York MILLENNIUM YCAS Installation Operation & Maintenance page 19

current overload conditions. The module responds to
changes in current and must be calibrated using DIP
switches located on the module. Integral trip curves al-
low for in-rush currents during Wye-Delta, part-wind or
ACL starts without nuisance tripping.
To check the factory setting of the 2ACE module cur-
rent overload trip value, obtain the RLA from the motor
nameplate. The method used to calculate the trip value
will depend on the type of start (Across-The-Line or
Wye-Delta) and the number of wires in each phase that
are routed through the C.T.
For an Across-The-Line start, the trip setting will be
1.35 x RLA, if all wires of each phase are routed through
the C.T. on the 2ACE Module. If half the wires on each
phase (1 of 2, or 2 of 4) are routed through the C.T., the
trip setting should be calculated as 1.35 x RLA/2. If 1
of 4 wires is routed through the C.T., the trip should be
calculated as 1.35 x RLA/4. After calculating the trip
setting using the appropriate formula, refer to Table 1
on pages 20-23 for the dip switch setting. For the loca-
tion of the dip switches and determing the ON position,
refer to the following note.
A switch must be pushed to the left to
place a switch in the ON position.
For a Wye-Delta start, the trip setting will be 1.35 x
0.58 RLA, if all wires of each phase of either the Wye
or Delta wiring are routed through the C.T. on the 2ACE
module. If half the wires on either the Wye or Delta of
each phase (1 of 2, or 2 of 4) are routed through the
C.T., the trip setting should be calculated as 1.35 x 0.58
RLA/2. After calculating the trip setting using the ap-
propriate formula, refer to Table 1 on pages 20-23 for
the dip switch setting. For the location of the dip switches
and determining the ON side of the switches, refer to
Figure 39. As indicated, to place a switch in the ON
position requires pushing the switch to the left.
It is recommended that a YORK Ser-
vice Technician or the YORK factory
be consulted before changing these
settings for any reason, since damage
to the compressor could result.
Changes should never be made unless
it is verified that the settings are in-
correct.
YORK INTERNATIONAL
Any time a dip switch change is made,
power must be cycled OFF and ON to
the module to reprogram the module
to the new value.
Thermal Overload
Three PTC (positive temperature coefficient) ther-
mistors in the motor windings of each phase provides
thermal protection. The sensor resistance stays rela-
tively constant at 1k until a temperature of 130ºC
W
(266ºF) is sensed. The sensor experiences a rapid rise
in resistance beyond this temperature. Whenever the
resistance of one of the sensors reaches 13k
module trips, which ultimately de-energizes the motor's
pilot circuit. Reset is manual after the motor cools and
the sensor resistance drops to 3.25k
Current Imbalance (Loaded & Unloaded) /
Loss of Phase
A 2-second delay at start-up allows for any imbalances
resulting during normal starting conditions. After this
initial delay, the 2ACE module compares the "Operat-
ing Current" to the measured half line current. The "Op-
erating Current" is given by 0.65 x factory overload
current setting.
An unloaded compressor condition occurs when any
measured half line current is less than the "Operating
Current." A current imbalance exceeding an unloaded
level of 25% will result in the motor pilot circuit being
de-energized.
A loaded compressor condition occurs when any mea-
sured half line current is greater than or equal to the
"Operating Current." A current imbalance exceeding a
loaded level of 17% will result in the motor pilot circuit
being de-energized.
Imbalance is defined as:
(High Phase - Low Phase) / High Phase
Improper Phase Sequence
The 2ACE module calculates the phase sequence at
start-up using the three current transformers to deter-
mine whether the three phase sequence on the load
side of the main contactor is miswired. Upon detec-
tion of a miswired motor load, the module will de-en-
ergize the main contactor pilot circuit within 50 milli-
second response time.
FORM 201.18-NM2
2
, the 2ACE
W
.
W
19