Abstract: In an electric fence energizer there is an exterior earth connection such as an earth connection post (16). The electric fence energizer comprises in the conventional way a transformer (T) having a primary winding (L.sub.1) and a secondary winding (L.sub.2), one exterior terminal (9) of which is connected to the conductor (17) in the electric fence and the other exterior terminal (11) is connected to the earth connection, high voltage pulses being induced over the secondary winding (L.sub.2) when voltage pulses are applied over the primary winding (L.sub.1). For a determination of the quality of the earth connection, the voltage over a small part of the secondary winding (L.sub.2) is obtained capacitively by means of an extra winding (L.sub.3) in the transformer (T). For an evaluation of this voltage, it is connected, only for a determined polarity, to a charging circuit for a capacitor (C.sub.2), which is discharged over a known resistor (R.sub.2, R.sub.3). The voltage (V.sub.21) over this capacitor (C.sub.

Abstract: An electric fence energizer is operated by an alternating current and has two storage capacitors (C.sub.1, C.sub.2), which are charged by a charging circuit (7) to a high voltage. The storage capacitors (C.sub.1, C.sub.2) are discharged through separate primary windings (L.sub.1, L.sub.2) in a transformer (T) and the secondary winding (L.sub.3) of the transformer is connected to the electric fence. The discharging processes are controlled by separate discharging circuits (R.sub.1, T.sub.y1 ; T.sub.y3 and T.sub.y3 respectively), so that for light loads only one of the storage capacitors (C.sub.1) is discharged, and for heavy loads also the other one (C.sub.2) is discharged starting a short time after the start of the discharging of the first one and during the same discharge cycle. Sense circuits (L.sub.2, R.sub.8, R.sub.9, C.sub.3, R.sub.10, R.sub.11, R.sub.12, T.sub.4, R.sub.13) provide signals PCHL; PPUL) to a microprocessor (7) and they represent the load on the transformer (T).

Abstract: An electric fence energizing apparatus is described in which a chargeable capacitor is connected to the primary winding of a transformer. The secondary winding of the fence is connected to receive pulses at the discharge of the capacitor, the discharge time serving as a measure of the voltage of the corresponding output pulse on the fence. The primary winding of the transformer is divided into two oppositely connected windings. The capacitor is arranged to be discharged through a first one of the primary windings. A voltage determined by the discharge of the capacitor is produced over the second of the primary windings during the discharge process. A measuring unit measure the time of the duration of this voltage over the second winding determined by the discharge of the capacitor.