Function Setting
7-00 Speed PID
Feedback Source
[2] MCB 102
17-11 Resolution
(PPR)
1024*
13-00 SL
Controller Mode
[1] On
13-01 Start
Event
[19] Warning
13-02 Stop
Event
[44] Reset
key
13-10 Comparat
or Operand
[21] Warning
no.
13-11 Comparat
or Operator
[1] ≈*
13-12 Comparat
or Value
90
13-51 SL
Controller Event
[22]
Comparator 0
13-52 SL
Controller Action
[32] Set
digital out A
low
5-40 Function
Relay
[80] SL digital
output A
* = Default Value
Notes/comments:
Warning 90 will be issued when
the feedback signal from the
encoder does not correspond
to the reference. The SLC
monitors Warning 90 and in
the case that Warning 90
becomes TRUE then Relay 1 is
triggered.
External equipment may then
indicate that service may be
required.
Table 3.19 Using SLC to Set a Relay
3.11
Extreme Running Conditions
Short Circuit (Motor Phase – Phase)
The frequency converter is protected against short circuits
by means of current measurement in each of the three
motor phases or in the DC link. A short circuit between
two output phases will cause an overcurrent in the
inverter. The inverter will be turned off individually when
the short circuit current exceeds the permitted value
(Alarm 16 Trip Lock).
To protect the frequency converter against a short circuit
at the load sharing and brake outputs see the design
guidelines.
Switching on the Output
Switching on the output between the motor and the
frequency converter is permitted. Fault messages may
appear. Enable flying start to catch a spinning motor.
Motor-generated Over-voltage
The voltage in the intermediate circuit is increased when
the motor acts as a generator. This occurs in following
cases:
1. The load drives the motor (at constant output
frequency from the frequency converter), ie. the
load generates energy.
2. During deceleration ("ramp-down") if the moment
of inertia is high, the friction is low and the ramp-
down time is too short for the energy to be
dissipated as a loss in the frequency converter,
the motor and the installation.
3. Incorrect slip compensation setting may cause
higher DC link voltage.
4. Back-EMF from PM motor operation. If coasted at
high rpm the PM motor back-EMF may
potentially exceed the maximum voltage
tolerance of the frequency converter and cause
damage. To help prevent this, the value of
4-19 Max Output Frequency is automatically
limited based on an internal calculation based on
the value of 1-40 Back EMF at 1000 RPM,
1-25 Motor Nominal Speed and 1-39 Motor Poles.
If it is possible that the motor may overspeed
(e.g. due to excessive windmilling effects) then it
is recommended to equip a brake resistor.
WARNING
The frequency converter must be equipped with a break
chopper.
The control unit may attempt to correct the ramp if
possible (2-17 Over-voltage Control).
The inverter turns off to protect the transistors and the
intermediate circuit capacitors when a certain voltage level
is reached.
See 2-10 Brake Function and 2-17 Over-voltage Control to
select the method used for controlling the intermediate
circuit voltage level.
NOTE
OVC can not be activated when running a PM motor
(when1-10 Motor Construction is set to [1] PM non salient
SPM).
Mains Drop-out
During a mains drop-out, the frequency converter keeps
running until the intermediate circuit voltage drops below
the minimum stop level, which is typically 15% below the
Introduction
VLT
®
AutomationDrive FC 300 Design Guide, 0.25-75 kW
MG33BE02 - VLT
®
is a registered Danfoss trademark 51
3
3
http://www.RSPSupply.com/p-21462-Danfoss-131B8966-VLT-Automation-VT-Drive-VFD-FC301-230V-5-HP.aspx
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