LTDVE8CH– INSTRUCTIONS MANUAL
7
interface and an Ethernet interface (see
chapter 8
).
6. Mechanical fixing
The controller must be mounted on a DIN rail. Allow free flow of air around the unit. The controller
has an IP rating of 20 and should be installed so that moisture and dirt cannot enter it.
An enclosure may also be required for other parts of the system such as power supplies. That
enclosure would provide both mechanical and environmental protection in industrial applications.
7. Heat dissipation
The controller integrates several linear circuits to produce the constant current outputs. This means
that it generates heat which needs to be dissipated. The operating temperature range is 0 °C to 40 °C.
The controller can approximately dissipate the following average powers:
30 W at 25 °C (about 3.8 W per channel)
25 W at 40 °C (about 3.1 W per channel)
A simple way to estimate the maximum average power the controller can dissipate is by applying the
following formula:
DissipablePower
[W] = (TempHeatsink [°C] – TempAmbient [°C]) / ThResistance [°C/W]
Where:
DissipablePower
is the maximum average power the controller can dissipate
TempHeatsink
is the maximum temperature of the controller heatsink
TempAmbient
is the actual temperature of the ambient where the controller is placed
ThResistence
is the thermal resistance between the heatsink and the ambient
For the LTDVE series the
ThResistance
parameter is about 1.91 °C/W.
The maximum permissible controller heatsink temperature is 90 °C. If the heatsink temperature rises
above 90 °C, the controller switches off all the output channels. Output channels are then reactivated
once temperature falls below 80 °C.
If the average power that must be dissipated is greater than the previously stated value, a different
and more efficient cooling system is required. Solutions could be the use of a cooling fan (active
cooling system) or the use of a bigger heatsink (passive cooling system).
The controller can be powered with supply voltages between 24 V and 48 V. This allows a large
number of different lights to be efficiently driven. Take care of the actual supply voltage when
calculating the generated heat.
7.1. Calculating generated heat per channel
For a pulsed output, the average power that is transformed to heat and then must be dissipated can be
calculated using the following formula:
Heat [W] = LightCurrent [A] * (SupplyVoltage [V] – LightVoltage [V]) * DutyCycle [·]
Where:
LightCurrent
is the illuminator operating current
LightVoltage
is the illuminator operating voltage
