Lenze E82xVxxxKxxxxx - Manual (Page 474)

DC−bus operation
Fuses and cable cross−sections
Protection in DC−bus operation
12
l
474 EDS82EV903−3.0
12.5.3 Protection in DC−bus operation
Fusing concept and risk of damage
For a DC−bus system, we recommend to select a progressive fusing concept. The risk of
damage in the event of an error depends on the selected fusing. The table below helps you
analysing the risk.
)
Note!
ƒ At the motor end, the current limitation of the controller acts as cable
protection. (Check UL appendixes for approval!) Here, the cable cross−section
on the motor side must be dimensioned for the fusing on the supply side.
ƒ For group drives, we recommend to additionally fuse single drives and to
thermally monitor the motors.
ƒ If the mains supply reduces the cable cross−sections towards the individual
axes, the cables must be protected through the following measures:
– Use fuses that ensure cable protection
– Short−circuit−proof laying
– Thermal monitoring of the cables
Definition "Internal error"
For controllers:
ƒ The fault location is between the connection point on the DC busbar and upstream
to terminals U, V, W in the controller.
For power supply units:
ƒ The fault location is between the mains input (terminals L1, L2, L3) and the most
remote location on the DC busbar.
With mains fuses without monitoring function (F1 ... F3)
Cable protection No device protection
Protective
function l On the supply side
l On the DC busbar
l On the motor side
Possible errors One or more controllers with
l device−internal short circuit (+U
G
Õ −U
G
)
l device−internal earth fault (+U
G
ÕPE/−U
G
ÕPE)
Mains supply failure of one
controller with decentralised
supply
Risk Multiple controllers connected in parallel supply the fault
location(s) via the DC busbar. This may lead to the intact
controllers being overloaded because the faulty controller
cannot be activated individually.
Possible damages with central and decentralised supply
l The faulty controller is destroyed
l Still intact controllers are destroyed
l The power supply unit is destroyed
In the event of a failure of a
supply point on the supply side
due to the response of F1...F3,
the still supplied controllers in
the DC−bus system may be
overloaded.