Capstone Turbine Corporation
Model C65 Hybrid UPS User’s Manual
400027 Rev A (July 2010)
Page
19 of 66
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.
Engine Control Module (ECM)
The ECM connects the high speed turbine generator output to the internal 760V DC bus. It
is bi-directional, and power is taken from the DC bus to start the turbine. During operation,
the turbine generator speed is independent from the utility input or load output
frequencies. The ECM includes all the logic for operating the turbine generator, as well as
resistive energy dissipation capability to absorb turbine power in case of sudden load loss.
Turbine Generator
The Capstone turbine generator uses fuel input to create useful high-frequency AC
electrical output, which is converted by the ECM to DC for distribution to the remainder of
the Hybrid UPS system. Power from the turbine is used for the critical load output, with
any excess going back through the GLCM to the utility grid and/or through the BCM to
recharge the batteries.
Transfer Switch
Typically, a transfer switch or other load transfer scheme will be supplied by others to
allow power to be fed to the critical loads directly by the Utility bus in case there is a
problem with the Hybrid UPS system. Since the Hybrid UPS system will always try to
maintain synchronism of its load output to the utility input, a closed transition transfer
switch scheme can be used to minimize voltage disturbances to the critical loads.
UPS Mode
The Hybrid UPS MicroTurbine can take power from a utility grid and make it available to
the critical loads through a double power conversion process, similar to the way a
traditional UPS operates. The output power to the critical loads is isolated from
disturbances on the utility grid, and its power quality is maintained. In UPS Mode, the
turbine generator is not operating, and the output power is supplied only by the utility grid
input from the GLCM through to the LLCM. The frequency of the output to the critical load
is determined by the utility grid, and the phase relationship is maintained between input
and output of the Hybrid UPS system. The desired voltage to the critical load is pre-set by
the user, and the Hybrid UPS system will attempt to maintain this pre-set value even if
utility voltage varies.
High Efficiency Mode
The High Efficiency Mode of operation allows the microturbine to generate its’ own power
to supplement the utility grid. The power it generates can be set at more or less than the
amount of power the critical loads require, with the utility grid connection automatically
taking or giving the difference as required. The system must be actively connected to a
stable utility grid source for it to enter the High Efficiency Mode. High Efficiency Mode can
therefore be thought of as a special case of UPS Mode, where the turbine has been
commanded ON and operates in parallel with the Utility grid.
