Capstone Turbine Corporation
Model C65 Hybrid UPS User’s Manual
Page
20 of 66
400027 Rev A (July 2010)
Capstone reserves the right to change or modify, without notice, the design, specifications, and/or contents of this document without
incurring any obligation either with respect to equipment previously sold or in the process of construction.
Emergency Mode
The Hybrid UPS system will automatically transition to the Emergency Mode if
commanded to operate in either UPS Mode or High Efficiency Mode and utility power is
unavailable. Emergency Mode cannot be selected as a desired operating state. In
Emergency Mode, power is supplied to the critical load from either the external batteries
and/or the turbine generator. An external battery energy source must be available for the
system to operate in Emergency Mode.
Standby Mode
In Standby Mode, the Hybrid UPS system is completely taken out of service and shut
down. No power is taken from the utility grid, or provided to the load output, and the
turbine generator is off. If left in this state for an extended period of time, the system will
also attempt to preserve energy storage life by entering a sleep mode to reduce power
requirements, and the Display Panel will go dark. This is the condition the Hybrid UPS
system will be in when shipped from the factory.
States versus Operating Modes
In the Hybrid UPS system, there are both Systems States as well as Engine States, which
together determine the Mode of Operation. Figure 3 provides an overview of the general
flow of System and Engine States from one commanded Operating Mode to another.
Transition States
The user can command the Hybrid UPS microturbines to be in UPS Mode, High Efficiency
Mode, or Standby Mode. However, there are certain required conditions for the system to
enter any of these operating modes, and it will transition through multiple states in order to
reach the desired operating mode. Emergency Mode is not a user-commanded operating
state, but rather is the result of the system being commanded to operate in UPS Mode or
High Efficiency Mode when the utility grid is unavailable.
Elements Impacting Transitions
The major elements that impact these transitions between states are:
Battery SOC
If the battery state of charge is below some preset limit (for example 50% SOC), the
turbine may need to be started to allow transition into the next operating state. This is
because the Hybrid UPS system should always be capable of continuing to power the
critical load once it starts to provide power. If the battery SOC is too low, there may not be
sufficient energy to maintain power in Emergency Mode should the utility suddenly
become unavailable.
For Hybrid UPS systems with external battery systems provided by others, the Capstone
UPS Controller must receive ongoing state of charge information. The UPS Controller will
then assure the proper transition sequence. Consult Capstone for how their individual
battery packs will provide this SOC information to the Hybrid UPS systems.
