Page 400 - Sustainable On-Site CHP Systems Design, Construction, and Operations

Governmental Facility—Mission Critical 373

most rigorous performance requirement is for a gen-set power to be available for emer-
gency egress lighting within 10-seconds and run for 90-minutes; a requirement that is
sometimes met with a static reserve such as a battery. Other life safety infrastructure
such as fire pumps, elevators, and fire alarm systems demand more from the prime
mover. As long as life safety requirements are met, the NEC permits the same prime
mover(s) to be used to supply backup power to other optional standby loads.
An idealized emergency management district electric system, with renewable dis-
tributed resources and load classes integrated with CHP, is shown in Fig. 23-2. Require-
ments for the complex SCADA, signaling and control systems are not shown here but
guidance on them appears in Annex G of the 2008 NEC. Additionally, Fig. 23-2 provides
a concept diagram for CHP in an emergency management facility: New National Elec-
tric Code Article 708—Critical Operations Power Systems requires that emergency
management facilities tool up for 100 percent loss of utility supply. Per 708.20(F)(3) a

(Macro Utility)
Local Renewable
Electric
Grid Power Source
NEC Article 703
Normal
Interactive
Switchgear Building Loads
Radiator/
Recuperator
Critical
Operation
Power
Macro-Micro Grid NEC Article 708
Steam or Interconnect
Hot Water Switchgear Legally Required
Power
NEC Article 701
Emergency
Transfer Distribution Power
N+X
Generators Switchgear Switchgear NEC Article 700
Redundant power
Critical Scada &
chain architectures
to mitigate single UPS System Communication
points of failure NEC Article 708
Heat
Exchanger
Critical
Computer
Cooling
Absorption Loads
NEC Article 702
Chiller

Chilled Water

Thermal Grid

FIGURE 23-2 Concept diagram for CHP in an emergency management facility.