Model ELV-841

The Hagner ELV-841 Light Sensor is designed for continuous, stationary outdoor measurement of illuminance. It consists of a Vλ-filtered and cosine corrected detector and an amplifier with regulated current output (4-20 mA). The case is watertight, fitted with a thermostatocally controlled internal anti-condensation heater. Measuring range is specified with order (e.g. 0 - 1,500 lux). 

The Hagner Light Sensor ELV-841

The Hagner Light Sensor ELV-841 consists of a detector and an amplifier with regulated current output characteristic. The case is watertight, fitted with a thermostatically controlled internal anti-condensation heater. The ELV-841 light sensor measures light or other radiation with very high accuracy. The regulated current output characteristic allows it to be connected to long lines, e.g. to a remote data logger or computer. The ELV-841 is intended for continuous, stationary use outdoors or under extremely wet conditions. (A simpler version is also available for indoor conditions.)


Typical applications for the ELV-841 include control of artificial lighting, operation of shades and recording of light quantities. The design of the sensor is determined by the application for which it is intended, e.g.: Control of street lighting in vehicle tunnels, underpasses etc. For this application, the sensor is filtered to provide the same spectral response as the human eye (CIE, Vλ curve, with cosine correction) and internal case heating. For meteorological measurement and recording, with correction either to Vλ or special filtration, with or without cosine correction, and with internal heating. Special filters can be supplied for such applications as infra-red, photosynthesis or narrow-band measurements. When used indoors, in factories and offices no internal heating is required. The combinations are endless. The ELV-841 can also be modified so that the dome is replaced by an optical system for luminance measurement (ELV-841-L only for indoor use).

Tecnhical data

Detector  Silicon photodiode, Vλ-filtered and cosine corrected
(in standard version)
Measurement range Specified with order (e.g. 0 - 20,000 lux)
Output signal 4 - 20 mA DC
Max. external resistance 800 ohm
Accuracy Better than +/- 3%
Power supply 24 volt AC (min. 36 VA)
Temperature range -40°C - +50 °C
IP  65
Heater  8.5 W
Heater  PTC heating
Dimensions 100 x 100 x 90 mm
(incl. dome but excl. mounting brackets and cable entrance)
Weight 0.5 kg
Connection 3 meters long wire with terminal block at the end (longer cables on request)


ELV-841 Connection instructions

4 Way terminal block

1 minus

2 output signal 4-20 mA

3 power supply 24 VAC

4 power supply 24 VAC

Please note: Never connect any of the output wires with the power supply