normal electric power source may be considered. If more than one generator
is installed, automatic paralleling capability should be provided. Parallel
operation of generators with the local commercial utility supply may require
the approval of the local utility company.
4.8.3
Starting and Maintenance Considerations. Controls shall allow
delay in starting the emergency generator(s) from l0 to 120 seconds (variable
to be set by the facility) to avoid cycling of the generator(s) during
momentary transients or outages of the normal electric power supply.
Controls should also provide a test position on generators to allow them to
be run for a set period until the temperature stabilizes (usually less than
30 minutes) for maintenance purposes. This procedure should be done once
every 2 weeks.
4.8.4
Service Configuration for Small Loads. For a small installation,
it may be economically and operationally feasible to have the same emergency
electric generator supply both the UPS equipment and any other essential
auxiliary system loads.
4.8.5
Battery Charging Restrictions. Do not provide for additional
battery charging requirements when sizing the emergency generator. The UPS
is provided with an automatic control which limits the battery charging
current to 3 percent of the output rating whenever the emergency generator
is furnishing power to the UPS unit and the UPS unit is providing rated
load.
4.9
Electromagnetic Interference (EMI) Suppression. Determine the
necessity for the UPS installation to conform with the EMI suppression
requirements of MIL-STD-461, Electromagnetic Interference Characteristics,
Requirements for Equipment. UPS equipment is not furnished with EMI
suppression provisions unless the facility is located on an EMI sensitive
site. Where EMI suppression is necessary for a specific installation, all
conductors shall be installed in threaded rigid steel conduit to meet EMI
suppression requirements.
4.10
UPS Battery. The GFE battery provided is a heavy duty industrial
unit of the lead calcium type having an ampere-hour rating sufficient to
supply the direct current to the inverter as covered by the manufacturer's
installation instructions. Battery racks are also GFE. The battery is
normally furnished with two-tier racks. Battery racks shall be grounded.
Seismic racks shall be provided where required.
4.11
Remote Alarms. The UPS equipment is supplied with a GFE remote
monitor panel to be installed in the operating space served by the UPS unit
or in another continuously occupied room, such as a guard office. Since UPS
equipment rooms are usually unattended, additional remote indicating devices
shall be provided to monitor the environmental control and fire alarm system
of UPS module and battery rooms.
4.12
UPS and Battery Room Requirements. The UPS modules and associated
battery shall be installed in separate rooms. Construction should be of
permanent type. The wall separating the UPS module room from the battery
room should be fireproof (1-hour rating). It is recommended that, where
practical, space be provided in the UPS module and battery rooms for the
addition of future UPS equipment. Additional design requirements are given
in paras. 4.12.1 through 4.12.4.
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