EB-60X Installation & Service Manual |
Motor Data Package
TOUT
Tc =
1 - e-ton / Duty cycle X TCTP
/ TCTP
-ton
1 - e
where, duty cycle = ton/(ton + t
OFF
)
T
OUT
= output torque
Tc = continuous torque at operating speed
t
ON
= time on
TCTP = thermal time constant for peak power of motor
This equation expresses operating torque as a function of ON time. It also breaks the
operating cycle down into individual periods of ON time and OFF time. Substituting for duty
cycle and solving for t
OFF
), the above equation yields Equation 2 (EQ-2):
(EQ-2)
toff = - TCTP 1n 1 -
/ TCTP
-ton
1 - e
Tc
2
TOUT
2
-ton
*
For a specific output torque and a given ON time, the required OFF time is known. This OFF
time is required so the motor cools sufficiently and does not exceed its thermal limits. The
calculated OFF time should proceed the initial ON time to ensure that the ultimate
temperature is not surpassed on the first cycle.
It may also be useful to calculate a time to ultimate experience temperature based on a one-
time excursion from ambient temperature. Consider the following pair of equations:
R
T
(EQ-3) T Actual Above Ambient =
R Rated Above Ambient
TOUT
2
Tc
(EQ-4)
Rated =
TR
TR Ulitmate (1 - e _ )
where = time / TCTP
substitute (3) into (4) and obtain
(1 - e )
T
TOUT
2
Tc
= TR Ulitmate
-t/TCTP
actual
R
To find the time to ultimate temperature, set T
R
actual = T
R
ultimate and solve for t. This
yields the following equation:
Summary of Contents for EB-9207
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