7-5
Chap. 7 MAINTENANCE AND INSPECTION
[ 2 ] Measuring the capacitance of the DC link bus capacitor under ordinary operating conditions
When bit 3 of H98 data is 1, the inverter automatically measures the capacitance of the DC link bus capacitor under ordinary
operating conditions when the power is turned OFF. This measurement requires setting up the load conditions for ordinary
operation and measuring the reference capacitance when the inverter is introduced to the practical operation, using the setup
procedure given below.
------------------------------------------------ Reference capacitance setup procedure ----------------------------------------------------
1) Set function code H98 (Protection/maintenance function) to enable the user to specify the judgment criteria for the service
life of the DC link bus capacitor (Bit 3 = 1) (refer to function code H98).
2) Turn OFF all run commands.
3) Make the inverter ready to be turned OFF under ordinary operating conditions.
4) Set both function codes H42 (Capacitance of DC link bus capacitor) and H47 (Initial capacitance of DC link bus capacitor)
to "0000."
5) Turn OFF the inverter, and the following operations are automatically performed.
The inverter measures the discharging time of the DC link bus capacitor and saves the result in function code H47 (Initial
capacitance of DC link bus capacitor).
The conditions under which the measurement has been conducted will be automatically collected and saved.
During the measurement, " . . . . " will appear on the LED monitor.
6) Turn ON the inverter again.
Confirm that H42 (Capacitance of DC link bus capacitor) and H47 (Initial capacitance of DC link bus capacitor) hold right
values. Shift to Menu #5 "Maintenance Information" and confirm that the relative capacitance (ratio to full capacitance) is
100%.
If the measurement has failed, "0001" is entered into both H42 and H47. Remove the factor of the failure an
conduct the measurement again.
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Hereafter, each time the inverter is turned OFF, it automatically measures the discharging time of the DC link bus capacitor if
the above conditions are met. Periodically check the relative capacitance of the DC link bus capacitor (%) with Menu #5
"Maintenance Information" in Programming mode.
The condition given above produces a rather large measurement error. If this mode gives you a lifetime alarm, set H98
(Maintenance operation) back to the default setting (Bit 3 (Select life judgment threshold of DC link bus capacitor) =
0) and conduct the measurement under the condition at the time of factory shipment.
[ 3 ] Early warning of lifetime alarm
For the components listed in Table 7.3, the inverter can issue an early warning of lifetime alarm LIFE at one of the transistor
output terminals ([Y1] to [Y4]) and the relay contact terminals ([Y5A] - [Y5C], and [30A/B/C]) as soon as any of the levels
specified in Table 7.3 has been exceeded.
The early warning signal is also turned ON when a lock condition on the internal air circulation DC fan (provided on 200 V
class series inverters with a capacity of 45 kW or above; on 400 V class series inverters with a capacity of 75 kW or above) has
been detected.
7.4 Measurement of Electrical Amounts in Main Circuit
Because the voltage and current of the power supply (input, primary circuit) of the main circuit of the inverter and those of the
motor (output, secondary circuit) contain harmonic components, the readings may vary with the type of the meter. Use meters
indicated in Table 7.4 when measuring with meters for commercial frequencies.
The power factor cannot be measured by a commercially available power-factor meter that measures the phase difference
between the voltage and current. To obtain the power factor, measure the power, voltage and current on each of the input and
output sides and use the following formula.
Three-phase input
%100×
(A)Current×(V)Voltage×3
(W)powerElectric
=factorPower
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