This section of LEC 61558 covers the safety aspects of transformers, reactors, power units, and their combinations, such as electrical, thermal, and mechanical safety This document covers the following independent or related fixed or portable dry-type transformers, power supply units, including switching power supply units, reactors, and their combinations in the field of safety. The windings can be packaged or not, and they do not form a part of the distribution network
Note 1: The difference between transformers, power supply units, and switch mode power supply units is as follows:
- For transformers, the frequency does not change, but the internal resonance frequency of transformers (such as constant voltage)
transformers) does not exceed 30 kHz For power supply units, the internal working frequency and waveform are different from the power frequency and waveform, and the internal working frequency does not exceed 500 Hz (see definition 3.1.19) For switching power supplies, the internal operating frequency and waveform are different from the power supply frequency and waveform. The internal operating frequency exceeds 500 Hz and does not exceed 100 MHz The relevant parts of LEC 61558-2 can be found in the introduction section of this document
(A) Fixed or portable, single-phase or multiphase, air-cooled (natural or forced),
Isolation and safety isolation transformers that are independent or related to the following characteristics:
- Rated supply voltage not exceeding 1000 VAC- The rated power supply frequency shall not exceed 500 Hz
and comply with the following values, unless otherwise specified in the relevant parts of IEC 61558-2:
For isolation transformers:
- Rated output of single-phase transformers, not exceeding 25 kVA, and poly phase transformers not exceeding 40 kVA;
The no-load output voltage and rated output voltage exceeding 50 V AC, not exceeding 500 V AC, or 1000 V AC must comply with national regulations or special purposes
Safety isolation transformer:
- The rated output power of single-phase transformers shall not exceed 10 kVA, and that of polyphase transformers shall not exceed 16 kVA
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