Trip classes
The 3RB24 solid-state overload relay for IO‑Link is suitable for normal starting conditions and
heavy starting conditions. Depending on the prevailing starting condition, the required trip class
CLASS 5, CLASS 10, CLASS 20 or CLASS 30 can be set using a rotary switch.
Note
The set trip class can be read out via IO‑Link for documentation purposes, for example.
Tripping characteristics
The tripping characteristics map the relationship between tripping time and tripping current as
a multiple of the rated operational current I
e
; they are specified for symmetrical 3-pole loading
and 2-pole loading from cold.
Minimum tripping current
The lowest current at which tripping will occur is known as the minimum tripping current.
According to IEC 60947‑4‑1, the minimum tripping current must be within defined limits. In the
case of the 3RB24 solid-state overload relay, the limits for the minimum tripping current with
symmetrical 3-pole loading are between 105 and 120% of the rated operational current.
Tripping times
The minimum tripping current determines the progression of the tripping characteristic up to
higher tripping currents based on the characteristics of the trip classes. The trip classes describe
time intervals within which the solid-state overload relays for IO-Link have to trip in the case of
a symmetrical, 3-pole load from the cold state with 7.2 times the rated operational current I
e
.
The tripping times according to IEC/EN 60947‑4‑1, tolerance band E, are shown in the table
below.
Table 10-1
Tripping times
Trip class
Tripping time
CLASS 5
3 ... 5 s
CLASS 10
5 ... 10 s
CLASS 20
10 ... 20 s
CLASS 30
20 ... 30 s
Operation
10.1 Setting the current (rated operational current) and trip class
SIRIUS 3RB24 electronic overload relay for IO-Link
Equipment Manual, 07/2022, NEB969165602000/RS-AA/003
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