
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 significant power fluctuations can be supplied
with a control power regulator. See Figure 19, Recommended
Regulator Installation.
Figure 19 - Recommended Regulator Installation