YASKAWA V1000 Series Technical Manual page 277

UL recognized electronic thermal overload function of the drive: Speed-dependent heat characteristics are simulated using data from standard motors
and force-ventilated motors. The motor is protected from overload using this function.
Using One Drive with Multiple Motors
Turn off the electronic thermal overload function. Please refer to the appropriate product instruction manual to determine which parameter disables this
function.
The UL recognized electronic thermal overload function of the drive cannot be applied when using multiple motors on one drive. The electronic thermal
function is calculated using the output current of the drive. Individual motor currents cannot be determined using the output current of the drive. Therefore,
a thermal relay is required for each motor connected to the drive.
Wiring Length Greater Than 50 meters (164 feet)
When motor wiring is longer than 164 feet (50 meters), nuisance tripping of the thermal relay may occur if a high carrier frequency is used. Due to
increased high frequency leakage current the thermal relay element may overheat due to surface skin effect. Therefore, reduce the carrier frequency.
The following should be considered for long motor cable length applications:
1. For a single motor drive, use the electronic thermal overload function of the drive (thermal relay not required).
2. For multiple motor drives:
Lower the carrier frequency according to
Voltage Boost and High Torque V/f Pattern Settings
The V/f pattern and voltage boost settings may impact motor heating. Improperly adjusted V/f patterns or torque compensation settings may cause over-
excitation of the motor, resulting in additional motor heating. Unintentional triggering of the overload device may also occur. Therefore, do not use high
starting torque V/f patterns or use excessive voltage boost settings unless absolutely necessary.
Correcting Nuisance Tripping Resulting from High AC Drive Carrier Frequency
Thermal overload element heating is influenced by carrier frequency and lead length. Current waveforms generated by PWM drives tend to create additional
temperature rise in overload relays. Therefore, it may be necessary to increase the trip level setting by the factors listed in
nuisance triggering of the relay. Confirm an actual overload condition is not present prior to increasing the trigger level.
WARNING! Risk of Fire. Confirm an actual motor overload condition is not present prior to increasing the thermal OL trip setting. Check local electrical codes before making
adjustments to motor thermal overload settings.
Example: A thermal OL relay with an adjustment range of 1.1 to 1.6 A is used with a drive working with 8 kHz carrier frequency. The motor rated current
is 1.2 A. The overload trip level may be corrected to: 1.2 A x 1.21 = 1.45 A
Table 8.3 shows recommended correction factors for the motor protection device trigger level based on adjustment range and carrier frequency of the
drive.
Adjustment Range / Rated Current
3.2 to 50 A
0.5 to 2.5 A
0.32 to 0.4 A
0.16 to 0.25 A
System Component Compatibility
Thoroughly review the application requirements to ensure compatibility of the selected components (motor, speed range, application speed-torque
requirements).
YASKAWA ELECTRIC SIEP C710606 18A YASKAWA AC Drive – V1000 Technical Manual (Preliminary)
Figure 8.15 or correct the motor thermal OL relay adjustment according to
Figure 8.15 Criteria for Setting Carrier Frequency
Table 8.3 Motor Protection Device Correction Factors
2 4 6
1.07 1.12 1.16
1.08 1.13 1.17
1.09 1.15 1.21
1.10 1.17 1.24
Drive Carrier Frequency Setting (KHz)
8 10
1.18 1.19
1.21 1.24
1.25 1.29
1.28 1.33
8.4 Installing Peripheral Devices
Table 8.3 .
Table 8.3
when encountering
12 14 16
1.21 1.22 1.23
1.26 1.28 1.29
1.33 1.35 1.37
1.38 1.42 1.46
8
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