Installation - WEG CFW-09 User Manual

CHAPTER 8 - CFW-09 OPTIONS AND ACCESSORIES

8.10.2 Installation

270
(1) The maximum current can be determined by:
I = Value set at P153 [V] / Resistor Ohms
max
(2) The RMS braking current can be calculated by
[min]
t
I = I . Where t
br
rms max
5
times during the most severe 5 minute cycle.
(3) P and P are the maximum peak and rated powers that the braking
max rated
chopper can deliver. The resistor power must be sized according to the
application braking duty cycle.
Connect the braking resistor between the +UD and BR power terminals
(refer to item 3.2.1);
Make this connection with a twisted pair. Run this cable separately from
any signal or control wire;
Size the cable cross section according to the application, considering
the maximum and RMS current;
If the braking resistor is installed inside the inverter panel, consider the
heat dissipated by the resistor when defining the panel ventilation;
Set Parameter P154 to the Ohms value of the DB resistor and Parameter
P155 to the resistor power rating in kW.
DANGER!
The CFW-09 provides an electronic thermal protection for the braking resistor
to avoid overheating. The braking resistor and the transistor can be damaged if:
They are not properly sized;
Parameters P153, P154 and P155 are not properly set;
The line voltage exceeds the maximum allowed value.
The electronic thermal protection provided by the inverter, if properly
programmed, protects the DB resistor in case of overloads not expected during
normal operation, but it does not ensure protection in case of a dynamic
braking circuit failure.
In this case the only guaranteed method to avoid burning the resistor and
eliminate risk of fire is the installation of a thermal overload relay in series with
the resistor and/or the installation of a thermostat on the resistor body, wiring
it in a way to disconnect the inverter power supply is case of overheating, as
shown below:
Contactor
Circuit Breaker
Power
Supply
Control Power
Supply
Thermostat
Figure 8.22 – Braking resistor connection
NOTE!
Through the power contacts of the bimetallic overload relay circulates Direct
Current during the DC-Braking process.
corresponds to the sum of the braking
br
CFW-09
or
BR
+UD
Overload
Relay
Braking
Resistor