Capstone Turbine Corporation
Model C65 Hybrid UPS User’s Manual
Page
24 of 66
400027 Rev A (July 2010)
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incurring any obligation either with respect to equipment previously sold or in the process of construction.
Transitions to/from Emergency Mode
Once the system is operating, loss of utility power will automatically transition the system
into Emergency Mode. Loss of utility power is any condition that causes the utility grid
protective relay functions to operate. The Hybrid UPS system will always attempt to power
the critical load once the system has completed its start sequence, unless some condition
causes a complete shutdown (for example, a severe fault on the critical load bus). Table 2
shows four possible scenarios that can occur if utility power is outside of the preset
protective relay limits. Note that scenario 1 is the only condition where reconnection to the
utility will occur as soon as the utility voltage is back within limits. All other scenarios
involve starting a turbine or keeping a turbine running, and therefore the system must wait
for the utility grid reconnect delay. While the battery state of charge will have an impact on
whether the turbine is started or not, reconnection to the Utility grid does not depend on it.
For systems enabled in the UPS Mode, the turbine will continue operating until battery
SOC is above the preset limit before being shut down. If the battery system is provided by
others, the UPS Controller may read state of charge from this external system and provide
the logic and permissive signals to the Hybrid UPS microturbines to start and stop turbines
as shown in Table 2.
Table 2. System Transitions to/from Emergency Mode
Utility
Voltage
OK
Utility
Reconnect
Delay
1
>50%
NO
NO
X
2
>50%
YES
YES
X
X
X
3
<50%
YES or NO
YES
X
X
X
Hi Eff
4
ANY
N/A
RUNNING
X
X
Turbine Keeps
Running
Turbine Stop
No
Wait
Wait for
Battery
SOC
>50%
Utility Reconnection
wait for
Utility
Loss
Scenario
Battery
SOC
Hybrid
UPS
Mode
Turbine
Start
Delay
Timeout
Turbine
Start or
Already
Running
UPS
The normal scenario for transition to and from Emergency Mode is loss of utility voltage
sensed at the incoming connection of all Hybrid UPS system in a group, with the result
that all Hybrid UPS systems enter Emergency Mode. However, it is also possible that an
individual Hybrid UPS system will respond to a utility grid disturbance, or detect an internal
fault condition, and will automatically transition to Emergency Mode while the remaining
Hybrid UPS systems stay in UPS Mode or High Efficiency Mode. This provides for
maximum availability of power to the critical load bus. The individual Hybrid UPS system
will then either automatically transition back to UPS or High Efficiency Mode as shown in
Table 2, or if an internal fault caused the transition, will continue operating in Emergency
Mode until operator intervention corrects the problem.
NOTE
It is possible to have one or more Hybrid UPS system in Emergency
Mode while other systems are in UPS or High Efficiency Mode. Power to
the critical load will be shared equally among all Hybrid UPS systems in
a MultiPac, regardless of the operating mode of each individual system.
