Fagor DDS, Hardware Manual

Page: 229 / 386

   Selection criteria
S
E
LECT
ING CRI
T
ERIA
Ballast
resistor selection
guide
5.
229
DDS
HARDWARE
Ref.1310
5.6 Ballast resistor selection guide
Calculate the value of:
Based on the following formulae:
where:
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.
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 maxi-
mum value among all the (Wmi / ti) quotients of each braking in kW.
Wm Wp
1
2
--- + Jt
2

n 
60
--------------
2
 Ws
 
=
Wp m g

h   =
Pe
Wmi
2
ti
------------
i

T
--------------------- w
 
=
Pmx
Wmi
ti
------------
 
 
 
max
kW
 
=