6
Electrical Wiring
The.electrical.installation.should.be.in.accordance.with.National.
Electrical.Code,.local.codes.and.regulations ..Proper.overcurrent.
protection.should.be.provided.for.the.fan.motors ..
.
All.standard.motors.have.internal.inherent.overload.protectors ..
Therefore,.contactors.can.be.used.instead.of.starters.requiring.
thermal.protectors,.eliminating.the.problem.of.furnishing.the.
proper.heating.elements ..
.
All.air-cooled.condensers.are.furnished.with.either.single-phase.
or.three-phase.fan.motors.which.are.identified.by.the.unit.
dataplate ..
.
Electrical.leads.from.each.motor.terminate.at.the.unit.junction.
box ..Field.connections.must.be.made.from.these.leads.in.
accordance.with.local,.state.and.national.codes ..
.
Three-phase.motors.must.be.connected.to.three-phase.power.of.
voltage.to.agree.with.motor.and.unit.dataplate ..
.
The.motors.are.wired.into.a.common.junction.box ..Where.
fan.cycling.is.furnished.and.factory.installed,.the.motors.are.
completely.wired.through.the.control.and.to.the.contactors ...The.
motors.must.be.checked.for.proper.rotation ..Be.sure.to.check.that.
motor.voltage.and.control.connection.agree.with.electric.services.
furnished .
Discharge Lines
The.proper.design.of.discharge.lines.involves.two.objectives:.
1 .. To.minimize.refrigerant.pressure.drop,.since.high.. .
pressure.losses.cause.increased.compressor..
.
.
horsepower.per.ton.of.refrigerant .
2 .. To.maintain.sufficiently.high.gas.velocity.to.carry.oil..
.
through.to.the.condenser.coil.and.receiver.at.all.loading..
.
conditions .
Table 2. Condensing Temperature Correction Factor
Condensing
Temperature
Discharge Line
R-22
R-502
R-404A
R-507
R-407C
R-410A
R-134A
90
0 .88
0 .91
0 .922
0 .924
0 .872
0 .889
0 .882
100
0 .95
0 .97
0 .974
0 .975
0 .957
0 .963
0 .961
110
1 .04
1 .02
1 .009
1 .005
1 .036
1 .032
1 .026
120
1 .10
1 .08
1 .026
1 .014
1 .009
1 .096
1 .078
130
1 .18
1 .16
1 .043
1 .024
1 .182
1 .160
1 .156
Table 1. Tons of Refrigeration
Line Size
Type L Copper
OD
Discharge Line
Drain Line
Velocity 100 FPM Refrigerant
R-22 Sat. Suction Temp (°F)
R-404A/R-507 Sat. Suction Temp (°F)
-40
0
40
-40
0
40
R-22
R-404A
1/2
0 .75
0 .8
0 .85
0 .56
0 .63
0 .7
2 .3
1 .5
5/8
1 .4
1 .5
1 .6
1 .0
1 .2
1 .3
3 .7
2 .3
7/8
3 .7
4 .0
4 .2
2 .7
3 .1
3 .4
7 .8
4 .9
1-1/8.
7 .5
8 .0
8 .5
5 .5
6 .3
7 .0
13 .2
8 .3
1-3/8
13 .1
14 .0
14 .8
9 .6
10 .9
12 .1
20 .2
12 .6
1-5/8
20 .7
22 .0
23 .4
15 .2
17 .2
19 .1
28 .5
17 .9
2-1/8
42 .8
45 .7
48 .5
31 .4
35 .6
39 .5
49 .6
31 .1
2-5/8
75 .4
80 .4
85 .4
55 .3
62 .8
69 .5
76 .5
48 .0
3-1/8
120 .2
128 .2
136 .2
87 .9
99 .8
110 .5
109 .2
68 .4
3-5/8
178 .4
190 .3
202 .1
130 .5
148 .1
164 .0
147 .8
92 .6
4-1/8
251 .1
267 .8
284 .4
183 .7
208 .4
230 .9
192 .1
120 .3
Source:..ASHRAE.Refrigeration.Handbook:
1 .. Line.sizes.based.on.pressure.drop.equivalent.to.1°F.per.100.equivalent.feet .
2 .. Values.in.Table.are.based.on.105°F.condensing.temperature ...Multiply.Table.capacities.by.the.factors.in.Table.2.for.other.condensing.temperatures .
3 .. If.subcooling.is.substantial.or.the.line.is.short,.a.smaller.line.size.may.be.used ..Applications.with.very.little.subcooling.or.very.long.lines.may.require.larger.sizes
WARNING:
..There.may.be.more.than.one.source.of.electrical.current.in.this.unit ...Do.not.service.before.disconnecting.all.power.supplies .
