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For 200 - 240 V units:
Presistor =
3902 ×
dutytime
R × 120
For 380 - 480 V units
Presistor =
7782 ×
dutytime
R × 120
For 380 - 500 V units
Presistor =
8102 ×
dutytime
R × 120
For 575 - 600 V units
Presistor =
9432 ×
dutytime
R × 120
This parameter is only active in frequency converters 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 calculated 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%).
2-15 Brake Check
Option:
Function:
Select type of test and monitoring function to check the connection to the brake resistor, or whether a brake
resistor is present, and then display a warning or an alarm in the event of a fault.
NB!
The brake resistor disconnection function is tested during power-up. However the brake IGBT
test is performed when there is no braking. A warning or trip disconnects the brake function.
The testing sequence is as follows:
1.
The DC link ripple amplitude is measured for 300 ms without braking.
2.
The DC link ripple amplitude is measured for 300 ms with the brake turned on.
3.
If the DC link ripple amplitude while braking is lower than the DC link ripple amplitude before braking
+ 1 %:
Brake check failed, return a warning or alarm.
4.
If the DC link ripple amplitude while braking is higher than the DC link ripple amplitude before braking
+ 1 %:
Brake check OK.
[0]
*
Off
Monitors brake resistor and brake IGBT for a short-circuit during operation. If a short-circuit occurs, a warning
appears.
[1]
Warning
Monitors brake resistor and brake IGBT for a short-circuit, and runs a test for brake resistor disconnection during
power-up.
[2]
Trip
Monitors for a short-circuit or disconnection of the brake resistor, or a short-circuit of the brake IGBT. If a fault
occurs, the frequency converter cuts out while displaying an alarm (trip locked).
[3]
Stop and Trip
Monitors for a short-circuit or disconnection of the brake resistor, or a short-circuit of the brake IGBT. If a fault
occurs, the frequency converter ramps down to coast and then trips. A trip lock alarm is displayed.
FC 300 Programming Guide
2. How to Programme
MG.33.M3.02 - VLT
®
is a registered Danfoss trademark
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