2 - Fagor Automation

5.6 Ballast resistor selection guide
Calculate the value of:
Wm Energy generated by the braking of each system motor.
Pe Rms power generated by all braking of all the motors
throughout a complete duty cycle.
Based on the following formulae:
W m
W p
where:
=
=
1 2 n
W
p
+ -- J -------------
2 t 60
2
Ws
mgh Jt Total inertia of the servo system (motor + mechanics) in kg.m².
n Turning speed of the motor when the braking starts in rpm.
Wmi Energy of each braking during a cycle of time T in Ws.
Wp Potential energy lost by the machine mass while braking (only on
non-compensated axes) in Ws.
ti Braking time (in seconds) when the Wmi energy is generated.
T Time (in seconds) in a full cycle.
Dh Height (in m) lost while braking.
Wmx Maximum energy among all the Wm.
Pmx Maximum power generated by all the braking, given by the maximum
value among all the (Wmi / ti) quotients of each braking in kW.
P e
W
mi
P ----------mx
=
t
i max
=
kW
2
W
mi
----------
t
i
i
-------------------- w T
Selection criteria
SELECTING CRITERIA
Ballast resistor selection guide 5.
DDS
HARDWARE
Ref.1307
229