Power Dissipation - Racal Instruments 1260 VXI Manual

1260-152/172 User Manual
Power
Dissipation
Racal Instruments Ó2003
Shock
Vibration
Bench Handling
Cooling
Temperature
Operating
Non-operating
Relative Humidity
Altitude
Operating
Non-operating
Power Requirements
+5VDC
Weight
MTBF
Dimensions
While the cooling of the Adapt-a-Switch carrier is dependent upon
the chassis into which it is installed, the carrier can normally
dissipate approximately 100 W. Care must be taken, then, in the
selection and loading of the plug-in modules used in the carrier. It
is not possible to fully load the carrier, energize every relay, and
run full power through every set of contacts, all at the same time.
In practice this situation would never occur.
To properly evaluate the power dissipation of the plug-in modules,
examine the path resistance, the current passing through the relay
contacts, the ambient temperature, and the number of relays
closed at any one time.
For example, if a 1260-152/172 module (containing 17 relays) has
all relays closed, passing a current of 0.5A, then:
Total power dissipation =
2
[(current) * (path resistance) * 17 ] + (quiescent power)
By substituting the actual values:
30g, 11ms, ½ sine wave
0.013 in. P -P , 5-55Hz
k k
4 in., 45°
See 1260-100 cooling data
0°C to +55°C
-40°C to +75°C
85% ± 5% non-condensing at
< 30°C
10,000 feet
15,000 feet
150mA + 40mA per energized relay
(850mA Max.)
9oz. (0.26kg)
>300,000 hours (MIL-HDBK-217E)
4.5"H X 0.75"W X 9.5"D
Module Specification 1-3