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FORM 160.55-O1 (604)
105
YORK INTERNATIONAL
in series to achieve a 900VDC capability for the DC
link. It is important the voltage is shared equally from
the junction of the center or series capacitor con nec tion,
to the negative bus and to the positive bus. This center
point should be approximately ½ of the total DC link
voltage.
“HARMONIC FILTER – INPUT
CURRENT OVERLOAD”
The three phases of RMS Þ lter current are monitored
and if any one of the three phases continuously ex ceeds
a given threshold for 7 seconds, a chiller shutdown is
performed and this message is displayed. The max i mum
permissible continuous RMS current ratings for the har-
monic Þ lter are:
351/292 HP = 128 AMPS
503/419 HP = 176 AMPS
790/658 HP = 277 AMPS
“HARMONIC FILTER – LOGIC BOARD
POWER SUPPLY”
The low voltage power supplies on the Þ lter logic board
have decreased below their permissible operating range.
The Þ lter logic board receives its power from the VSD
logic board via the ribbon cable, connecting the two
boards.
“HARMONIC FILTER – RUN SIGNAL”
When a digital run command is received at the Þ lter logic
board from the VSD logic board via the 16 po si tion rib-
bon cable, a 1/10 second timer is started. If a redundant
run command does not occur on the serial data link from
the VSD logic board before the timer expires, a shut-
down is performed and this message is generated.
“HARMONIC FILTER – DC CURRENT
TRANSFORMER 1”
During initialization, with no current ß owing through the
DC Current Transformers (DCCT’s), the DCCT out put
voltages are measured and compared with a preset limit
via the Þ lter logic board. If the measured values exceed
the preset limits, the DCCT’s are presumed to be defec-
tive and this shutdown is generated.
“HARMONIC FILTER – DC CURRENT
TRANSFORMER 2”
See “Harmonic Filter – DC Current Transformer 1”
message above.
SAFETY SHUTDOWN MESSAGES
“EVAPORATOR – LOW PRESSURE”
(This message is applicable only if the Smart Freeze
feature is not activated. If Smart Freeze is activated and
has initiated the shutdown, “Evaporator – Low Pres sure
– Smart Freeze” is displayed as described next.)
The evaporator pressure, as sensed by the Evaporator
Transducer, has decreased to the Safety shutdown thresh-
old. For water cooling applications, the safety shut down
threshold is a Þ xed value for the respective re frig er ant. For
Brine cooling applications, the safety shut down thresh old
varies according to the con cen tra tion of the Brine solu-
tion. The Brine shutdown thresh old is pro grammed at the
YORK Factory. It should not be changed by any one other
than a qualiÞ ed Service Technician fol low ing instructions
in YORK Service Manual 160.55-M1. The chiller can be
started after the evaporator pres sure in creas es to the restart
threshold and the COM PRES SOR switch is placed in the
Stop-Reset (O) po si tion.
Shutdown (PSIA) Restart (PSIA)
Water cooling - R11 <5.4 >5.4
R123 <4.4 >
4.4
Brine cooling - R11/R123 0.0 to 12.5 >
as programmed Shutdown threshold
“EVAPORATOR – LOW PRESSURE – SMART
FREEZE”
Smart Freeze Protection is activated and has shut down
the chiller because the evaporator tem per a ture has been
below the Smart Freeze thresh old for greater than the al-
lowable num ber of seconds. If the evaporator re frig er ant
tem per a ture sensor RT7 is Enabled (using pro ce dure in
Service Man u al 160.55-M1), this pa ram e ter is used as
the evaporator refrigerant tem per a ture and the freeze
threshold is 32.8°F. If RT7 is not Enabled, the evaporator
refrigerant temperature used is the Evap o ra tor Satura-
tion Temperature, derived from the Evap o ra tor Pres sure
Trans duc er and the freeze threshold is 34.0°F.
The count is incremented once for every second the
evaporator refrigerant temperature is below the freeze
threshold (but is never decremented below zero). The
number of seconds it will take the chilled liquid to
freeze is based on how far the evaporator refrigerant
tem per a ture is below the freeze threshold as follows:
Number of seconds to freezing = (4053.7) / (freeze
thresh old-evaporator refrigerant temperature)
Smart Freeze is activated only if the feature has been
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