Specifications

56 YORK INTERNATIONAL
MEGGING THE MOTOR
While the main disconnect switch and compressor mo-
tor starter and Variable Speed Drive both open, meg the
motor as follows:
1. Using a megohm meter (megger), meg between
phases and each phase to ground (See Fig. 30); these
readings are to be interpreted using the graph shown
in Fig. 31.
2. If readings fall to the left of the applicable curve, re-
move external leads from the motor and repeat test.
NOTE: Motor is to be megged with the stator at ambi-
ent temperature after 24 hours of idle standby.
FIG. 30 - DIAGRAM, MEGGING MOTOR WINDINGS
CONDENSERS AND COOLERS
GENERAL
Maintenance of condenser and cooler shells is impor-
tant to provide trouble free operation of the chiller. The
water side of the tubes in the shell must be kept clean
and free from scale. Proper maintenance such as tube
cleaning, and testing for leaks, is covered on the follow-
ing pages.
CHEMICAL WATER TREATMENT
Since the mineral content of the water circulated through
coolers and condensers varies with almost every source
of supply, it is possible that the water being used may
corrode the tubes or deposit heat resistant scale in them.
Reliable water treatment companies are available in most
larger cities to supply a water treating process which
will greatly reduce the corrosive and scale forming prop-
erties of almost any type of water.
As a preventive measure against scale and corrosion
and to prolong the life of cooler and condenser tubes, a
chemical analysis of the water should be made prefer-
ably before the system is installed. A reliable water treat-
ment company can be consulted to determine whether
water treatment is necessary, and if so, to furnish the
proper treatment for the particular water condition.
CLEANING COOLER AND CONDENSER TUBES
Cooler
It is difficult to determine by any particular test whether
possible lack of performance of the water cooler is due
to fouled tubes alone or due to a combination of troubles.
Trouble which may be due to fouled tubes is indicated
when, over a period of time, the cooling capacity de-
creases and the split (temperature difference between
water leaving the cooler and the refrigerant tempera-
ture in the cooler) increases. A gradual drop-off in cool-
ing capacity can also be caused by a gradual leak of
refrigerant from the system or by a combination of foul
ed tubes and shortage of refrigerant charge. An exces-
sive quantity of oil in the cooler can also contribute to
erratic performance.
LD00475