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3.4.2 Faults during Normal Operation
The controller switches off automatically, if:
–
the mains voltage fails for longer than 2 s
–
the internal enclosure pressure falls below the set MIN value (factory setting: 0.8 mbar)
–
the internal enclosure pressure rises above the set MAX value (factory setting: 15.0 mbar)
Once the malfunction has been remedied, operation resumes automatically; if the pressure drops
below the MIN value, the purge process is repeated.
Fig. 6: Fault during normal operation
T1: The purge process has ended. The specified internal enclosure pressure (see Chapter 5
“Parametrizing the Controller“; here 2 mbar) is attained, and the units inside the EEx-p
enclosure are activated.
T2: Normal operation begins. The internal enclosure pressure (see Chapter 5 “Parametrizing the
Controller“; factory setting: 2 mbar) is regulated to the setpoint value.
T3: The internal enclosure pressure drops. If the pressure value falls below the “Switchpoint of
Minimum Pressure“(see: 5 “Parametrizing the Controller“; factory setting: 0.9 mbar) in relation
to the external pressure, the units located inside the enclosure are switched off.
T4: Renewed purge
T5: Normal operation begins
T6: The internal enclosure pressure rises. The increased internal enclosure pressure cannot
escape through the mechanical valve.
T7: If the internal pressure value exceeds the “Switchpoint of Overpressure“ (see Chapter 5
“Parametrizing the Controller“; factory setting: 15 mbar), the units located inside the enclosure
are switched off.
T8: After the pressure has been relieved, normal operation resumes without purge.