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•
•
•
-
e3
0b
b9
57
.1
2
Leakage current [mA]
100 Hz
2 kHz
100 kHz
Illustration 30: Influence of Cut-off Frequency of the RCD on what is Responded to/Measured
For more details, refer to the RCD Application Note.
W A R N I N G
RESIDUAL CURRENT DEVICE PROTECTION
This product can cause a DC current in the protective conductor. Where a residual current device (RCD) is used for protection in
case of direct or indirect contact, only an RCD of Type B is allowed on the supply side of this product. Otherwise, apply another
protective measure, such as separation from the environment by double or reinforced insulation, or isolation from the supply
system by a transformer. See also application note Protection against Electrical Hazards.
Protective grounding of the drive and the use of RCDs must always follow national and local regulations.
3.7 Extreme Running Conditions
3.7.1 Introduction
Short circuit (motor phase-phase)
Current measurement in each of the 3 motor phases or in the DC-link, protects the drive against short circuits. A short circuit be-
tween 2 output phases causes an overcurrent in the inverter. The inverter is turned off individually when the short circuit current
exceeds the allowed value (
alarm 16, Trip Lock
).
For information about protecting the drive against a short circuit at the load sharing and brake outputs, see
chapter Fuses and Circuit
Breakers
.
Switching on the output
Switching on the output between the motor and the drive is allowed. The drive is not damaged in any way by switching on the
output. However, fault messages may appear.
Motor-generated overvoltage
The voltage in the DC link is increased when the motor acts as a generator. This occurs in following cases:
The load drives the motor (at constant output frequency from the drive), that is the load generates energy.
During deceleration (ramp-down) if the inertia moment is high, the friction is low, and the rampdown time is too short for the
energy to be dissipated as a loss in the drive, the motor, and the installation.
Incorrect slip compensation setting (
parameter 1-62 Slip Compensation
) may cause higher DC-link voltage.
The control unit may attempt to correct the ramp if
parameter 2-17 Over-voltage Control
is enabled. The drive turns off to protect the
transistors and the DC-link capacitors when a certain voltage level is reached.
AJ363928382091en-000101 / 130R0983 | 41
Danfoss A/S © 2021.04
Product Overview
VLT® Flow Drive FC 111
Design Guide