Johnson Controls YORK YK Style G OPTIVIEW Operation And Maintenance page 241

FORM 160.54-O1
ISSUE DATE: 9/10/2014
Harmonic Filter – High Total Demand Distortion
This shutdown indicates the filter is not operating cor-
rectly and the input current to the VSD/Filter is not
sinusoidal. This shutdown will occur if the TDD ex-
ceeds 25% continuously for 45 seconds. TDD is an
acronym for Total Demand Distortion, a term defined
by the IEEE Std 519-1992 standard as the total root-
sum-square harmonic current distortion, in percent of
the maximum demand load current (15 or 30 min de-
mand). In the filter option supplied by YORK, the dis-
played TDD is the total RMS value of all the harmonic
current supplied by the main power to the VSD divided
by the chiller Full Load Amps, in percent. A standard
VSD, less the optional filter typically has an input cur-
rent TDD level on the order of 28-30%. The chiller can
be started after the Compressor Switch is placed in the
Stop-Reset (O) position.
JOHNSON CONTROLS
SECTION 3 - DISPLAY MESSAGES
VSD – Low Frequency Detected
(Software version C.MLM.01.14.xxx (and later) or
C.OPT.01.14.306 (and later))
After a 20 second bypass after entering System Run, if
the VSD frequency decreases to below 1Hz less than
the minimum allowed frequency for 25 continuous
seconds, this shutdown is initiated. With software ver-
sion C.OPT.01.19.307 (and earlier), this fault occurs
when the VSD frequency falls below 1Hz less than the
minimum allowed frequency after having reached the
minimum frequency. The minimum allowed frequency
for the VSD is 25Hz for 50Hz units; 30Hz for 60Hz
units. The Compressor Switch is placed in the Stop-
Reset (O) position.
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