For 200 - 240 V units:
Presistor
= 390
2 ×
dutytime
R
× 120
For 380 - 480 V units:
Presistor
= 778
2 ×
dutytime
R
× 120
For 525 - 600 V units:
Presistor
= 943
2 ×
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 is 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 the 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 con-
nection 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. The brake resistor disconnection function is tested dur-
ing 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.
VLT
®
AQUA Drive Programming Guide
2. Parameter Description
MG.20.O2.02 - VLT
®
is a registered Danfoss trademark
59
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