York YK Manual page 34
Centrifugal liquid chiller style g
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- Installation instructions manual (48 pages) ,
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FORM 160.75-EG1 (519)
Accessories and Modifications (Cont'd)
every time the contacts close, they bounce. When they bounce, they arc. The arcing that
occurs as the contacts make or break may result in rapid and excessive erosion of the
contacts, causing prematurely short contact life.
Types - YORK
chillers are designed for use with the following types of electromechanical
®
starters, here briefly described.
Across-the-Line (ACL) – These are the simplest and lowest-cost starters available. They
apply full voltage to the three motor leads at the instant of starting. Since inrush is 100%
of LRA and starting torque is 100%, this is the roughest type of starting on the motor and
driveline. In physical size, the ACL is the smallest of electromechanical starters and there
is no transition surge. In most areas, utilities will not permit the use of this type of starter
for chiller-size motors because of their large current draw on startup.
Auto-Transformer (AT) – These starters are reduced-voltage starters. Transformers are
used to step down the voltage to the motor during startup. The result is reduced inrush
current and starting torque at the level of 42% or 64% depending upon whether 65% or
80% voltage taps are used. They provide closed transition (with three-lead motors) with
reduced line disturbance.
Star-Delta Starters – During starting, the motor is connected in a Star or Wye configura-
tion. This reduces the voltage to the motor stator by a factor of three. This 1/3 voltage
results in 1/3 current into the motor at start and 1/3 torque to the shaft. Centrifugal com-
pressor starting torque requirements are low enough to allow the motor to start at 1/3 of
full load torque.
Star-Delta starting creates some stresses for the starter's switch-gear, building electrical
system, power grid, and chiller mechanical driveline. Although these stresses are 1/3 of
the stresses generated by an ACL starter, they cause wear on the system. As a result,
Johnson Controls recommends using a Solid State Starter or Variable Speed Drive in-
stead of a Star-Delta starter.
TABLE 4 - ELECTROMECHANICAL STARTER
STARTER OPTIONS
LV ACROSS THE
LINE (DOL)
380V
(FLOOR MOUNTED)
LV STAR-DELTA
CLOSED
380V
(FLOOR MOUNTED)
STARTER OPTIONS
MV ACROSS THE
LINE (DOL)
2300 3300 4000 4160 6000 6600 12470 13200 2300 3000 3300 6000 6600 10000 11000
(FLOOR MOUNTED)
MV
AUTOTRANSFORMER
2300 3300 4000 4160 6000 6600 12470 13200 2300 3000 3300 6000 6600 10000 11000
65%
(FLOOR MOUNTED)
MV
AUTOTRANSFORMER
2300 3300 4000 4160 6000 6600 12470 13200 2300 3000 3300 6000 6600 10000 11000
80%
(FLOOR MOUNTED)
X = Available
* = Not available with 5DJ motor
O = SQ
34
60HZ
440V
460V
X
X
X
60HZ
440V
460V
X
X
X
60HZ
X
X
X
X
O
60HZ
X
X
X
X
O
60HZ
X
X
X
X
O
LOW VOLTAGE/FREQUENCY
480V
575V
X
X
480V
575V
X
X
MEDIUM VOLTAGE / FREQUENCY
O
O
O
X
O
O
O
X
O
O
O
X
50HZ
380V
400V
X
X
50HZ
380V
400V
X
X
50HZ
X
X
O
O
50HZ
X*
X*
O
O
50HZ
X
X
O
O
JOHNSON CONTROLS
415V
X
415V
X
O
O
O
O
O
O
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