
5.1.10 Safety Functions in Connection with Installation
When a brake resistor is installed, the best possible endeavours 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 is fitted that cuts out the frequency converter if the brake current is too high. Danfoss' 40% brake
resistors contain a KLIXON switch. Flat pack resistors are self-protecting.
The brake current setting on the thermal relay is calculated as follows:
I
THERMAL
= P
AVG
R
BR
R
BR
is the brake resistor value at any given time.
The drawing shows an installation with a thermal relay.
5.1.11 Internal Brake Resistor
For occasional braking or braking with low duty cycle internally mountable brake resistors are available. (See
Accessories for FCD 300
).
VLT
®
Decentral FCD 300 Design Guide
5 All About FCD 300
MG.90.S1.02 - VLT
®
is a registered Danfoss trademark
123
5