RWH ROTARY SCREW COMPRESSOR UNITS
INSTALLATION
070.620-IOM (DEC 12)
Page 15
CURRENT TRANSFORMER (CT) RATIOS
The CT ratio for various motor sizes (with a 5 amp second ary) is given in the following table:
CT Factor
Voltage
HP 380 460 575 2300 3300 4000 4160 6000 6300 10,000 13,200
400 800:5 600:5 500:5 200:5 100:5 100:5 100:5 50:5 50:5 50:5 50:5
450 1000:5 800:5 600:5 200:5 200:5 100:5 100:5 100:5 100:5 50:5 50:5
500 1000:5 800:5 600:5 200:5 200:5 100:5 100:5 100:5 100:5 50:5 50:5
600 1200:5 1000:5 800:5 200:5 200:5 200:5 100:5 100:5 100:5 50:5 50:5
700 1200:5 1000:5 200:5 200:5 200:5 200:5 100:5 100:5 50:5 50:5
800 1000:5 300:5 200:5 200:5 200:5 100:5 100:5 100:5 50:5
900 1200:5 300:5 300:5 200:5 200:5 200:5 200:5 100:5 50:5
1000 300:5 300:5 200:5 200:5 200:5 200:5 100:5 100:5
1250 400:5 300:5 300:5 200:5 200:5 200:5 100:5 100:5
1500 500:5 400:5 300:5 300:5 200:5 200:5 100:5 100:5
2000 600:5 500:5 400:5 400:5 300:5 300:5 200:5 200:5
2500 700:5 600:5 500:5 400:5 300:5 300:5 200:5 200:5
3000 800:5 700:5 600:5 500:5 400:5 400:5 200:5 200:5
3500 900:5 800:5 700:5 500:5 500:5 400:5 300:5 200:5
4000 1000:5 1000:5 800:5 600:5 500:5 500:5 300:5 300:5
4500 1500:5 1200:5 800:5 800:5 600:5 600:5 300:5 300:5
5000 2000:5 1200:5 900:5 900:5 600:5 600:5 400:5 300:5
5500 2000:5 1500:5 1000:5 1000:5 700:5 700:5 400:5 300:5
6000 2000:5 1500:5 1200:5 1200:5 800:5 700:5 400:5 400:5
6500 2000:5 2000:5 1200:5 1200:5 800:5 800:5 500:5 400:5
MINI MUM BURDEN RATINGS
The following table gives the minimum CT burden ratings.
This is a function of the distance between the motor starting
package and the compressor unit.
BURDEN
RATING
MAXIMUM DISTANCE FROM
FRICK PANEL
ANSI VA
USING # USING # USING #
14 AWG 12 AWG 10 AWG
B-0.1 2.5 15 ft 25 ft 40 ft
B-0.2 5 35 ft 55 ft 88 ft
B-0.5 12.5 93 ft 148 ft 236 ft
CONTROL POWER REGULATOR
Compressor units that will be used in areas that suffer brown
outs and other signicant power uctuations can be supplied
with a control power regulator. See Figure 19, Recommended
Regulator Installation.
Figure 19 - Recommended Regulator Installation