Appendix A - HPS NH Serie Guía De Instalación, Operación Y Mantenimiento

poles.
Conventional open ventilated dry-type
transformers have a bottom screen for air convection.
When transformers are mounted above the ground
surface a catcher plate should be installed under each
transformer as a safety precaution against any hot
particles that may fall through the screen in the event
of a faulted condition. Refer to Appendix B (page 8).
2) Sound Isolation Pads
All dry-type transformers have rubberized sound
absorbing pads mounted internally between the core
and coil assembly and the enclosure.
For maximum absorption of vibration and
emission of sound, additional sound isolation pads are
recommended for installation between the transformer
and the mounting surface.
These molded neoprene and steel plate
assemblies virtually eliminate vibration noise between
the transformer and the mounting surface.
Consult the manufacture's catalog for the part
number of the correct isolation pad required
3) Connectors
Connectors for the installation of dry-type
transformers are readily available. These connectors
are suitable for either copper or aluminum cable.
Connectors should be sized and installed in
accordance with your local electrical code
requirements using the best practices to ensure safe
and reliable operation. Cable surfaces should be
cleaned and electrical compound should be used for
all joints.
Selecting Connectors
a) Determine the primary current for the required
transformer from the Appendix A.
b) Similarly, determine the secondary current rating
for the transformer from Appendix A.
c) For 120/240 voltage connections the current
should be based on 240 volts.
d) For 240/480 volt connections, the current should
be based on 480 volts.
AMPACITY RATINGS FOR CONNECTIONS
A. For a single phase transformer
Line Amperes = volt-amperes
B. For a three phase transformer
Line Amperes = volt amperes
Full Load Current Table
Single Phase Transformer
kVA
Rating 120V 240V 416V 480V 600V
3 25.0
5 41.6
7.5 62.5
10 83.3
15 125
25 208
37.5 312
50 416
75 625
100 833
150 1250
167 1391
250 2083
333 2775
Full Load Current Table
Three Phase Transformer
kVA
Rating 208V 240V 380V 416V 480V
2 5.55
3 8.32
6 16.6
9 24.9
15 41.6
30 83.2
45 124
75 208
112.5 312
150 416
225 624
300 832
450 1249
500 1387
600 1665
750 2081
- 7 -

APPENDIX A

line volts
3 X line Volts
Current in Amperes
12.5 7.21 6.25
20.8 12.0 10.4
31.2 18.0 15.6
41.6 24.0 20.8
62.5 36.0 31.2
104 60.0 52.0
156 90.1 78.1
208 120 104
312 180 156
416 240 208
625 360 312
695 401 347
1041 600 520
1387 800 693
Current in Amperes
4.81 3.03 2.77 2.40
7.21 4.55 4.16 3.60
14.4 9.11 8.32 7.21
21.6 13.6 12.4 10.8
36.0 22.7 20.8 18.0
72.1 45.5 41.6 36.0
108 68.3 62.4 54.1
180 113 104 90.2
270 170 156 135
360 227 208 180
541 341 312 270
721 455 416 360
1082 683 624 541
1202 759 693 601
1443 911 832 721
1804 1139 1040 902
5.00
8.33
12.5
16.6
25.0
41.6
62.5
83.3
125
166
250
278
416
555
600V
1.92
2.88
5.77
8.66
14.4
28.8
43.3
72.1
108
144
216
288
433
481
577
721