9. SPECIFICATIONS
9－52
(2) Instantaneous resistance of dynamic brake
When the load inertia (J
L
) substantially exceeds the applicable load inertia, dynamic brake resistance
may abnormally increase, causing an overheating alarm or damage of the dynamic brake resistance.
Consult with us if such operating conditions are assumed.
The energy E
RD
consumed by the dynamic brake operation at a single time is represented by the
following expression.
E
RD
= × { (J
m
+ J
L
) × N – I • T
L
}
Rφ : Motor phase winding resistance (Ω)
J
m
: Motor inertia (kg･m
2
)
J
L
: Load inertia (calculated in terms of motor shaft) (kg･m
2
)
N : Motor speed at the feed speed V (min
－
1
)
I : Overall slowing-down revolution angle (rad)
T
L
: Load torque (N･m)
Be sure to keep E
RD
below the value in the following table.
Table 9-15
Amplifier model No. E
RD
(J)
PY2A015
PY2E015
360
PY2A030
PY2E030
360
PY2A050 1330
(3) Allowable frequency of dynamic brake
The allowable frequency (frequency of turning main circuit power supply on or off) of the dynamic brake
should be a maximum of 10 times per hour and 50 times per day under the applicable load inertia and at
the maximum speed.
As a rule of thumb, a six-minute interval shall be provided between the preceding and
succeeding dynamic brake operations. If more frequent use is anticipated, the motor
speed must be substantially reduced.
The following expression can be used to compute an appropriate speed.
6 minutes
(Rated motor speed/ Maximum motor speed when operating)
2
When the energy consumed by dynamic brake resistance during one dynamic braking
exceeds the specified value indicated in Table 9-15, the dynamic brake may be damaged.
Consult us if such operating conditions are anticipated.
(The dynamic brake will not be damaged if the load is within the range of the applicable load
inertia.)
2π
60
2.5
Rφ + 2.5
1
2
2
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