Mitsubishi Electric FR-F800, Инструкция по эксплуатации

Страница: 249 / 834

Parameters (E) Environment setting parameters
FR-F800 5 - 87
PWM carrier frequency automatic reduction function (Pr. 260)
●
Setting Pr. 260 = "1 (initial value)" will enable the PWM carrier frequency auto-reduction function.
If a heavy load is continuously applied while the inverter carrier frequency is set to 3 kHz or higher
(Pr. 72
≥
"3"), the carrier frequency is automatically reduced to prevent occurrence of the inverter
overload trip (electronic thermal O/L relay function) (E.THT). The carrier frequency is reduced to
as low as 2 kHz. (Motor noise increases, but not to the point of failure.)
●
When the PWM carrier frequency automatic reduction function is used, the operation with the
carrier frequency set to 3 kHz or higher (Pr. 72
≥
"3") automatically reduces the carrier frequency
for heavy-load operation as shown below.
.
Pr. 260 setting Pr. 570 setting Carrier frequency automatic reduction operation
1 0 (SLD), 1 (LD)
Continuous operation with the 85% or higher rated inverter current
reduces the carrier frequency automatically.
0
0 (SLD)
Continuous operation with the 85% or higher rated inverter current
reduces the carrier frequency automatically.
1 (LD)
Without carrier frequency automatic reduction
(Perform continuous operation with the carrier frequency set to 2 kHz or
lower or with less than 85% of the rated inverter current.)
Tab. 5-42: Parameter settings for PWM carrier frequency automatic reduction operation
NOTES Reducing the PWM carrier frequency is effective as a countermeasure against EMI from the
inverter or for reducing leakage current, but doing so increases the motor noise.
When the PWM carrier frequency is set to 1 kHz or lower (Pr. 72
≤
1), the increase in the harmonic
current causes the fast-response current limit to activate before the stall prevention operation,
which may result in torque shortage. In this case, disable the fast-response current limit in Pr. 156
"Stall prevention operation selection".
Parameters referred to
Pr. 156 Stall prevention operation selection => page 5-175
Pr. 570 Multiple rating setting => page 5-68
Pr. 800 Control method selection => page 5-38