Hot-Stick High-Voltage Detectors

Hot-stick high-voltage detectors are models supplied as a detector head together with an insulating stick. On overhead lines, in switchyards and in substations, the absence of voltage is verified by touching the conductor from a safe distance. Maintenance crews of distribution and transmission system operators, industrial companies operating MV/HV installations and contractors are the users of this group.

Three criteria stand out in selection: the nominal voltage of the line, the reach required and the need for AC or DC. Where several models share the same range, the difference lies in the starting (threshold) voltage or the stick length.

Which model?

Model	Operating voltage	Typical use
HST-30	AC 3 kV – 34.5 kV	Distribution lines up to 34.5 kV (e.g. 6 kV – 33 kV)
HST-30L	AC 3 kV – 34.5 kV	L series, starting voltage 500 V ± 100 V
HST-20N	AC / DC 3 kV – 25 kV	Sites with both AC and DC systems
HST-70	AC 20 kV – 80.5 kV	33 kV-class to 66 kV systems
HST-70L	AC 20 kV – 80.5 kV	L series, starting voltage 3000 V ± 600 V
HST-W80L	AC 20 kV – 80.5 kV	L series, starting voltage 5000 V ± 1000 V
HSR-90N	AC / DC 6 kV – 90 kV	Wide range, sealed sensor design
HST-170	AC 60 kV – 195.5 kV	110 kV – 150 kV substations; 3145 mm stick
HST-250	AC 150 kV – 287.5 kV	Transmission above 150 kV (e.g. 220 kV); 5055 mm stick
HSR-500	AC 250 kV – 550 kV	The highest transmission voltages
WM	AC 6.6 kV – 500 kV	Visual detection by a rotating vane

The L-series models use the same battery type and weigh approximately 3 kg. The HST-70L and HST-W80L cover the same range; only their response thresholds differ. On sites with parallel live circuits, a higher threshold generally reduces the risk of misleading indications caused by induced voltage. Where the standard stick does not reach, the G, H and J versions of the HST-30 and the HST-170J can be ordered with longer sticks.

Points to note in use

Hold the stick only by its handle (grip) area; never measure with a damp, dirty or cracked stick. Test the detector before every measurement. A "dead" indication is not a permit to work; work must not start until the line has been earthed with transmission line earthing equipment.

For a summary of all classes see voltage detectors; for model selection see How to Choose a Voltage Detector, and for maintenance see our article on periodic inspection.

Frequently Asked Questions

HST-170 or HST-250 for 150 kV-class systems?

The ranges of the two models overlap between 150 kV and 195.5 kV. For 150 kV-class systems (e.g. 150 kV or 154 kV) the primary choice is the HST-170; if a longer reach is needed, the HST-170J with a 5055 mm stick or the HST-250 can be considered.