Ex n UPS Systems

Our Ex n UPS system is a standard product for an application in a Zone 2 pressurised room and has an Ex nA battery unit, type SBCE-1535, combined with an Ex d battery isolation contactor enclosure and a converted industrial UPS with no batteries (invertor).

The safety philosophy of the system is as follows:

The UPS detects two shutdown conditions namely, loss of pressure shutdown (detected as loss of mains supply to the UPS) and high level gas alarm (signaled via a volt free contact in a CPFG panel).

Two timers in the UPS control the timing of the battery isolation. After shutdown the cabin has to be fully purged and pressurized in order for the UPS to be energized.

In the event of a sustained loss of pressure the Non Ex equipment in the cabin is shutdown after a preset time delay, with exception of the UPS and its load.

The UPS remains energized for the duration of an adjustable loss of pressure timer. Typical loss of pressure shutdown time 30mins.

In the event of a high level gas alarm the Non Ex equipment in the cabin is shutdown instantly, with exception of the UPS and its load.

The UPS remains energized for the duration of an adjustable high level gas alarm timer. Typical high level gas alarm shutdown time 30sec, enough to allow a computer to execute a controlled shutdown.

This product is compliant with the requirements of DNVGL-ST-E272.