Page 237 - Uninterruptible Power Supplies

Notes on Systems Installation
Notes on Systems Installation 235

If there is a remote radiator, warm air will be discharged from it and
it will be an additional source of noise
Vibration should be considered if the generating set is within an
occupied building, steel framed buildings are particularly suscepti-
ble to noise generated by rotating sets
Leakage of fuel, fuel tanks are frequently required to be bunded
The generating set should be close to its electrical load and as close
as practicable to a supply of fuel
An expansion of generator installation guidelines can be obtained in
Chap. 1.
The chances of a prime mover failure are remote these days. For
example, in lieu of batteries we now have a flywheel design which
requires the prime mover to provide full power in approximately 12 to
15 s. Or indeed the close coupled diesel sets are able to support the sys-
tem within 2 to 3 s!
The project may require consideration of local government authority,
as regards the effect of appearance, noise, exhaust fumes, and of course
local fire regulations. Consideration will also have to be given to mains
power.
Adequate space for the system will require consideration to allow ser-
vicing of the equipment. It should be noted that in the case of most cubi-
cles (either rotary or static UPS) rear access for servicing is required.
Access to wound components such as transformers is often given a low
access priority on the supposition that failure rate of such devices is low.
Since the devices are heat generating, adequate ventilation must be
provided. For example, a static UPS rating 200 kVA will be a fan cooled
cubicle generating some 16 kW of heat at full load. The UPS itself can
work in ambient temperatures up to 40°C. However, the supporting bat-
tery, particularly those of a VRLA design, is best operated at 20 to 25°C
(68 to 77°F). When designing battery stands or enclosures ensure that
cooling air is allowed to surround the cell by allowing a gap of 10 mm
between cells. Heat build up in such enclosures can be a major defect.
Typically, an enclosure will allow a 2 degree ambient temperature rise.
The design of small UPS modules where space is at a minimum can
have a major effect on battery performance. Also, ensure that for such
small units operational staff refrain from locating the device adjacent
to a heat source such as a radiator, and that the usual warning lamp of
low battery is visible!
It is surprising how many instances we have found of the small UPS
being installed in unfavorable conditions, and then forgotten! There is
a tendency for such units to be treated as another black box, just

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