Instruction manual

Specifications Characteristics
10 - 6
10.1.4
Dynamic braking
If an alarm, an EMERGENCY OFF or a loss of power occurs, then the servo motor is switched
directly to an integrated dynamic braking unit in the amplifier and is braked. In Fig. 10-5 the delay
curve is presented
.
The following formula can be used to calculate the approximate coasting distance:
L
max
: Maximum coasting distance [mm]
V
0
: Machine's fast feed speed [mm/min]
J
M
: Servo motor inertia moment [kgcm
2
]
J
L
: Load inertia moment converted into equivalent value on servo motor shaft [kgcm
2
]
τ: Brake time constant [s]
t
e
: Delay time of control section (There is internal relay delay time of about 30ms) [s]
S000657C
Fig. 10-5: Dynamic brake operation diagram
b
CAUTION:
Use the dynamic brake for the servo amplifiers MR-J2S-10B to MR-J2S-200B and MR-
J2S-60B4 to MR-J2S-200B4 only up to a maximum ratio of the mass moment of inertia
of 30, for the servo amplifiers MR-J2S-350B and MR-J2S-350B4 up to an inertia of mass
ratio of 16 and for the servo amplifiers MR-J2S-500B, MR-J2S-700B, MR-J2S-500B4
and MR-J2S-700B4 up to an inertia of mass ratio of 15. If these figures are exceeded
the integrated dynamic brake may overheat (fire risk). If there is a probability that the
figure may be exceeded, then please contact your sales representative.
V
0
t
t
e
Emergency stop (EMG)
ON
OFF
Machine speed
Time constant τ
L
max
V
0
60
------
t
e
τ 1
J
L
J
M
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