F316: Carrier Frequency Control Setting As A Measure To Protect Motorsagainst Surge Voltages; Reduction Of Load Current - Toshiba TOSVERT VF-AS3 Instruction Manual

This function works in the low output frequency range producing unpleasant magnetic noise from
the motor.
<F312: Random switching> has three different tones: "1", "2" and "3". Select the appropriate setting
for the load.
With <F300: Carrier frequency> set to 8.0 kHz or more, the motor magnetic noise decreases, and
thus the random switching does not function.
■ <F316: Carrier frequency control> setting as a measure to protect motors
against surge voltages
When a 480 V class inverter is used to operate a motor, very high surge voltages may be produced
depending on the wire length, wire routing and types of wires used.
Here are some examples of measures against surge voltages.
• Decrease <F300: Carrier frequency>.
• When the wire length between the inverter and motor is long (approx. 20 to 100 m), set <F316:
Carrier frequency control> to "2" or "3".
• Turn off power to set <F316: Carrier frequency control> to "2" or "3".
• Install a sinusoidal filter to the output side of inverter. In this case, set <F316: Carrier frequency
control> to "4" or "5".
• Use a motor with high insulation strength.
• If an overload occurs while <F316: Carrier frequency control> is set to "0: No decrease", an
overload trip will be caused.
• When no decrease of carrier frequency is selected while a high carrier frequency is set, a trip
occurs by overcurrent, etc. more easily than the case with automatic decrease.
• With <F316: Carrier frequency control> set to "2" or "3", the carrier frequency is restricted to 4
kHz or less automatically.
Important
• With <F316: Carrier frequency control> set to "4" or "5", the carrier frequency is 4 kHz or more
automatically.
• With <Pt: V/f pattern> set to "2" - "6" or "9" - "12", the carrier frequency is 2 kHz or more
automatically.

■ Reduction of load current

When the ambient temperature is above 40 or 50°C, reduce the current according to "Instruction
manual for load reduction".
With <F316: Carrier frequency control> set to "0", "2" or "4" (no decrease), an motor overload pre-
alarm "L" or overheat pre-alarm "H" is displayed when the IGBT overload "OL3" or overheat "OH"
protection level nears. When the cumulative amount of overload further increases, an "OL3" or "OH"
trip will occur. In this case, decrease <F601: Stall prevention level 1> to avoid trips.
Even when <F300: Carrier frequency> is set to a low value, the carrier frequency increases in the
high output frequency range to ensure stable operation.
• How to operate the operation panel -> Refer to [3. 1. 1].
Reference
• How to switch display mode on the operation panel -> Refer to [3. 1. 2].
• Procedure to change parameter setting -> Refer to [4. 2. 3]
6-53
E6582062
6. [Advanced] How to use parameters
3
4
6
9