Brake cable
Max. length [m]: 20 m
The connection cable to the brake resistor must be screened/armoured. Connect the screen to the conductive
backplate at the frequency converter and to the brake resistor metal cabinet by means of cable clamps.
NB!
If Danfoss brake resistors are not used, it must be ensured that the brake resistor is induction-free.
Protective functions during installation
When a brake resistor is installed, the best possible
endeavors should be made to avoid overloads, as the
heat generating from a brake resistor may involve a
fire risk.
NB!
The brake resistor should be fitted to a
nonflammable material.
For protection of the installation, a thermal relay should
be fitted that cuts off the frequency converter if the
brake current becomes too high. Flat pack resistors
are self-protecting.
Calculate the brake current setting of the thermal relay
as follows:
Itherm relay
=
P
avg
R
brakeresistor
R
br
is the current brake resistor value calculated in the
section on “Calculation of brake resistance”. The figure
shows an installation with a thermal relay.
The brake current setting of thermal relay for Danfoss
40% brakeresistors can be found in the table further
on.
Some of the Danfoss Brakeresistors contain a thermal
switch (see table further on). This switch is NC (nor-
mally closed) and can be used e.g. coasting stop
reverse between terminal 12 and 27. The drive will
then coast, if the thermal switch is opened.
NB!
The thermal switch is not a protective de-
vice. For protection, use a thermal switch
as shown in the figure.
26
MG.27.E2.02 - VLT is a registered Danfoss trademark