RTHD-SVX01L-EN
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The Reset Ratio on the User Interface is displayed as a
percentage. To use it in the above equation it must be
converted to its decimal form.
Reset Ratio percent / 100 = Reset Ratio decimal
Example of converting Reset Ratio:
If the Reset Ratio displayed on the User Interface is 50%
then use (50/100) = 0.5 in the equation.
Abbreviations used in equations:
• TOD = Outdoor Air Temp
• TWE = Evap Entering Water Temp
• TWL = Evap Leaving Water Temp
Programmable Relays (Alarm and Status) -
Optional
Symbio 800 provides a flexible alarm or chiller status
indication to a remote location through a hard wired
interface to a dry contact closure. Four relays are available
for this function, and they are provided (generally with a
Quad Relay Output LLID) as part of the Alarm Relay
Output Option.
The events/states that can be assigned to the
programmable relays are listed in the following table.
Table 11. Chiller events/status descriptions
Event/State
Description
Alarm - Latching
This output is true whenever there is any
active diagnostic that requires a manual reset
to clear, that affects the Chiller, the Circuit, or
any of the Compressors on a circuit. This
classification does not include informational
diagnostics.
Alarm - Auto Reset
This output is true whenever there is any
active diagnostic that could automatically
clear, that affects the Chiller, the Circuit, or
any of the Compressors on a circuit. This
classification does not include informational
diagnostics. If all of the auto resetting
diagnostics were to clear, this output would
return to a false condition.
Alarm
This output is true whenever there is any
diagnostic effecting any component, whether
latching or automatically clearing. This
classification does not include informational
diagnostics.
Warning
This output is true whenever there is any
informational diagnostic affecting any
component, whether latching or automatically
clearing.
Table 11. Chiller events/status descriptions
(continued)
Event/State
Description
Chiller Limit Mode
This output is true whenever the chiller has
been running in one of the Unloading types of
limit modes (Condenser, Evaporator, Current
Limit or Phase Imbalance Limit) continuously
for the last 20 minutes. A given limit or
overlapping of different limits must be in
effect continuously for 20 minutes prior to the
output becoming true. It will become false, if
no Unload limits are present for 1 minute.
The filter prevents short duration or transient
repetitive limits from indicating. The chiller is
considered to be in a limit mode for the
purposes of front panel display and
annunciation, only if it is fully inhibiting
loading by virtue of being in either the “hold”
or “forced unload” regions of the limit control,
excluding the “limited loading region”.
Compressor Running
The output is true whenever any
compressors are started or running on the
chiller and false when no compressors are
either starting or running on the chiller.
This status may or may not reflect the true
status of the compressor in Service
Pumpdown if such a mode exists for a
particular chiller.
Chiller Head Pressure
Relief Request Relay
This relay output is energized anytime the
chiller is running in one of the following
modes; Ice Building Mode or Condenser
Pressure Limit Control Mode continuously for
the duration specified by the Chiller Head
Relief Relay Filter Time. The Chiller Head
Relief Relay Filter Time is a service setpoint.
The relay output is de-energized anytime the
chiller exits all above modes continuously for
the duration specified by the same Chiller
Head Relief Relay Filter Time.
The Symbio 800 Service Tool (Tracer® TU) is used to
install and assign any of the above listed events or status
to each of the four relays provided with this option.
The default assignments for the four available relays are
listed below.
Table 12. Programmable relays
LLID Name
LLID
Software
Relay
Designation
Output Name
Default
Operating Status
Programmable
Relays
Relay 0
Status Relay 4,
J2-1,2,3
Head
Pressure
Relief Request
Relay 1
Status Relay 3,
J2-4,5,6
Chiller Limit
Mode Relay
Relay 2
Status Relay 2,
J2-7,8,9
Chiller Alarm
Relay (latching
or nonlatching)
Relay 3
Status Relay 1,
J2-10,11,12
Compressor
Running Relay
Installation Electrical
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