# Types of duty

**Types of operation.
**There are the following types of operation:

**1. Continuous operation - (S1) **Operation with a constant load and for an unlimited period of time or at least until a determined temperature increase is achieved. Figure 1 below shows operating period and temperature rise verses time for continuous operation.

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Fig.1 Continuous operation (S1)

Tmax – temperature determined for continuous operation.

Descriptions: Moc – Power, Straty elektryczne – Electric losses, Temperatura - Temperature

**2. Short-time operation - (S2)** Operation for a determined period of time, starting from cold state, with breaks in operation long enough to cool the transformer down to a temperature close to ambient. Operating time (tp ) is given in minutes (e.g. S2-15 min.). Figure 2 below shows operating duty cycle and temperature rise for short-time operation.

Fig. 2 Short-time operation (S2)

Tmax – highest temperature at short-time operation, tp – time of short-time operation.

Descriptions: Moc – Power, Straty elektryczne – Electric losses, Temperatura - Temperature

**3. Discontinuous operation - (S3)** Consecutive periods of operation and break with a predetermined duty cycle. Discontinuous operation may be designated for example as S3-20%, where the percentage value indicates the ratio of operation time (tp) to the cycle period (t0), where t0 =tp+ts.

Figure 3 below shows operating duty cycle and temperature rise for discontinuous operation.

Fig. 3 Discontinuous operation (S3)

Tmax – highest temperature at discontinuous operation, tp – time of operation, t0 –period duration,

ts – standstill duration.

Description: Moc – Power, Straty elektryczne – Electric losses, Temperatura - Temperature