40
Wye-Delta Starting (Open Transition)
There are two critical timing parameters associated with
starting the Paragon compressor with an open transition
wye-delta starter. The first is the maximum duration of
running in the wye connection. It is recommended that
the duration of the wye connection be 5 seconds. The
duration of the wye connection can be longer but in no
case should exceed 10 seconds.
This is necessary to
limit the potential for excessive heating of the motor.
The second critical timing parameter is the duration of the
power interruption from when the wye connection is bro-
ken to when the delta connection is made. It is recom-
mended that the duration of this interruption not exceed
the values given in Table 21 for single compressor cir-
cuits. A shorter duration may be required i
f compressor
must start against head pressure. Starter selections
should be made such that this limit is not exceeded. Lon-
ger interruption times could lead to excessive decelera-
tion during the power interruption. Low running speed at
transition will result in inrush currents similar to the delta
locked rotor current.
Table 21 — Maximum Transition Time
Table 22 shows the wiring configuration for an open tra
n-
sition wye-delta start configuration.
Table 22 — Wye-Delta Start Configuration Wiring
Motor Windings Thermistor
The motor winding thermistor is embedded directly into
the windings of the motor. The thermistor is an NTC type
with a standard resistance of 5000 ohms at 77°F (25°C).
All Paragon compressor motors are supplied with a spare
thermistor to be used if the primary thermistor fails. Table
23 lists the resistance versus temperature characteris-
tics. Additio
nal information regarding this sensor can be
obtained from Carlyle Application Engineering.
Table 23 — Resistance vs Temperature
MODEL MAXIMUM TRANSITION TIME
TS 0.035 seconds
TT 0.055 seconds
TU 0.060 seconds
TV 0.060 seconds
CONNECTION L1 L2 L3
TIE
TOGETHER
Start (wye)
(5 seconds)
1
(U1)
2
(V1)
3
(W1)
4, 5, 6
(U1, V2, W2)
Run (delta)
1, 6
(U1, W2)
2, 4
(V1, U2)
3, 5
(W1, V2)
—
TEMPERATURE RESISTANCE
C
±C
F ohms
–30 .35 –22 88480.0
–25 .33 –13 65205.0
–20 .30 –4 48536.0
–15 .28 5 36476.0
–10 .20 14 27663.0
–5 .20 23 16325.0
5 .20 41 12696.0
10 .20 50 9949.5
15 .20 59 7855.5
20 .20 68 6246.0
25 .20 77 5000.0
30 .20 86 4028.4
35 .20 95 3265.7
40 .20 104 2663.2
45 .20 113 2184.2
50 .20 122 1801.2
55 .20 131 1493.1
60 .20 140 1243.9
65 .20 149 1041.4
70 .20 158 875.8
75 .23 167 739.7
80 .26 176 627.6
85 .29 185 534.9
90 .32 194 457.7
95 .35 203 393.3
100 .38 212 339.3
105 .41 221 293.8
110 .44 230 255.3
11
5 .47 239 222.6
120 .50 248 194.8
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