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Installation Electrical
Table 14. Chiller events/status descriptions (continued)
Event/State
Description
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
Chiller Limit Mode
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".
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
Compressor
chiller.
Running
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.
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
Chiller Head Relief Relay Filter Time. The Chiller
Pressure Relief
Head Relief Relay Filter Time is a service setpoint.
Request Relay
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
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 15
Programmable relays
LLID
Software
Relay
LLID Name
Designation
Relay 0
Relay 1
Operating
Status
Programmable
Relay 2
Relays
Relay 3
Emergency Stop
The Symbio™ 800 provides auxiliary control for a
customer specified/installed latching trip out. When this
customer-furnished remote contact is provided, the chiller
will run normally when the contact is closed. When the
contact opens, the unit will trip off on a manually
resettable diagnostic. This condition requires manual
reset at the chiller switch on the front of the control panel.
46
®
TU) is used to
Output
Name
Default
Status Relay 4,
Head Pressure Relief
J2-1,2,3
Request
Status Relay 3,
Chiller Limit Mode
J2-4,5,6
Relay
Chiller Alarm Relay
Status Relay 2,
(latching or
J2-7,8,9
nonlatching)
Status Relay 1,
Compressor Running
J2-10,11,12
Relay
External Auto/Stop
If the unit requires the external Auto/Stop function, the
installer must provide leads from the remote contacts to
the proper terminals of the LLID on the control panel.
The chiller will run normally when the contacts are closed.
When the contact opens, the compressor(s), if operating,
will go to the RUN:UNLOAD operating mode and cycle off.
Unit operation will be inhibited. Re-closure of the contacts
will permit the unit to automatically return to normal
operation.
Note: An immediate stop (similar to "emergency" stop)
can be manually commanded by touching STOP on
the TD7 user interface, then selecting Immediate
Shutdown.
Soft Loading
Soft loading will prevent the chiller from going to full
capacity during the pull-down period.
The Symbio™ 800 control system has two soft loading
algorithms running all of the time. They are capacity
control soft loading and demand limit soft loading. These
algorithms introduce the use of a Filtered Chilled Water
Setpoint and a Filtered Demand Limit Setpoint. After the
compressor has been started, the starting point of the
filtered chilled water setpoint is initialized to the value of
the Evap Leaving Water Temperature. The filtered
demand limit setpoint is initialized to the value of the
Demand Limit Startup Target. These filtered setpoints
allow for a stable pull-down that is user adjustable in
duration. They also eliminate sudden transients due to
setpoint changes during normal chiller operation.
Three settings are used to describe the behavior of soft
loading. The setup for softloading can be done using
®
Tracer
TU.
•
Capacity Control Softload Time: This setting controls
the time constant of the Filtered Chilled Water
Setpoint. It is settable between 0 and 120 min.
•
Demand Limit Softload Time: This Setting controls the
time constant of the Filtered Demand Limit Setpoint. It
is settable between 0 and 120 minutes.
•
Demand Limit Startup Target: This setting controls the
starting point of the Filtered Demand Limit Setpoint. It
is adjustable from 40 for RTHD to 100 percent.
External Base Loading - Optional
Primarily for process control requirements, base loading
provides for immediate start and loading of a chiller up to
an externally or remotely adjustable current limit setpoint
without regard to differential to start or stop, or to leaving
water temperature control. This allows the flexibility to
prestart or preload a chiller in anticipation of a large load
application. It also allows you to keep a chiller on line
between processes when leaving water temperature
control would normally cycle the unit.
When the base loading option is installed through TD7 it
will be controllable through TD7/Tracer
®
TU, External
RTHD-SVX01K-EN
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