3RU11, 3RB10, and 3RB12 overload relays
SIRIUS System Manual
GWA 4NEB 430 0999-02b
4-29
4.5.2 Connection
3RU11
The 3RU11 overload relays are equipped with the following terminal system:
• S00 to S3: Screw-type terminal for the main and auxiliary connecting
leads
• S00: Cage Clamp terminal for the main and auxiliary connecting leads
(only stand-alone installation possible)
• S0 to S3: Screw-type terminal for main contacts and Cage Clamp terminal
for auxiliary connecting leads (contactor mounting and stand-alone instal-
lation possible)
3RB10/3RB12
The 3RB10 and 3RB12 electronic overload relays have screw-type terminals.
The 3RB1246 electronic overload relays are equipped with a bar-type trans-
former.
Bar-type system
In the case of the 3RB1246 electronic overload relays with current setting
ranges < 100 A (70 mm width), the main lines are connected in a bar-type
system. The main lines are connected through the current transformer inte-
grated in the housing at rated currents for the motor of 1.25 A to 100 A.
The advantages are:
• No additional installation costs
• No power loss at the transfer resistors of the clamping units that would
otherwise be necessary
Looping through
At motor rated currents
I
N
< 1.25 A, the motor supply leads can be fed
through the loop-through openings several times (n times) in each phase.
The set current
I
e
of the device is calculated as follows:
I
e
= 3 x
I
N
Example:
I
N
= 0.5 A
n = 3
I
e
= 3 x 0.5 A = 1.5 A
n = 5 is recommended as a good upper limit in practice.
The following graphics illustrate the loop-through system:
Figure 4-23: Loop-through system, 3RB1246
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