Page 49 - Energize August 2022

TECHNICAL

• Fault detection, in its most basic form, is achieved by a current
transformer which feeds the switch directly or via the control device.
Current transformers are fitted on the outgoing side of the switch.
• The switch operating mechanism is used to close the switch and may
also be used to open the switch from a remote signal.
• The controller is used to control the operation of the reclose and
lockout cycle.
• Communications, monitoring and recording devices are fitted to
the more modern types. These allow communication with a central
control site as well as other reclosers; they record voltage and
current levels and other relevant data.
• Sensing and monitoring devices monitor voltage, current and other
parameters.

The intelligent recloser offers a number of additional monitoring and
protection features which make managing the network easier. Most
reclosers offer the following features:
• Trip functions
- Phase over current
- Earth fault
- Sensitive earth fault (SEF)
• Trip or alarm only
- Under/over voltage
- Under/over frequency
- Rate of change of frequency
- Neutral voltage displacement
- Broken conductor
- Loss of phase

The following functions can be provided in addition to basic functions
• Inrush restraint (zero detect/2nd harmonic)
• Directional protection
• Directional blocking
Figure 1: Typical recloser and control unit (Schneider) • Fault location

Figure 2: Stand-alone and networked recloser Figure 3: Typical recloser structure (ABB)

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