Capstone Turbine Corporation
Model C65 Hybrid UPS User’s Manual
Page
22 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.
Utility Voltage
Utility voltage must be present and within the GLCM’s utility input protective relay settings
to allow the system to operate in UPS Mode or High Efficiency Mode. Conversely, loss of
stable utility voltage will automatically trigger the GLCM to disconnect utility power and
force the Hybrid UPS system into Emergency Mode.
Utility Reconnect Delay
Once the Hybrid UPS system has been disconnected from the utility for any reason, it
must go through a reconnect sequence whenever the turbine is running or has already
entered a start sequence. This is a requirement of IEEE 1547, UL 1741, and most electric
utilities, and is intended to prevent inadvertent energizing of an unstable utility grid. The
system must wait for the utility voltage to remain within the protective relay settings for the
set reconnect delay time (5 to 30 minutes) before the Hybrid UPS system can close its
internal power connection to the utility grid. The GLCM is constantly monitoring the utility
voltage whenever it is not in Standby Mode, and will start the reconnect delay timer
whenever it senses stable conditions. Therefore, there may or may not be a state
transition delay in connecting to utility power, depending on the timing of events leading up
to the Hybrid UPS system attempting to reconnect to the utility grid.
UPS Mode vs High Efficiency Mode
If the system in enabled in UPS Mode, it will not try to start the turbine unless there is
some other reason to do so (like low battery state of charge). If the system is enabled in
High Efficiency Mode, it will always try to run the turbine unless there is some reason it
cannot (such as lack of fuel). Therefore, the selected mode of operation will have an
impact on what states the system transitions through to get to the desired mode.
Turbine Start Delay Timer
The Hybrid UPS systems include a turbine generator start delay timer to prevent systems
operating in UPS Mode from immediately starting their engines for every utility disturbance
condition. The timer is user adjustable from 0 to 10 minutes, during which time the system
waits for return of stable utility voltage. If utility voltage returns to a stable condition before
the end of this time, the turbine generator will not be started and the GLCM will
immediately reconnect utility power. If utility voltage does not return to within the
programmed GLCM protective relay limits before the end of this time, the turbine
generator will be started. Once the turbine start command has been issued, the system
must wait for utility voltage to return, and then pass through the utility reconnect delay
sequence before reconnecting utility power to the GLCM. The system will then issue a
stop command to the turbine generator once battery state of charge is above a preset
level.
