CHARACTERISTICS FOR OHMITE AXIAL-LEADED RESISTOR MATERIALS

The table shows the characteristics of the bulk ceramic materials used for Ohmite axial-leaded resistors.

Characteristic Type SP Type AS / Type BA
MATERIAL CHARACTERISTICS
Operating temperature1) -55 to +350°C
(-67 to 662°F)		 -55°C to +230°C
(-67 to 446°F)
Resistance temperature
coefficient		 + 0.2 to - 0.08%/°C +0.0 to -0.08%/°C
Voltage coefficient
Max. % per kilovolt
per inch active length		 -1.0% -1.0%
Short time overload 2) +/-5% +/-2%
Load life
Max. % change after 1000 hrs.
at rated power		 +/-5% +/-5%
Thermal shock
Max. change after 10 cycles
-55°C to +125°C		 +/-3% +/-3%
Moisture resistance
Max. % change when tested
per MIL-STD-202, Method 103		 +/-5% +/-5%

1) When required, type SP material can withstand short periods of use at red-heat conditions, i.e. up to 550-600°C (1022-1112°F)

Physical properties (nominal)

  Type SP resistors Type AS / Type BA resistors
Density 2.2 - 2.4 gm/cc 2.2 - 2.6 gm/cc
Specific heat 0.24 - 0.26 cal/gm °C 0.23 - 0.25 cal/gm °C
Thermal conductivity 0.14 - 0.16 cal/cm -°C - sec 0.003 - 0.006 cal/cm -°C - sec

Power rating curves

Power-rating-curves BA AS SP.gif


2) Max. change after 10 cycles of 10 times rated power 5 sec. On, 90 sec. Off.