Operating Instructions
SILAS
Controller for Zones 2 and 22
Version 2.00
Page 9 of 28
SILAS_E_110806.doc Operating Instructions for the SILAS Controller
•
Technical data are subject to change
After the end of the purging time, the operating phase is initiated by the following measures:
•
The purge valve closes and the leakage losses are compensated by means of the integrated leakage air
valve.
•
The “K 2” LED lights up.
•
The K 2 relay energises. K 3 Relay switches depending on the configuration.
•
The remaining purging display goes out and the pressure inside the enclosure is displayed.
If the internal pressure during the operating phase drops below the switching „P 2” value, e.g.: due to increased leakages
during the operation, K1 relay connects the purging-air nozzle for a short time.
If the internal pressure during the operating phase drops below the switching value of “P 1”, e.g.: due to the doors being
opened, the K 3 relay energises with about 5 sec. time delay and in this way signalises that there is a drop in pressure. At
the same time, the purging-air nozzle in the purge valves is switched off to prevent purge gas flowing in when the door is
opened. If the door is closed and the internal pressure rises above the value of “P1”, the purging-air nozzle closes again
until the internal pressure reaches the “P 2” value.
If the internal pressure during the operating phase exceeds the ”P 4” switching value, the K 2 relay switches off for the
duration of the increased overpressure.
5.2
Use in Ex zone 22
In applications in the Ex zone 22 it is essential to clean the control panel inside thoroughly in order to remove dust deposits
before the overpressure-monitored control panel is switched on for the first time. A pre-purging cycle functioning in the same
way as for the application in zone 2 is not suitable for this purpose.
During the operating phase the penetration of dust is prevented by the constant overpressure with relation to the ambient
atmosphere. The internal pressure is monitored by the
SILAS
Controller's
pressure control
.
To produce overpressure in the control panel greater than the switching value of “P 1”, the pressure reducer with connected
leakage needle valve is connected directly to the control panel. To prevent overpressure greater than the permissible “P 4”
switching value, the type 17-51P3-1604 pressure control device is used as an overpressure control device.
The system starts automatically once the
SILAS
Controller
, the pressure control device and the purge valve have been
assembled at the control panel and the mains voltage and purge gas have been connected. The system then monitors the
enclosure’s internal pressure during the operating phase.
If the internal pressure inside the control panel rises above the switching value of “P 1”, the K 2 relay energises.
If the internal pressure during the operating phase drops below the switching value of “P 1”, e.g.: when the door is opened,
K 2 relay switches with approx. 5 sec. time delay. If the internal pressure during the operating phase exceeds the “P 4”
switching value, the K 2 relay switches off for the duration of the increased overpressure.
