Danfoss FC 300

2-11 Brake Resistor (ohm)
Range: Function:
Size re-
lated
[Ohm] Set the brake resistor value in Ohms. This value is used for
monitoring the power to the brake resistor in par. 2-13
Brake
Power Monitoring
. This parameter is only active in frequency
converters with an integral dynamic brake.
2-12 Brake Power
Range: Function:
kW
*
[0.001 - Size related] Set the monitoring limit of the brake power transmitted to the
resistor.
The monitoring limit is a product of the maximum duty cycle
(120 sec.) and the maximum power of the brake resistor at that
duty cycle. See the formula below.
For 200 - 240 V units:
P
resistor
=
390
2
× dutytime
R
× 120
For 380 - 480 V units
P
resistor
=
778
2
× dutytime
R
× 120
For 380 - 500 V units
P
resistor
=
810
2
× dutytime
R
× 120
For 575 - 600 V units
P
resistor
=
943
2
× dutytime
R
× 120
This parameter is only active in drives with an integral dynamic brake.
2-13 Brake Power Monitoring
Option: Function:
This parameter is only active in frequency converters with an
integral dynamic brake.
This parameter enables monitoring of the power to the brake
resistor. The power is calculated on the basis of the resistance
(par. 2-11
Brake Resistor (Ohm)), the DC link voltage, and the
resistor duty time.
[0]
*
Off No brake power monitoring required.
[1] Warning Activates a warning on the display when the power transmitted
over 120 s exceeds 100% of the monitoring limit (par. 2-12
Brake Power Limit (kW) ).
The warning disappears when the transmitted power falls below
80% of the monitoring limit.
[2] Trip Trips frequency converter and displays an alarm when the cal-
culated power exceeds 100% of the monitoring limit.
[3] Warning and Trip Activates both of the above, including warning, trip and alarm.
If power monitoring is set to
Off [0] or Warning [1], the brake function remains active, even if the
monitoring limit is exceeded. This may lead to thermal overload of the resistor. It is also possible
to generate a warning via a relay/digital outputs. The measuring accuracy of the power monitoring
depends on the accuracy of the resistance of the resistor (better than ± 20%).
FC 300 Programming Guide 2. How to Programme
MG.33.M2.02 - VLT
®
is a registered Danfoss trademark 65
2