4Dynamic Braking - Mitsubishi Electric MELSERVO MRJ2S-B Instruction Manual

Specifications
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 .
Fig. 10-5: Dynamic brake operation diagram
The following formula can be used to calculate the approximate coasting distance:
L
=
max
L : Maximum coasting distance [mm]
max
V : Machine's fast feed speed [mm/min]
0
J : Servo motor inertia moment [kgcm
M
J : Load inertia moment converted into equivalent value on servo motor shaft [kgcm
L
τ
: Brake time constant [s]
t : Delay time of control section (There is internal relay delay time of about 30ms) [s]
e
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.
10 - 6
Emergency stop (EMG)
OFF
Machine speed
⎧ ⎫
V
J
⎛ ⎞
0
τ × L
------ t ⎨ ⎬
1
+ + ------ -
⎝ ⎠
e
60
J
⎩ ⎭
M
ON
t
e
2
]
Characteristics
Time constant τ
t
S000657C
2
]