Cooling; Operating Voltage - Lab.gruppen PLM 20K44 Operation Manual

3. Installation

3.3. Cooling

3.3.1. Overview
The PLM+ Series devices use a forced-air cooling system with airflow from front to rear, allowing high continuous
power levels without thermal problems. Front-to-rear airflow is preferable as air at the front of a rack is cooler than
that at the rear in nearly all situations; never attempt to reverse the airflow. The operation of the PLM+'s cooling
system is dependent on front-to-rear airflow; it will not function effectively with external airflow in the opposite
direction.
Make sure an adequate air supply is provided in front of the PLM+, and that the rear of the PLM+ has sufficient
space to allow air to escape. If the PLM+ is rack-mounted, never operate the unit with any front or rear rack doors
or covers in position. It is recommended to keep the ambient temperature around the PLM+ as cool as possible.
An increased temperature can have a significant negative impact on the expected lifetime on the components
inside the PLM+.
Note: Fit solid blanks (not ventilation blanks) to unused rack spaces to ensure effective air circulation.
Leaving gaps in between items of equipment degrades the effectiveness of forced-air cooling.
If installing one or more PLM+ Series devices in a rack with other fan-cooled equipment, be sure that all the
other equipment also uses front-to-rear airflow for cooling. If this precaution is not observed, there is a risk of
overheating, as units with the reverse airflow will be drawing in air which has already been heated by the PLM+s.
3.3.2. Temperature Sensing and Protection
The PLM+ is equipped with a sophisticated temperature sensing system which protects it from any overheating
which may occur as a result of inadequate ventilation.
Note: Always ensure the dust filters behind the detachable front panel are clean to ensure maximum
possible airflow.

3.4. Operating Voltage

The label adjacent to the mains (AC) input connector indicates the AC mains voltage for which the device is wired
and approved. Both PLM+ models incorporate a universal power supply operating from 80 to 265 V. Only connect
the mains cable (AC cord) to an AC source of the voltage shown on the label.
The PLM+ uses primary switching, which means the mains power is rectified on the primary side of the
transformer. This makes the power supply insensitive to mains frequency variation, and it will operate normally on
line frequencies from 45 to 75 Hz.
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PLM+ SERIES Operation Manual rev 1.0.0