Weidmüller is a leading international provider of solutions for electrical connectivity,transmission and conditioning of power, signal and data in industrial environments.The company with headquarters in Detmold/Germany develops, produces and sellsproducts in the field of electrical connectivity and electronics all over the world.
The values are entered graph with
a system linear coordinates illustrate
the relationships between the currents,
the ambient temperatures and the
temperature rise the component. The total the
ambient temperature plus the
temperature rise caused the current
load (power loss volume resistance)
may not exceed the upper limit
temperature the component, otherwise
it will damaged even completely
ruined.
Reducing the currents 80% results in
the “derating curve” which the
maximum permissible volume resistances
and the measuring uncertainties the
temperature measurements are taken
into account such way that they are
suitable for practical applications, as
experience has shown.
Furthermore, the current-carrying
capacity influenced the geometry
of the component, the number poles
and the conductor(s) connected it.
A line drawn perpendicular the x-axis
at the upper limit temperature the
component completes the system of
coordinates.
Derating curve (current-carrying capacity curve)
Base curve
max.
The current-carrying capacity is
determined empirically according to
DIN IEC 60512-3.
The loading currents are plotted the
y-axis, the component ambient
temperatures the x-axis.
The upper limit temperature a
component the rated value determined
by the materials used.5
Technicalappendix
W
Derating curve
The derating curve shows which
currents may flow continuously and
simultaneously via all possible
connections when the component is
subjected various ambient
temperatures below its upper limit
temperature. temperature
of component
tg upper limit temperature component
tu ambient temperature
In current
Derating curve
tg upper limit temperature component
tu ambient temperature
In current
a base curve
b reduced base curve (derating curve)
Example: derating curve for minimum
and maximum number poles
Ambient temperature [°C]
LoadcurrentI[A]
.W.
The associated average values the
temperature rise the component,
∆ tb1-tu1, tb2-tu2, are plotted
for every current I1, I2, the left the
perpendicular line. this, the
resulting component temperatures
tb1, tb2 …
and the ambient temperatures tu1, tu2
are measured for three different currents
I1, I2, ….
As practically impossible choose
components with the maximum
permiss-ible volume resistances for the
measurements, the base curve must be
reduced.
The current-carrying capacity hence
not constant value, but rather
decreases the component ambient
temperature increases. the derating
curve exceeds the currents the low
ambient temperature zone, which given
by the current-carrying capacity the
conductor cross-sections be
connected, then the derating curve
should limited the smaller current in
this zone.
The points generated this way are
joined form roughly parabolic curve
