ABOUT ELMA-MEKTRON | EMPLOYMENT | CONTACT US | REQUEST QUOTATION

2008

Thermal Management

DESIGN INTEGRITY

USEFUL DESIGN DATA

Convection Cooled ATR Spec

Conduction Cooled ATR Spec

Standard ATR Dimensions

Typical ATR Weights

Mechanical Fragility Factors

Pressure/Temp Variations

Thermal Management

PROBLEM SOLVING INNOVATIONS

TABLE KEY

Permissable operation up to 55°C

Requires reduced ambient Temperature

Out of thermal range

The chart below will enable you to convert air flow volume between cubic metres per hour, cubic metres per minute, litres per second and cubic feet per minute (CFM).

Volume Conversion Chart

There are numerous factors that have an effect on the thermal management of an enclosure and below are a few tables and charts that will assist with this most important task.

The tables below will allow you to assess the effect of the power dissipation of various power supply wattages in a variety of standard ATR enclosure sizes each with three different ATR enclosure formats i.e. radiated, forced-air and base plate. Having made your selection the ‘Table Key’ will indicate whether your choice of PSU is suitable for the enclosure size or if further thermal design action is needed for your application.

Also included below is a ‘Volume Conversion Chart’ that will enable you to convert air flow volume between cubic metres per hour, cubic metres per minute, litres per second and cubic feet per minute (CFM) and an ‘Effective Air Flow / Heat Dissipation’ chart that will assist in the use of air baffle boards in unpopulated positions in order to maximising the air flow across the system boards and so eliminate thermal management problems.

¼ ATR SHORT

POWER IN WATTS

CHASSIS FORMAT

Radiated

Forced Air

Base Plate

25	50	75	100	125	150	175	200	225	250	275	300	325	350	375	400	425	450	475	500	525	550	575	600	625	650	675

½ ATR SHORT

POWER IN WATTS

CHASSIS FORMAT

Radiated

Forced Air

Base Plate

25	50	75	100	125	150	175	200	225	250	275	300	325	350	375	400	425	450	475	500	525	550	575	600	625	650	675

¾ ATR LONG

POWER IN WATTS

CHASSIS FORMAT

Radiated

Forced Air

Base Plate

25	50	75	100	125	150	175	200	225	250	275	300	325	350	375	400	425	450	475	500	525	550	575	600	625	650	675

1 ATR SHORT

POWER IN WATTS

CHASSIS FORMAT

Radiated

Forced Air

Base Plate

25	50	75	100	125	150	175	200	225	250	275	300	325	350	375	400	425	450	475	500	525	550	575	600	625	650	675

1 ATR LONG

POWER IN WATTS

CHASSIS FORMAT

Radiated

Forced Air

Base Plate

25	50	75	100	125	150	175	200	225	250	275	300	325	350	375	400	425	450	475	500	525	550	575	600	625	650	675

1 ½ ATR SHORT

POWER IN WATTS

CHASSIS FORMAT

Radiated

Forced Air

Base Plate

25	50	75	100	125	150	175	200	225	250	275	300	325	350	375	400	425	450	475	500	525	550	575	600	625	650	675

1 ½ ATR LONG

POWER IN WATTS

CHASSIS FORMAT

Radiated

Forced Air

Base Plate

25	50	75	100	125	150	175	200	225	250	275	300	325	350	375	400	425	450	475	500	525	550	575	600	625	650	675

Effective Airflow Chart - cubic feet per minute against heat dissipation

Caution! Unused Slots in Your System
Air naturally follows the path of least resistance, therefore in systems sparsely populated with boards it is important to pay particular attention to maximising the air flow across them.

To ensure that thermal management problems are eliminated, use of air baffle boards in unpopulated positions should be seriously considered.

Air flow across individual board locations can be measured with a thermal anemometer.

As a rule of thumb, 160mm deep boards spaced on a 0.8 inch (20.3mm) pitch, such as VME for example, and dissipating 35 to 40 watts require an air velocity of 150 to 200 l.f.m. (linear feet per minute) or 0.76 to 1.01 m/s (metres per second) to maintain less than a 10°C average temperature rise.

Conversion of linear feet per minute to metres per second: l.f.m. divided by 196.8 = m/s.

< back

Tel: +44 (0)1234 838822

Fax: +44 (0)1234 836650

Email: info@elma-mektron.co.uk