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RTHD-SVX01L-EN
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.
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 provide a smooth load ramp 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 it will be
controllable through TD7/Tracer® TU, External Hardware
Interface or Tracer (if Tracer is installed). Order for
precedence for all setpoints, TD7/Tracer TU, then External
then Tracer from lowest to highest priority. If one of the
higher priority setpoints drops out due to a bad sensor or
communication loss then base loading shall go to the next
lowest priority of command and setpoint. The command
settings and control setpoints associated with base loading
are explained below.
Base Loading Control Setpoint
This setpoint has three possible sources, an External
Analog Input, TD7/Tracer® TU or Tracer®.
• TD7/Tracer TU Base Loading Control Setpoint.
• The range is 40 - 100% Compressor Load (Max %
RLA). The default is 50%.
• Tracer Base Loading Control Setpoint.
• The range is 40 - 100% Compressor Load (Max %
RLA). The default is 50%.
• External Base Loading Setpoint.
This is an Analog Input that sets the base loading setpoint.
This signal can be controlled by either a 2-10Vdc or 4-
20ma Signal based on configuration information. The
equations show the relationship between input and percent
compressor load:
If the input is configured as a 4 - 20 mA:
% Load = 3.75 * (mA Input) + 25
If the input is configured as a 2 - 10 Vdc:
% Load = 7.5 * (Vdc Input) + 25
Ice Building Contact - Optional
Symbio™ 800 accepts a contact closure input to initiate Ice
Building. When in the ice building mode, the compressor
will be fully loaded (not given a low setpoint) and will
continue to operate until the ice contacts open or the return
water temperature reaches the Ice Termination Setpoint. If
terminated on return setpoint, Symbio 800 will not allow
chiller to restart until ice building contact is opened.
Ice Building Control - Optional
Symbio 800 provides an output contact closure that can be
used as a signal to the system that ice building is in
operation. This relay will be closed when ice building is in
progress and open when ice building has been terminated
by either Symbio 800 or remote interlock. It is used to
signal the system changes required to convert to and from
ice building.
Installation Electrical
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