Danfoss VLT AutomationDrive FC 300 Operating Instructions Manual page 75

How to Programme the Low Ha...
2-13 Brake Power Monitoring
Option:
[0] Off
*
[1] Warning
6 6
[2] Trip
[3] Warning
and trip
If power monitoring is set to [0] Off or [1] Warning, 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:
74
VLT Automation Low Harmonic Drive Operating Instructions
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
(2-11 Brake Resistor (ohm)), the DC link voltage,
and the resistor duty time.
No brake power monitoring required.
Activates a warning on the display when the
power transmitted over 120 s exceeds 100% of
the monitoring limit (2-12 Brake Power Limit
(kW) ).
The warning disappears when the transmitted
power falls below 80% of the monitoring limit.
Trips frequency converter and displays an
alarm when the calculated power exceeds
100% of the monitoring limit.
Activates both of the above, including
warning, trip and alarm.
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.
NOTE
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 Æms without braking.
2. The DC link ripple amplitude is
measured for 300 Æms with the brake
turned on.
3. If the DC link ripple amplitude while
braking is lower than the DC link ripple
MG34O202 - VLT
2-15 Brake Check
Option: Function:
4.
[0] Off Monitors brake resistor and brake IGBT for a
short-circuit during operation. If a short-circuit
*
occurs, warning 25 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 Monitors for a short-circuit or disconnection of
trip 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 (e.g. warning 25, 27 or 28).
[4] AC brake 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
performs a controlled ramp-down. This option is
available for FC 302 only.
NOTE
Remove a warning arising in connection with [0] Off or [1]
Warning by cycling the mains supply. The fault must be
corrected first. For [0] Off or [1] Warning , the frequency
converter keeps running even if a fault is located.
This parameter is only active in frequency converters with
an integral dynamic brake.
6.1.4 2-2* Mechanical Brake
Parameters for controlling operation of an electro-
magnetic (mechanical) brake, typically required in hoisting
applications.
To control a mechanical brake, a relay output (relay 01 or
relay 02) or a programmed digital output (terminal 27 or
29) is required. Normally this output must be closed during
periods when the frequency converter is unable to 'hold'
the motor, e.g. due to an excessive load. Select [32]
Mechanical Brake Control for applications with an electro-
magnetic brake in 5-40 Function Relay, 5-30 Terminal 27
Digital Output, or 5-31 Terminal 29 Digital Output. When
selecting [32] Mechanical brake control, the mechanical
®
is a registered Danfoss trademark
amplitude before braking + 1 %: Brake
check has failed by returning a warning
or alarm.
If the DC link ripple amplitude while
braking is higher than the DC link ripple
amplitude before braking + 1 %: Brake
check is OK.