Inhaltsverzeichnis
Werbung
Verfügbare Sprachen
Verfügbare Sprachen
10/10 MN03407004Z-DE/EN
Monitoring overload of
motors in the Ex e area
Adjusting the overload
current protection
j
2
Configuration
Ex e type of protection is achieved on motors by special
constructive measures. The motors are assigned according to
the highest permissible surface temperature classes. The
temperature rise time t
current and rated current I
specified on the rating plate of the motor.
The temperature rise time t
for the temperature of the motor winding to rise from its final
rated operational temperature up to the limit temperature,
at a startup current of I
However, since Ex e motors are not intrinsically safe,
explosion safety is only achieved by taking special measures
during installation and by selecting appropriate operating
conditions (PTB testing regulations), e.g. by a combination
of the circuit with a correctly rated and set overload current
protection.
Danger!
The selected current overload protection system must not
only ensure proper motor current monitoring, but also that
the seized motor is switched off within the temperature
rise time t
. This means, the protective device must be
E
rated in such a way to ensure that the tripping time t
the ratio I
/I
of the Ex e motor is not higher than its
A
N
temperature rise time t
curve, in order to safely switch off the motor within that
a
period (
following example).
and the ratio between startup
E
/I
are calculated also and
A
N
represents the time that expires
E
.
A
according to its characteristics
E
for
A
39
Quicklinks ausblenden:
Werbung
Kapitel
Inhaltsverzeichnis
