Disconnect Switch; Fusing; Line Chokes; Motor Thermal Protection - KEB COMBIVERT F5 Instruction Manual

1.4.3 Disconnect switch

A disconnect switch or contactor should be provided as a means of turning off the
supply voltage when the unit is not in use or when it must be serviced.
Repetitive cycling on and off of the input supply voltage more than once every two
minutes can lead to damage of the inverter.

1.4.4 Fusing

A circuit breaker or a disconnect switch with fuses must be provided in
accordance with the National Electric Code (NEC) and all local codes.
The F5 is to be connected to the supply voltage using Class RK5 (BUSSMANN
type FRS-R or equivalent) or using a magnetic trip circuit breaker with Class
D trip characteristic, ratings as specified per unit size in the tables on pages 12-
16.
The minimum voltage rating for protection devices used with 230V inverters shall be
250VAC. The minimum voltage rating for protection devices used with 460V invert-
ers shall be 600VAC.
Fuses should not be installed between the inverter and the motor.

1.4.5 Line Chokes

A line choke with minimum 3% impedance is required for all 230 V inverters
50hp (size 20) and greater. A line choke with minimum 3% impedance is
required for all 460V inverters 100hp (size 23) and greater.
In general a line choke is recommended and can be used prevent nuisance errors
caused by voltage spikes. Additionally, use of a line choke will increase the
operational lifetime of the unit.

1.4.6 Motor Thermal Protection

The F5 series inverters are UL approved as a solid state motor overload protection
device. It is necessary to adjust the current trip level in parameter CP.20. The function
assumes the use of a non-ventilated motor. The function meets the requirements set
forth in VDE 0660 Part 104, UL508C section 42, NEC 430 part C. See the description
for parameter CP.20 for the trip characteristics.
A motor winding sensor can also be used for additional safety and the highest level
of protection. Either a normally closed contact (rating: 15V / 6mA) or a PTC (positive
temperature coefficient) resistor can be connected to the T1, T2 terminals on the
inverter. The thermal device should be connected as indicated on page 19.
General
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