TM-D Thermal-Magnetic Trip Unit for 3P and 4P Circuit Breakers from 80 A to 250 A
Introduction
The TM-D thermal-magnetic trip unit is designed to protect conductors in commercial and industrial electrical distribution.
The trip unit exists in two configurations:
-
3P, 3D
-
4P, 3D
Description
Setting the Thermal Protection
The thermal protection pickup Ir is set by a 4-setting dial.
Turning the thermal protection adjustment dial (A) modifies the trip curve as shown (B).
The following table shows the values of the pickup Ir (in amperes) for thermal protection (values indicated on the dial) with respect to every trip unit rating, relative to the position of the dial Ir.
|
Trip unit rating In (A) |
16 |
25 |
32 |
40 |
50 |
63 |
80 |
100 |
125 |
160 |
200 |
250 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Pickup Ir (A) |
11 |
18 |
22 |
28 |
35 |
44 |
56 |
70 |
88 |
112 |
140 |
175 |
|
13 |
20 |
26 |
32 |
40 |
50 |
64 |
80 |
100 |
128 |
160 |
200 |
|
|
14 |
23 |
29 |
36 |
45 |
57 |
72 |
90 |
113 |
144 |
180 |
225 |
|
|
16 |
25 |
32 |
40 |
50 |
63 |
80 |
100 |
125 |
160 |
200 |
250 |
Setting the Magnetic Protection on Trip Units with In from 80 A to 160 A
For trip units rated below 200 A, the magnetic protection pickup cannot be adjusted and equals the value shown below:
|
Trip unit rating In (A) |
16 |
25 |
32 |
40 |
50 |
63 |
80 |
100 |
125 |
160 |
|---|---|---|---|---|---|---|---|---|---|---|
|
Pickup Ii (A) +/- 20% |
190 |
300 |
400 |
500 |
500 |
500 |
640 |
800 |
1250 |
1250 |
Setting the Magnetic Protection on Trip Units with In from 200 A to 250 A
For trip units rated between 200 A and 250 A, the magnetic protection pickup Ii is set using a 6-setting dial.
Turning the magnetic protection adjustment dial (A) modifies the trip curve as shown (B).
The following table shows the values of the pickup Ii (in amperes) for magnetic protection (values indicated on the dial), relative to the position of the Ii dial:
|
Trip unit rating In (A) |
200 |
250 |
|---|---|---|
|
Pickup Ii (A) +/- 20% |
1000 |
1250 |
|
1200 |
1500 |
|
|
1400 |
1750 |
|
|
1600 |
2000 |
|
|
1800 |
2250 |
|
|
2000 |
2500 |
Example of Application
Protection of a feed with the following characteristics:
-
Power supplied by a 1,250 kVA transformer - 400 V, 4%
-
Protection of a distribution box located 15 m away, the loads on which are mainly for lighting (incandescent bulbs), heating, and small machines
The value of the calculated rated current (load consumption) is In = 175 A.
The following illustration shows the installation diagram:
Calculations performed on the installation in accordance with the regulations can be used to determine the characteristics of the appropriate ComPact NSX circuit breaker to install (calculations performed using the Ecostruxure Power Design – Ecodial software).
The following table presents the circuit breaker selection:
|
Installation |
Chosen ComPact NSX |
Comments |
|---|---|---|
|
In = 175 A |
ComPact NSX250 |
Determination of case size |
|
Distributed neutral |
4P, 3D |
Full neutral and linear loads |
|
Isc = 28.5 kA |
F |
Icu performance can be read from rating plate |
|
Ikmin = 14.0 kA |
– |
– |
The following table shows the trip unit protection settings:
|
Installation |
Chosen trip unit |
Comments |
|---|---|---|
|
In = 175 A |
TM-D 200, Ir set to 180 A |
Optimizing the choice |
|
TM-D 250, Ir set to 175 A |
Necessary if extensions envisaged |
|
|
Ikmin = 14.0 kA |
Ii = 2,000 A or 2,500 A |
Natural adjustment to the Ii protection for distribution, compatible with:
|