Scotsman MAR 106, Руководство по обслуживанию

Страница: 12 / 42

Page 12
Page 12
4. ELECTRICAL CONNECTIONS
The machine has been wired ready for electric
connections. See nameplate for current
requirements to determine wire size to be used
for electrical hook-up. The MAR flaker requires a
solid earth ground wire. See wiring diagram.
Be certain the unit is connected to its own electrical
circuit and individually fused.
The maximum allowable voltage variation, should
not exceed ten percent of the nameplate rating,
even under starting conditions.
Low voltages can cause erratic operation and
may be responsible for serious damage to the
overload switch and motor windings.
All external wiring should conform to the National,
State and local electrical permit and services of
a licensed electrician will be required.
WARNING - The compressor is equipped
with a crankcase heater which has to be
energized even when the ice maker is
switched-off. So, make sure to connect
the unit with the compressor crankcase
heater constantly energized. After long
inoperative periods remember to give
current to the heater 4 hours before the
ice-maker start-up.
Fuse protection of the unit should be made as
follows:
MAR 56-76-106-126-206 - 3x16 Amps/400V
MAR 306 WS
- 3x24 Amps/400V
MAR 306 ASR - 3x32 Amps/400V
WARNING - Drum drive motor is three-
phases type. At unit start up, correct wiring
is assured by 3 phases monitoring relay
at power in. In addition proper drum
rotation speed is monitored by a Hall
Effect sensor. In case the drum is not
rotating at all or it rotates too slow (less
then 1/4 turn every 30 seconds) a special
Electronic Control trips the unit OFF so to
avoid that compressor can operate with
the drum OFF (in case of fiber keys, drive
motor or gear reducer breakage).
In case of any field drive motor replacement,
care must be taken to its wiring, checking the
correct evaporator drum rotation that MUST
be toward ice blade.
In case of wrong evaporator drum rotation,
turn the unit OFF and exchange two phases
connection at drive motor control box.
5. WATER SUPPLY AND DRAIN CONNECTIONS
Separate water supplies are recommended.
A. Evaporator or ice making supply water should
be run through a hand shut-off valve before
entering unit. Evaporator supply water
connection has a 3/4" male pipe fitting. This
line also has factory installed water strainer
internally mounted. Incoming water goes
through the float reservoir and then to the
drum reservoir. Connect to a good cold water
supply with minimum 1/2 O.D. line. A check
valve on this line will be required in some
cases depending on local plumbing codes.
The recommended minimum water pressure
is 1 bar (14 Psi). Do not operate this unit with
fresh water supply below 1 bar (14 Psi).
Maximum water pressure 5 bar (70 Psi).
B. The condenser water supply line connects to
the following fitting sizes:
MAR 56 - 76
3/4" gas male
MAR 106 - 126 12 mm O.D. fitting
MAR 206
20 mm 0.D. fitting
MAR 306 25 mm
Water supply line size must be adequate to
water flow which, at 15
°
C temperature water, is:
225 lt/hr for MAR 56
300 lt/hr for MAR 76
480 lt/hr for MAR 106
lt/hr for MAR 126
1200 lt/hr for MAR 206
1600 lt/hr for MAR 306
Incoming water goes throughout the water
regulating valve first and then to the water
cooled condenser. Observe arrow on water
regulating valve. Water supply must be installed
to conform with local code. In some case a
licensed plumber and/or a plumbing permit will
be required.
Water Quality
Water quality is a factor of extreme importance
for good operation of MAR machine. Water
shouldn't be too hard neither too soft.
Hard water will tend to create mineral deposits in
water reservoir, evaporator drum and scraping
blade, rendering rough the chute surface which
prevents ice scales from sliding properly into ice
channel. On the contrary, water too soft, (de-
mineralized) will cause the ice skin to stick
excessively on drum surface rendering difficult
the scraping operation of same.
The ideal water should have a total hardness
of about 15-20 french degrees.
Precaution Against Water Frost
Like for any other ice maker all necessary
measures must be taken when the cold season
is approaching to protect the water supply line
and the MAR water system against winter
freezing. If cooling tower is used several
precautions should be observed, too.
1
. Leave water regulating valve in the system.
2. Separate the make-up water for the reservoir
from the tower water.
3. Use 3/4" tower water lines or larger, depending
on the lenght of run. Over 30 feet, use 1" O.D.
lines.
4. NOTICE: a cooling tower can freeze in the
winter time and the MAR flaker will be in
operation 12 months per year. An indoor tower
and pump can be used with outdoors air ducted
in and out if the fan cycles on water tempera-
ture to prevent freezing. An indoor sump can
be used. An auxiliary tower and city-water
hook-up will prove satisfactorily in some
climates. Fresh water in the winter and tower
water during the summer. Consult your tower
and pump manufacturers for proper sizing. In
no event should less than a Nominal 3 to 4 tons
tower, or less than 3/4 HP high pressure tower,
or less than 3/4 HP high pressure tower pump
be used.