HST-138V Universal Joint High Voltage Detector

HASEGAWA HST-138V is a universal joint high voltage detector that operates in the AC 66 kV – 138 kV range and attaches to a common insulating stick via a universal joint. It signals a live conductor with an intermittent sound of at least 70 dB and a red LED that can be seen at 8000 lx ambient light. It was developed for substation operating staff, maintenance contractors working in transmission installations and large consumers with their own switchyard.

Typical system levels in this range are 66 kV, 110 kV and 132 kV; 150 kV and above lie outside the upper limit. Manufactured in Japan by Hasegawa Electric, it is supplied by HASEGAWA Türkiye, the official HASEGAWA distributor in Türkiye, to customers across Europe, and we help you choose the right voltage class for your installation.

Where is it used?

• 66 kV – 132 kV switchyards: confirming the absence of voltage on line and transformer feeders after the disconnectors have been opened, before the earthing switches are closed.
• Industrial main intake substations: planned shutdown maintenance at steel, chemical or mining sites supplied at high voltage.
• Maintenance contractors: teams travelling to different sites use the same stick and only change the detector head to match the voltage class.
• Post-fault checks: on-site verification of the busbar status before any intervention following a protection trip.

HST-138V, HST-35V or HST-550V?

The three models in the series are identical in indication, water resistance and battery. They differ only in voltage class:

	HST-35V	HST-138V	HST-550V
Operating voltage (AC)	6 kV – 35 kV	66 kV – 138 kV	210 kV – 550 kV
Typical system level	10 kV – 33 kV distribution	66 kV, 110 kV, 132 kV	220 kV – 400 kV transmission
Indication	70 dB sound + red LED	70 dB sound + red LED	70 dB sound + red LED
Water resistance	IPX4 equivalent	IPX4 equivalent	IPX4 equivalent

Levels between 138 kV and 210 kV, such as 150 kV, are not covered by any of these three models. For these, the hot stick HST-170 with an AC 60 kV – 195.5 kV range is suitable. If you are looking for an alternative with stronger indication in the same 66 kV – 138 kV class, the HWB-138 is worth considering.

Technical specifications

• Operating voltage: AC 66 kV – 138 kV, 50/60 Hz
• Alarm: intermittent sound of at least 70 dB and red LED (visible at 8000 lx)
• Protection: IPX4-equivalent water resistance
• Operating temperature: −10 °C … +50 °C
• Power supply: 2 × LR44 (1.5 V)
• Connection: mounted on a common stick via a universal joint
• Accessory: storage case

Limits of use and safety

The HST-138V is not used in MV installations below 66 kV or at transmission levels above 138 kV; a test made in the wrong class can give a misleading result. Before starting, check that the detector works at a point known to be live or with a compatible tester, and repeat the check at the end of the job. Approach distances are large at this voltage level; the length and insulation class of the stick must be suitable for the system voltage, and the stick must not be used while damp or dirty. Once the absence of voltage has been verified, the work location must be earthed on both sides; details are in our earthing guide.

Why buy from HASEGAWA Türkiye?

• For operators running both 66 kV – 132 kV and 150 kV installations, we can configure the HST-138V and HST-170 in the same quotation
• Preliminary assessment of compatibility with your switchyard team's existing sticks
• Supplied directly by the official HASEGAWA distributor in Türkiye, with a commercial invoice