Trane CVGF Product Manual page 17

Momentary Power Loss and
Distribution Fault Protection
Three-phase momentary power loss
(MPL) detection gives the chiller
improved performance through many
different power anomalies. MPLs of 2.5
cycles or longer will be detected and
cause the unit to shut down. The unit
will be disconnected from the line
within 6 line cycles of detection. If
enabled, MPL protection will be active
any time the compressor is running.
MPL is not active on reduced-voltage
starters from the initial start signal
through transition. The MPL diagnostic
is an automatic reset diagnostic. MPL
protection can be disabled in TechView.
An MPL has occurred when the motor
no longer consumes power. An MPL
may be caused by any drop or sag in
the voltage that results in a change in
the direction of power flow. Different
operating conditions, motor loads,
motor size, inlet guide vane (IGV)
position, etc. may result in different
levels at which this may occur. It is
difficult to define an exact voltage sag
or voltage level at which a particular
motor will no longer consume power,
but we are able to make some general
statements concerning MPL protection:
The chiller will remain running under
the following conditions:
• Line-voltage sag of 1.5 line cycles or
less for any voltage magnitude sag
• Control-voltage sags of less than 3
line cycles for any magnitude sag
• Control-voltage sags of 40 percent or
less for any amount of time
• Second-order or lower harmonic
content on the line
CTV-PRC001-GB
Controls
The chiller may shut down under the
following conditions:
• Line-voltage sags of 1.5 or more line
cycles for voltage dips of 30 percent
or more
• Control-voltage sags of 3 or more line
cycles for voltage dips of 40 percent
or more
• Third-order or higher harmonic
content on the line
Current Overload Protection
The control panel will monitor the
current drawn by each line of the motor
and shut the chiller off when the
highest of the three line currents
exceeds the trip curve. A manual reset
diagnostic describing the failure will be
displayed. The current overload
protection does not prohibit the chiller
from reaching its full-load amperage.
The chiller protects itself from damage
due to current overload during starting
and running modes, but is allowed to
reach full-load amps.
High Motor-Winding Temperature
Protection
This function monitors the motor
temperature and terminates chiller
operation when the temperature is
excessive. The controller monitors each
of the three winding-temperature
sensors any time the controller is
powered up, and displays each of the
temperatures at the service menu.
Immediately prior to start, and while
running, the controller will generate a
latching diagnostic if the winding
temperature exceeds 265 ± 5°F
(129.4 ± 2.8°C).
Standard
Protections
Surge Detection Protection
Surge detection is based on current
fluctuations in one of three phases. The
default detection criterion is two
occurrences of RMS current change of
30 percent within 0.8 seconds in 60 + 10
percent seconds. With the Tracer
chiller controller, the detection criterion
is adjustable.
Overvoltage and Undervoltage
Protection
The unit will be shut down with an
automatic reset if the line voltage is
below or above 10 percent of nominal.
Must trip = 15 percent of nominal.
Time to trip = minimum of 1 minute, 10
seconds and maximum of 5 minutes,
20 seconds. Overvoltage and
undervoltage protection can be
disabled using TechView.
Power Factor and kW Measurement
Three-phase measurement of kW and
unadjusted power factor yields higher
accuracy during power imbalance
conditions than with CH530.
Short-Cycling Protection
Short-cycling protection is based on a
start-to-start time. This method uses a
straight start-to-start timer to determine
when to allow the next start.
A 'Restart Inhibit Start-to-Start Time'
setpoint is used to set the desired start-
to-start time. There is no 'free' start on
a power up at DynaView. The real-time
clock is used to determine when the
next start will be allowed, based on the
previous start.
When the start is inhibited by the
restart-inhibit function, the time
remaining is displayed along with the
restart-inhibit mode.
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