Page 187 - Offshore Electrical Engineering Manual

174 CHAPTER 16 Transformers

FIGURE 2.16.1
(A) Transformer phasor diagram. (B) Transformer equivalent circuit.

Dry-type transformers are used offshore, but they must be well protected inside
air-conditioned and pressurised modules, to avoid both the external (salt-laden)
atmosphere and the risk of flammable gases (see Fig. 2.16.2).
Oil-filled transformers are also used, but as mentioned earlier, they do create a
fire hazard, especially if an internal winding fault occurs. Please refer to PART 4
Chapter 2 for further information (see Fig. 2.16.4).
Cast resin transformers are considered the most suitable for offshore use,
although the very large transmission transformers utilised on wind farm substation
are too large for resin casting, and oil dump tanks are used, as mentioned earlier (see
Fig. 2.16.3).