WEG W22 Premium E3 Manual De Instalación, Operación Y Mantenimiento página 70

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EPL Da: equipment for explosive dust atmospheres, having a "very high" level of protection, which is not a
g
source of ignition in normal operation, during expected malfunctions, or during rare malfunctions.
EPL Db: equipment for explosive dust atmospheres, having a "high" level of protection, which is not a source
g
of ignition in normal operation or during expected malfunctions
EPL Dc: equipment for explosive dust atmospheres, having a "enhanced" level of protection, which is not a
g
source of ignition in normal operation and which may have some additional protection to ensure that it
remains inactive as an ignition source in the case of regular expected occurrences ( for example failure of a
lamp).
EPL Ma: equipment for installation in a mine susceptible to firedamp, having a "very high" level of protection,
g
which has sufficient security that it is unlikely to become an ignition source in normal operation, during
expected malfunctions or during rare malfunctions, even when left energized in the presence of an outbreak
of gas.
EPL Mb: equipment for installation in a mine susceptible to firedamp, having a "high" level of protection, which
g
has sufficient security that it is unlikely to become an source of ignition in normal operation or during expected
malfunctions in the time span between there being an outbreak of gas and the equipment being de-
energized.
[IEC 60079-0 item 3.18]
Time "t ": time taken for an a.c. rotor or stator winding, when carrying the initial starting current I
E
up to the limiting temperature from the temperature reached in rated service at the maximum ambient
temperature. See Figure 1-1.
Symbols
θ - temperature
A – maximum allowed ambient temperature
B – service temperature
C – limiting temperature
t - time
1 – temperature rise in rated service
2 – Temperature rise during locked rotor test
70 Manual of Electric Motors
Figure 1.1: Time "t "
E
, to be heated
A