Inhaltsverzeichnis
Werbung
Verfügbare Sprachen
Verfügbare Sprachen
2 Engineering
2.1 Overload monitoring of motors in the Ex e area
2.2 Setup of the overcurrent protection system
The Ex e protection of motors is achieved by means of special design
measures. The motors are assigned to temperature classes on the basis of
the highest permissible surface temperatures. In addition, temperature rise
time t
and the ratio I
E
current I
are also determined and specified on the motor.
N
The temperature rise time t
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, Ex e motors are not safe on their own. Explosion safety can only
be achieved by taking additional measures during installation and by
selecting appropriate operational conditions (PTB testing regulations), e.g. by
adding a correctly rated and set overload protection to the circuit.
DANGER
The selected overload protection system must not only ensure
proper monitoring of the motor current, but also that the seized
motor is switched off within the temperature rise time t
In other words:
The protective device must be rated in such a way so as to
ensure that the tripping time t
motor is not higher than its temperature rise time t
to its characteristics curve, in order to safely switch off the
motor within that period (a following example).
ZE/XTOM 11/17 MN03407003Z-DE/EN www.eaton.com
2.1 Overload monitoring of motors in the Ex e area
/I
of the starting current I
A
N
represents the time that expires for the
E
A
2 Engineering
to the rated operational
A
for the ratio I
/I
of the Ex e
A
N
E
.
A
.
E
according
31
Quicklinks ausblenden:
Werbung
Kapitel
Inhaltsverzeichnis
