IONPURE
®
DC POWER CONTROLLER
– IP-POWER600-G2
IP-POWER600-G2 MAN REV. 11
Page 20 of 28
Other Transformer Design Considerations:
Temperature Rise and Insulation Class:
Transformers with 130 or 150 °C temperature rise with an insulation class of 220 °C are commonly
available. Transformers with lower temperature rise are more efficient and have longer service life,
but are priced higher.
Selection is left up to the user. IEC standards specify the maximum temperature rise of
transformers in relation to the insulating material used, for a maximum ambient temperature of
40°C, as listed in Table 4.
Table 4: Transformer Ratings by Insulation Class
Insulation Class
(°C)
Max Permitted Temperature Increase in
Windings (ºC)
(IEC60085)
(IEC60026)
(EN61558)
105 (A)
60
60
120 (E)
75
75
130 (B)
80
80
155 (F)
100
100
180 (H)
125
125
220
150
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Construction:
Use open frame transformers with copper windings. Copper-wound transformers are usually more
efficient and smaller than aluminum-wound units.
Thermal Switch:
It is recommended to have a thermal switch embedded in the secondary winding to shut off the AC
supply to the transformer if the temperature exceeds a set value, below the insulation class
temperature.
Voltage Taps:
Voltage taps in the primary are recommended by most transformer manufacturers. A common tap
arrangement is two 2.5% taps above and four 2.5% taps below nominal voltage. Transformers are
shipped with the taps connected for nominal voltage. The installing electrician must change the taps
if the supply voltage differs from the nominal voltage rating.
A.2
Other Power Supply Assembly Components
Fuses and Circuit Breakers:
“Very fast acting” type fuses or a circuit breaker with a fast tripping curve must be installed
between the output of the isolation transformer and the AC input of the power controller.
