Ready LED (green)
I Alarm LED
The trip unit rating In corresponds to the maximum value of the setting range.
Setting the Long-Time Protection
The long-time protection is set by 2 dials according to the starting characteristics of the application.
-
The long-time protection pickup Ir is set using a multi-position dial.
The maximum setting value (maximum setting on adjustment dial) equals the trip unit rating value In.
The following table shows the values of the pickup Ir (in amperes) for long-time protection that are displayed directly on the dial with respect to every trip unit rating.
|
Trip unit rating In (A) |
25 |
50 |
100 |
150 |
220 |
320 |
500 |
|---|---|---|---|---|---|---|---|
|
Pickup Ir (A) |
12 |
25 |
50 |
70 |
100 |
160 |
250 |
|
14 |
30 |
60 |
80 |
120 |
180 |
280 |
|
|
16 |
32 |
70 |
90 |
140 |
200 |
320 |
|
|
18 |
36 |
75 |
100 |
155 |
220 |
350 |
|
|
20 |
40 |
80 |
110 |
170 |
240 |
380 |
|
|
22 |
42 |
85 |
120 |
185 |
260 |
400 |
|
|
23 |
45 |
90 |
130 |
200 |
280 |
440 |
|
|
24 |
47 |
95 |
140 |
210 |
300 |
470 |
|
|
25 |
50 |
100 |
150 |
220 |
320 |
500 |
-
The long-time protection time delay class is set by using a multi-position dial: the choice of class is 5, 10 and 20.
The following table shows the value of the trip time delay depending on the current in the load for all 3 classes:
|
Current in the load |
Class |
||
|---|---|---|---|
|
5 |
10 |
20 |
|
|
Trip time delay tr (in seconds) |
|||
|
1.5 x Ir |
120 |
240 |
400 |
|
6 x Ir |
6.5 |
13.5 |
26 |
|
7.2 x Ir |
5 |
10 |
20 |
The precision range is - 20%, + 0%.
Setting the Short-Time Protection
The pickup for short-time protection is set by using a multi-position dial. It is displayed in multiples of Ir
|
Step |
Action |
|---|---|
|
1 |
Set the long-time protection first: the setting pickup is Ir (A). |
|
2 |
Turn the Isd adjustment dial to the value required (the setting range is: 5 to 13 x Ir in steps of Ir (9 settings)). |
|
3 |
Isd is set to Ir (A) x Isd setting. |
The precision range is +/- 15%.
The short-time protection time delay cannot be adjusted: 30 ms.
Setting the Instantaneous Protection
The following table shows the pickup Ii values (in amperes) according to the trip unit rating In.
|
Trip unit rating In (A) |
|||||||
|---|---|---|---|---|---|---|---|
|
25 |
50 |
100 |
150 |
220 |
320 |
500 |
|
|
Pickup Ii (A) |
425 |
750 |
1500 |
2250 |
3300 |
4800 |
7500 |
The precision range is +/- 15%.
Phase-Unbalance Protection
MicroLogic 2 M trip units incorporate a protection against phase-unbalance. The characteristics are:
-
Protection not adjustable
-
Pickup: 30% phase-unbalance (the precision range is +/- 20%)
-
Overshoot time: 4 s in steady state, 0.7 s during startup
Example: A phase-unbalance exceeding 30% for longer than 4 s in steady state causes the protection to trip.
Contactor Opening Command
Trip units fitted with an SDTAM module can use output 2 (SD4) from this module to activate the contactor opening command for the motor-feeder before the circuit breaker trips.
Example of Application
Protection of a motor-feeder with the following characteristics:
-
Power supplied by a 1,250 kVA transformer - 400 V, 4%
-
Protection of a motor application defined by:
-
2-component motor-feeder (circuit breaker, contactor)
-
Direct-on-line starting
-
Motor power 110 kW, that is, In = 196 A
-
Type 2 coordination
-
The application constraints dictate a slow startup
-
Installation diagram
Calculations performed on the installation in accordance with the regulations have determined the characteristics of the appropriate ComPact NSX to install (calculations performed using the Ecostruxure Power Design – Ecodial software).
Installation diagram
|
Installation |
Chosen ComPact NSX |
Comments |
|---|---|---|
|
In = 196 A |
ComPact NSX250 MicroLogic 2.2 M 220 |
Motor circuit breaker, case size |
|
Isc = 28.5 kA |
F |
Icu performance can be read from rating plate |
|
Ik min = 14.8 kA |
– |
– |
Trip unit protection settings
|
Installation |
Trip unit setting |
Comments |
|---|---|---|
|
In = 196 A |
MicroLogic 2.2 M 220 set to 200 A |
MicroLogic trip unit setting |
|
Slow starting |
Set in class 20 |
Long-time protection trip class |
|
Ik min = 14.8 kA Transient = 14 In |
Isd/In > 12 or Isd > 2,400 A |
Isd protection setting compatible with:
|