Specifications

Reference Manual
MHM-97408, Rev. 2
June 2008
C-7
CSI 9420
Use the following relationships to determine T
rise
.
•T
rise
= 65 °C + serv_fact_temp; for class A insulation
•T
rise
= 85 °C + serv_fact_temp; for class B insulation
•T
rise
= 110 °C + serv_fact_temp; for class F insulation
•T
rise
= 130 °C + serv_fact_temp; for class H insulation
•T
rise
= 150 °C + serv_fact_temp; for class N insulation
serv_fact_temp =
• 5 for service factor of 1.15 or greater
• -5 for either open or TEFC motors, and service factor of 1.0
• 0 for either totally enclosed non-ventilated (TENV) motors or motors
with encapsulated windings, and service factor of 1.0
If elevation > 3300 ft (1000m) then,
T
rise
= T
rise
[1-((altitude (units of ft) - 3300)/33,000)]
If T
a
is less than or equal to 40 °C (or unknown), then
T
w
= T
rise
+ 40 °C
If T
a
> 40 °C, then
T
w
= T
rise
+ 40 °C - (T
a
- 40 °C)
Again, if T
a
is unavailable assume T
a
is less than 40 °C.
Next, calculate the generic alert thresholds based on the estimated winding
temperature, T
W
.
T
f_fault
= Fault level alarm temperature (°C) of the motor skin (frame)
T
f_maintenance
= Maintenance level alarm temperature (°C) of the motor skin
T
f_advisory
= Advisory level alarm temperature (°C) of the motor skin
Alarm levels
For open drip proof (ODP) motors:
T
f_fault
= 35.5366*Ln(T
w
) - 91.1571
For totally enclosed motors:
T
f_fault
= 37.2028*Ln(T
w
) - 102.8868
For all motors,