VESDA-E STX Power Supply Unit

Summary

VESDA-E power supply units are uniquely designed to complement the style and appearance of VESDA-E aspirating smoke
detectors (ASD) and are technically matched to provide sufficient current and battery charging capacity to meet the requirement of EN 54-4.

The STX variants are VdS approved and CE marked to EN54-4 so are particularly suitable for use in territories where these approvals are required. They may also be suitable in territories where ISO 7240-4 is required.

Style STX product range

Designed with the same width, colour and styling of the VESDA-E detectors, the power supplies visually blend with the VESDA-E detectors. They feature the same curved profile and also incoproate an internal channel which accommodates the exhaust of the VESDA-E detectors. This is particularly useful when it is necessary to run the exhaust pipe back to the protected area (back-venting).

There are two colours. Matt black is standard and matches the finish of the black plastic VESDA-E detectors (the “–P” variants). Alternatively the unit can be supplied with grey (RAL 7047) cover which compliments the extruded aluminium finish of the premium VESDA-E detectors.

VPS-220-STX & VPS-220-STX-SLV: 0.5 A load / 14 Ah batteries (max)

This is the shallower unit within the range with a depth and width matching the VESDA-E detectors.

Internally is an EN54-4 approved Power Supply rated to provide a 0.5 Amp continuous 24 VDC supply while also charging the batteries (not supplied) which can be a 7, 12 or uniquely, 14 amp/hr arrangement. The unit is therefore able to power the VESDA-E VEP range of detectors for over 24 hours and may also be used to power VESDA-E VEU detectors running upto fan speed 6 for similar periods.

VPS-250-STX & VPS-250-STX-SLV: 2 A load / 24 Ah batteries (max)

This is the deeper unit designed for installation with a VESDA-E VEU detector running at fan speeds upto 10. The internal charger is EN54-4 approved and is rated to provide a 2 Amp continuous 24 VDC supply. There is space for up to 24 Ah batteries (not provided).

Technical highlights

Style STX power supplies can be operated on batteries alone which is very useful for initial commissioning of Xtralis detectors as mains power is often unavailable at this time.

Style STX power supplies perform full impedance checking of the batteries to ensure that the batteries are in good condition.

Style STX units disconnect the load (i.e. power down the Xtralis detector) after a prolonged period of mains failure (>24 hours) to prevent permanent damage to the batteries.

Style STX units use a tiny current (< 3 mA) to monitor for restoration of mains power after disconnecting the load to protect the batteries (see point above) – thus ensuring that the batteries are unlikely to suffer a damaging deep discharge as long as the fault is attended to within a week.

Installation arrangements

Both units provide cable entry knockouts which line up with the VESDA-E enclosure allowing positioning of the power supply immediately below the VESDA-E detector. The PSU may also be installed above an inverted VESDA-E detector as illustrated opposite.

The front cover supports 2 LEDs giving a quick visual indication of OK and fault condition. A change over fault relay is
provided which may be monitored using the General Purpose Input (GPI) of the VESDA-E detector or directly by the fire alarm system panel using a suitable relay input.