Product Description
The QT20.481 is a DIN-rail mountable power supply for three-phase mains systems, which provides a
floating, stabilized and galvanically separated SELV/PELV output voltage.
The QT20.481-C1 device is the same as the QT20.481 but with conformal coated pc-boards.
Intended Use
This device is designed for installation in an enclosure and is intended for commercial use, such as in
industrial control, process control, monitoring, measurement equipment or the like.
Do not use this device in equipment, where malfunctioning may cause severe personal injury or
threaten human life without additional appropriate safety devices, that are suited for the end-
application.
If this device is used in a manner outside of its specification, the protection provided by the device may
be impaired.
Installation Instructions
Install device in an enclosure providing protection against electrical, mechanical and fire hazards.
Install the device onto a DIN-rail according to EN 60715 with the input terminals on the bottom of the
device. Other mounting orientations require a reduction in output current.
Make sure that the wiring is correct by following all local and national codes. Use appropriate copper
cables that are designed for a minimum operating temperature of 60°C for ambient temperatures up to
+45°C, 75°C for ambient temperatures up to +60°C and 90°C for ambient temperatures up to +70°C.
Use ferrules for wires on the input terminals. Ensure that all strands of a stranded wire enter the
terminal connection.
The device is designed for pollution degree 2 areas in controlled environments. No condensation or
frost is allowed.
The enclosure of the device provides a degree of protection of IP20. The enclosure does not provide
protection against spilled liquids.
The device is designed for overvoltage category II zones. Below 2000m altitude the device is tested
for impulse withstand voltages up to 4kV, which corresponds to OVC III according to IEC 60664-1.
The device is designed as “Class of Protection I” equipment according to IEC 61140. Do not use
without a proper PE (Protective Earth) connection.
The device is suitable to be supplied from TN, TT or IT mains networks. The continuous voltage
between the input terminal and the PE potential must not exceed 400Vac. The device is not designed
to be used on corner grounded delta systems.
A disconnecting means shall be provided for the input of the device.
The device is designed for convection cooling and does not require an external fan. Do not obstruct
airflow and do not cover ventilation grid!
The device is designed for altitudes up to 5000m (16400ft). Above 2000m (6560ft) a reduction in
output current is required.
Keep the following minimum installation clearances: 40mm on top, 20mm on the bottom, 5mm left and
right side. Increase the 5mm to 15mm in case the adjacent device is a heat source. When the device
is permanently loaded with less than 50%, the 5mm can be reduced to zero.
The device is designed, tested and approved for branch circuits up to 20A without additional protection
device. If an external fuse is utilized, do not use circuit breakers smaller than 6A B- or 3A C-
Characteristic to avoid a nuisance tripping of the circuit breaker.
The maximum surrounding air temperature is +70°C (+158°F). The operational temperature is the
same as the ambient or surrounding air temperature and is defined 2cm below the device.
The device is designed to operate in areas between 5% and 95% relative humidity.
Installation Instructions for Hazardous Location Areas
The device is suitable for use in Class I Division 2 Groups A, B, C, D locations.
Substitution of components may impair suitability for this environment.
Do not disconnect the device or operate the voltage adjustment unless power has been switched off or
the area is known to be non-hazardous.
Functional Description
The output is electronically protected against no-load, overload and short circuit and can supply any
kind of loads, including unlimited inductive or capacitive loads.
Do not apply returnvoltages fromthe loadtothe output terminals higher than 58V.
The output voltage can be adjusted with a small flat-blade screwdriver behind the flap on the front.
The green DC OK LED reports an output voltage above 90% of the adjusted voltage of a running
device.
The DC OK relay monitors the output voltage and the contact is closed when the DC OK LED is on.
Contact ratings: 60Vdc 0.3A, 30Vdc 1A, 30Vac 0.5A for resistive loads.
The red overload LED is on when the output voltage falls below 90% of the adjusted value or in case
of a short circuit in the output or too high temperature. Input voltage is required.
The device is equipped with an over-temperature protection. In case of a high temperature, the output
shuts down and starts automatically again after cooling off.
Devices can be paralleled to increase the output power. The ambient temperature is not allowed to
exceed +60°C. The output voltage shall be adjusted to the same value (±100mV) with the same load
conditions on all devices, or the devices can be left with the factory settings. If more than three
devices are connected in parallel, a diode, fuse or circuit breaker with a rating of 15 or 16A is required
on each output.
Same devices can be connected in series for higher output voltages. It is allowed to connect as many
devices in series as needed, providing the sum of the output voltage does not exceed 150Vdc.
In case of an internal defect, a redundant circuit limits the maximum output voltage to 60V. The output
shuts down and automatically attempts to restart.