EB-60X Installation & Service Manual |
Motor Data Package
(EQ-5)
- TCTP 1n
TOUT
2
Tc
1 -
t max
where: t = max on time
TCTP = thermal time constant of motor
Tc = continuous torque of the motor at the particular operating speed
T
OUT
= operating torque
This gives the maximum ON time for a given operating torque beginning at ambient
temperature. Examination of this equation reveals that as T
OUT
approaches Tc, t approaches
infinity. This is expected since we can theoretically operate the motor indefinitely at
continuous torque without exceeding its thermal limits. EQ-5, with EQ-2, define the motor’s
operating time limits.
Example #1
An EB-606-B has torque vs. speed performance characteristics described in the performance
curve, EB-606-B
PC- 26619. The motor is operating intermittently at 4150 rpm with a torque
of 47.1 lb-ft.
FIND:
a) maximum ON time without exceeding ultimate temperature
b) the required OFF time for an ON time of 4 seconds
GIVEN: T
OUT
= 47.1 lb-ft
From performance curve, EB-606-B
PC- 26619 the continuous torque at 4150 rpm is
obtained.
Tc = 18.0 lb. ft.
From the Specifications CD-27028:
TCTP = 16 min.
a) The maximum ON time is found from EQ-5:
- TCTP 1n
TOUT
2
Tc
1 -
t max
TCTP = 16 min.
Tc = 18.0 lb-ft
T
OUT
= 47.1 lb-ft
t
= - 16 min 1n
47.1
2
18.0
1 -
max
t
MAX
= 16 min. 1n [0.8540]
t
MAX
= 16 min (0.158)
t
MAX
= 2.52 min.
If the motor has an ON time greater than 2.52 minutes, it exceeds the thermal limits.
Summary of Contents for EB-9207
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