Selecting The Braking Unit - Schneider Altivar 61/71 Guía De Explotación

Selecting the braking unit

For braking, the braking resistor is selected to match the required power and the braking cycle.
In general:
2
U
P ˆ
d
---------
=
max
R
^
Maximum braking power available with the braking unit
P
max
P Continuous thermal braking power
contin
U Braking unit control level
d
I Braking resistor thermal current (see the TH setting)
Note: The drive has a protection device inside the braking resistor. (See the Programming Manual). A thermal overload relay can also
be used.
Thermal overload relay
P = nominal braking resistor power
R = resistance value
⇒
2
P = R I I =
In the formulae, we have:
P ˆ
= Braking unit power
max
2
Pcontinuous = I R (P Resistor)
44
P
--- -
= thermal overload relay rated value
R
2
U d
P ˆ
----------
=
max
R
[W]
[W]
[V]
[A]
1757084 11/2009