Additional features
Function available	With integrated light sensor
[Ue] Rated operational voltage	230 V
[In] Rated current	10 A
Switching power in W	2300
Light sensitivity	2...300 lux
Contact type and composition	1 make contact (NO)
Material	Polycarbonate glossy
Contractual warranty
Warranty (in months)	18
Main features
Product series	Merten
Product or component type	Dusk switch
Hue	Light grey
Mounting
Degree of protection (IP)	IP54
Packaging units
VPE 1 type	PCE
Number of devices per package	1
VPE 1 height	5,500 cm
VPE 1 width	8,500 cm
VPE 1 length	10,700 cm
Packaging weight (Lbs)	198,000 g
VPE 2 type	CAR
VPE 2 quantity	35
VPE 2 height	19,400 cm
VPE 2 width	30,900 cm
VPE 2 length	40,200 cm
VPE 2 weight	7,318 kg

The Merten ARGUS dusk timer, type 544890, is a weather-protected surface-mounted device for the automatic control of lighting systems. The device combines the functions of a dusk switch and a timer in a compact housing made of impact-resistant polycarbonate in light grey colour. It is suitable for use outdoors or in damp indoor areas, as it has protection class IP54, meaning dust-tight and splash-proof. The integrated light sensor detects ambient lighting and switches the lighting on or off accordingly, with the switching threshold adjustable between 2 and 300 Lux.

Applications
This device is suitable for the automated control of outdoor lighting, such as in driveways, garages, courtyard areas, or on buildings where time- and light-dependent lighting is required. The dusk timer is particularly advantageous in areas where manual operation is impractical or energy saving is desired. The automatic adjustment of the timer to ambient lighting ensures that the lighting functions correctly regardless of the season or day length.

Functions and equipment in detail
The device offers three operating modes: dusk function, automatic function, and semi-automatic function. In dusk mode, the lighting is switched on in the evening when the set dusk threshold is reached and switched off again in the morning. In automatic mode, the lighting is switched on in the evening at dusk and switched off at a pre-set time (e.g. 23:00) and switched on again in the morning at another pre-set time (e.g. 5:00), then switched off again when the dusk threshold is reached. In semi-automatic mode, the lighting is switched on in the evening at dusk and switched off at a pre-set time, without switching on again in the morning. An integrated special function ensures automatic adjustment of the timer to ambient lighting, so no manual setting is required.

Technology explained simply
The switch operates with a relay that has a u-contact (make contact). The maximum switching capacity is 2300 VA at an operating voltage of 230 V and a rated current of 10 A (cos φ = 0.6). The connection terminals are designed for rigid conductors with a cross-section up to 2.5 mm². The switching capacity is designed for various load types: incandescent lamps up to 2300 W, halogen lamps up to 2000 W, and capacitive loads up to 140 μF. For inductive loads, an external capacitor (item 542895) can be connected to reduce switching surges.

Compatibility and accessories
The device is compatible with the accessory capacitor 542895, which is recommended for switching inductive loads. The connection terminals allow for a secure connection with standard cables. Installation is carried out on a wall, ideally at a location not directly illuminated by the lighting to avoid false triggering. The openings in the housing allow for wall mounting and cable routing from below or above.

Installation and mounting
Mounting is done by securing the housing to the wall using the provided openings, with the marking “OBEN” pointing upwards. The opening for condensate water drainage can be opened or closed depending on the environment. After connecting the cables, the device is inserted into the housing and secured with the two front screws. The setting of the dusk threshold, evening and morning switch-off times is done using the provided adjustment screws.

Advantages in operation
The dusk timer reduces energy consumption by automatically switching the lighting on and off. The automatic time adjustment to day length ensures reliable operation without manual intervention. The robust, impact-resistant polycarbonate housing and protection class IP54 ensure a long service life even under harsh environmental conditions. The large connection space facilitates installation and maintenance.