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CVHE-SVU01E-EN
68
Momentary Power Loss (MPL)
Protection.
Improved power measurement and
protection algorithms allow the unit
to accommodate more power
anomalies than ever. If the chiller
must shut down, faster restarts get
the machine up and running as soon
as possible.
Momentary power loss (MPL) detects
the existence of a power loss to the
compressor motor and responds by
initiating the disconnection of the
compressor motor from the power
source. Power interruptions of less
than 30 line-cycles are defined as
momentary power losses. Tests have
shown that these short-term power
interruptions can be damaging to the
motor and compressor if the chiller
is reconnected to the line while the
motor and line phases do not match.
The chiller will be shut down when a
MPL is detected and will display a
non-latching diagnostic indicating
the failure. The oil pump will be run
for the post-lube time period when
power returns. The compressor and
compressor motor are protected from
damage from large torques and
inrush currents resulting from
reconnecting the compressor motor
to the power source following a
momentary loss of power.
MPL’s greater than 2 or 3 cycles are
detected resulting in unit shut down.
Disconnection from the line is
initiated within 6 line cycles of the
power loss. MPL protection is active
anytime the compressor is in the
running mode. (The transition
complete input has been satisfied).
MPL is enabled however can be
disabled, if required via the service
tool.
Figure 25. CVHE, CVHF, and CVHG sequence of operation: momentary power loss, (DynaView
™
and Starter module
remain powered)
Machine Protection
and Adaptive
Control