See I/O specs on page 4–6.

4–31

L100 Inverter

TIP: When using the analog meter for monitoring, adjust the meter so it has a zero reading when the [FM] output is zero. Then use scale factor B_81 to adjust the [FM] output so the maximum frequency in the inverter corresponds to a full-scale reading on the meter.

The following accuracy notes apply for PWM monitor outputs:

•The monitor accuracy for frequency monitoring after adjustment is about ±5%. Depending on the motor, the accuracy may exceed this value.

•The monitor display accuracy for current (normally ± 20%, depending on the connected motor’s characteristics) can be improved by adjusting parameter B_32.

•The accuracy of the current reading is given by the equation:

Imc---------------------–Im

⋅ 100 ≤ ± 20%

Im = Inverter output current (measured)

Imc = Monitor display current

Ir

 

Ir = Inverter rated current

 

 

•If precise current measurement is necessary, use the moving-coil type ammeter between the inverter and the motor.

PWM Smoothing Circuit – You may also

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

H

O

OI

 

L

FM

CM2

12

11

 

 

wish to smooth the PWM signal at the [FM]

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

terminal and convert it to an analog signal.

 

 

 

 

–

 

 

 

 

+

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The [FM] terminal will then generate a

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

relatively stable DC analog voltage that

 

 

 

 

 

 

 

 

82kΩ

 

represents the output value. To do this, use

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

+

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

the circuit shown to the right. Note the

 

 

33kΩ

 

 

 

 

 

 

 

 

+

1∝F

Volts

 

 

 

 

 

 

 

 

 

 

output impedance of the circuit is at least

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

–

 

Ω

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

82k , so the monitoring device needs an input impedance of 1MΩ or greater. Other- wise, the impedance of the smoothing

circuit will cause a non-linearity in the reading.

FM Signal Type

The frequency-modulatedoutput at terminal [FM] varies its frequency with the inverter output frequency (C_23=03). The multiplier is 10, such that the maximum [FM] signal frequency is 10 x 360 = 3.6 kHz, or 10 times the inverter’s maximum output frequency. The signal at [FM] uses the parameter A_04 Maximum frequency setting. For example, if A_04 = 60 Hz, then the maximum signal value at [FM] will be 10 x 60 = 600 Hz. This frequency is digitally controlled for accuracy, and does not use the B_81 gain setting when C_23=03 (frequency modulation selection).

[FM]

 

 

 

 

 

 

 

50% fixed duty cycle

1

 

 

 

 

 

 

 

10V

 

 

 

 

 

 

 

 

 

 

 

 

[FM] Output value =

 

 

 

 

 

 

 

 

 

 

 

 

T------⋅----10-----

 

 

 

 

 

 

 

 

 

 

 

 

0V

 

 

 

 

 

 

 

 

 

 

 

 

C_23 = 02

Selects FM type output

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

T

 

 

 

 

 

t

 

 

 

 

 

 

 

 

 

1

 

 

 

 

 

T =

 

 

 

 

 

 

 

 

 

[FM]- Output value ⋅ 10-------------------------------------------------------

Operations Monitoring and