Fagor DDS Series Hardware Manual page 223

5.5 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:
2 n
1
------------- -
W m = W p + -- -  J t
60
2
m g h
W p =  
where:
Jt Total inertia of the P ower D rive S ystem (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 maxi-
mum value among all the (Wmi / ti) quotients of each braking in kW.
P mx
2

 
Ws

i
P e = -------------------- -
W mi
 
----------- -  
=   kW
t i
 
max
   Selection criteria
5.
2
W mi
----------- -
t i
 
w
T
HARDWARE
DDS
Ref.1912
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