Earth Leakage Current; Extreme Running Conditions - GE AF-600 FP Design Manual

2.11 Earth Leakage Current

Warning:
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Touching the electrical ts may be fatal - even after the equipment has been disconnected from mains.
Also make sure that other voltage inputs have been disconnected, such as load sharing (linkage of DC intermediate circuit), as well as the
motor connection for kinetic back-up.
Before touching any electrical parts, wait at least the amount of time indicated in the Safety Precautions section.
Shorter time is allowed only if indicated on the nameplate for the specific unit.
Leakage Current
The earth leakage current from the frequency converter exceeds 3.5 mA. To ensure that the earth cable has a good mechanical connection
to the earth connection (terminal 95), the cable cross section must be at least 10 mm
Residual Current Device
This product can cause a d.c. 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, another protective measure shall be applied,
such as separation from the environment by double or reinforced insulation, or isolation from the supply system by a transformer.
Protective earthing of the frequency converter and the use of RCD's must always follow national and local regulations.

2.13 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 please see the design guidelines.
Switching on the Output
Switching on the output between the motor and the frequency converter is fully permitted. You cannot damage the frequency converter in any way by switching
on the output. However, fault messages may appear.
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 if the moment of inertia is high, the friction is low and the decel 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.
The control unit may attempt to correct the ramp if possible (par. B-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 par. B-10 Brake Function and par. B-17 Over-voltage Control to select the method used for controlling the intermediate circuit voltage level.
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 frequency converter's lowest rated supply voltage. The mains voltage before the drop-out and the motor load determines how long it takes for the
inverter to coast.
Static Overload in Advanced Vector Control mode
When the frequency converter is overloaded (the torque limit in par. F-40 Torque Limiter (Driving)/par. F-41 Torque Limiter (Braking) is reached), the controls reduces
the output frequency to reduce the load.
If the overload is excessive, a current may occur that makes the frequency converter cut out after approx. 5-10 s.
Operation within the torque limit is limited in time (0-60 s) in par. SP-25 Trip Delay at Torque Limit.
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AF-600 FP Design Guide
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or 2 rated earth wires terminated seately.