HVC-750N3 DC 750 V Third Rail Voltage Detector

HASEGAWA HVC-750N3 is a DC third rail voltage detector designed to verify absence of voltage on the third rail and on DC 600 V, 750 V and 1500 V lines of metro and light-rail systems. Power and track maintenance teams at rail operators use it to check before starting work on the rail or line during the night maintenance window.

With an alarm threshold of DC 300 V ±20 V to earth, it gives a clear warning even on systems with a low nominal voltage. The red LED and buzzer signal the presence of voltage, while the 0–1999 V DC voltage display shows in figures the residual voltage as it falls after disconnection. At approximately 1.4 kg it is the light member of the series. Manufactured in Japan, it is supplied by HASEGAWA Türkiye, the official HASEGAWA distributor in Türkiye.

How does a third rail voltage detector work?

The earth lead is connected to the running rail or to the earth point specified by the operator; when the green LED lights, the earth connection is sound. The contact tip is then touched against the conductor rail or conductor. If the voltage to earth exceeds the threshold of around DC 300 V, the red LED lights and the buzzer sounds; at the same time the voltage value can be read on the display.

This design is particularly useful for:

• Verifying that the conductor rail has been switched off before night maintenance
• Following the decay of residual voltage on the rail after the feed is disconnected
• Checking with a single unit at operators with DC 600 V, 750 V and 1500 V systems
• Confirming section isolation after a fault

HVC-750N3 or HVC-1.5N3?

	HVC-750N3	HVC-1.5N3
Operating voltage	DC 600 V / 750 V / 1500 V	DC 1500 V
Alarm threshold (to earth)	DC 300 V ±20 V	DC 750 V ±50 V
Test output voltage	DC 500 V ±100 V	DC 1000 V ±200 V
Weight	Approx. 1.4 kg	Approx. 2.3 kg
Warning	Red LED + buzzer	Red LED + buzzer

If you work on a network with several DC voltage levels, the HVC-750N3 covers a wider range of applications. If the team works only on DC 1500 V catenary, the HVC-1.5N3 with its threshold dedicated to that level may be preferred. For monorail systems there is also the HVC-1.5N3M.

Technical specifications

• Operating voltage: DC 600 V / 750 V / 1500 V
• Starting voltage: DC 300 V ±20 V (to earth)
• Voltage display: 0–1999 V DC, 1 V resolution, accuracy ±5% ±5 V
• Voltage warning: red LED and buzzer; earth lead check: green LED
• Buzzer volume: High ≥75 dB, Medium 55–70 dB, Low ≤50 dB (at 1 m)
• Test output voltage: DC 500 V ±100 V
• Dielectric strength: AC 4 kV, 1 minute; leakage current ≤1 mA
• Battery: 4 × R6 / LR6 (1.5 V); operating temperature 0 °C … +50 °C

Limits of use and safety

Like the other models in the series, the HVC-750N3 does not detect negative potential; a "no alarm" result on a conductor at negative polarity must not be accepted as safety confirmation. Before use, run the test function and check the batteries and the earth lead. Do not start measuring until the earth connection has been confirmed by the green LED.

Once absence of voltage has been confirmed, the line or rail must be earthed for the duration of the work with a suitable railway earthing hook. For maintenance and periodic checks of the detector, see our article Voltage Detector Periodic Inspection; for the general procedure on rail systems, our guide to catenary voltage testing.

Why buy from HASEGAWA Türkiye?

• HVC model recommendations by voltage level for metro and light-rail operators
• A single quotation for multi-unit orders for depot and maintenance teams
• Support with user training and technical documentation, and a commercial invoice