VLT® 5000 Crane
■
Extreme Running Conditions
Short circuit
VLT 5000 Crane is protected against short circuits
by means of current measurement in each of the
three motor phases. A short circuit between two
output phases will cause an overcurrent in the
inverter. However, each transistor of the inverter
will be turned off individually when the short circuit
current exceeds the permitted value.
After 5-10
µ
s the control card turns off the
inverter and the frequency converter will display
a fault code, although depending on impedance
and motor frequency.
Earth fault
The inverter cuts out within 100
µ
s in case of an
earth fault on a motor phase, although depending
on impedance and motor frequency.
Switching on the output
Switching on the output between the motor and the
frequency converter is
NOT
permitted.
Motor-generated overvoltage
The voltage in the intermediate circuit is increased when
the motor acts as a generator. This occurs in two 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 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.
The control unit attempts to correct the ramp if possible.
The inverter turns off to protect the transistors
and the intermediate circuit capacitors when a
certain voltage level is reached.
Mains drop-out
During a mains drop-out, VLT 5000 Crane continues
until the intermediate circuit voltage drops below the
minimum stop level, which is typically 15% below VLT
5000 Crane
’
s lowest rated supply voltage.
The time before the inverter stops depends on the mains
voltage before the drop-out and on the motor load.
Static overload
When VLT 5000 is overloaded (the torque limit in
parameter 221/222 has been reached), the controls will
reduce the speed in an attempt to reduce the load.
If the overload is excessive, a current may
occur that makes the frequency converter cut
out after approx. 1.5 sec.
■
Switching on the Input
Switching on the input depends on the mains
voltage in question. The table below states the
waiting time between cut-ins.
Mains voltage
400 V
415 V
460 V
500 V
Waiting time
48 s
65 s
89 s
117s
■
Vibration and Shock
VLT 5000 Crane has been tested according to a
procedure based on the following standards:
IEC 68-2-6:
Vibration (sinusoidal) - 1970
IEC 68-2-34:
Random vibration broad-band
- general requirements
IEC 68-2-35:
Random vibration broad-band
- high reproducibility
IEC 68-2-36:
Random vibration broad-band
- medium reproducibility
VLT 5000 Crane complies with requirements that
correspond to conditions when the unit is mounted
on the walls and floors of production premises, as
well as in panels bolted to walls or floors.
MG.50.N4.02 - VLT is a registered Danfoss trademark
112
