Application to Motor

Application to standard motor

When the Mitsubishi standard squirrel-cage motor (SF- JR, 4-pole) and inverter of the same capacity are used, the torque characteristics are as shown below.

Output characteristics

60Hz torque reference

resonance points to be avoided during operation. (During acceleration/deceleration, the frequency within the setting range is passed through.) An effect is also produced if the PWM carrier frequency in Pr. 72 is changed. When a two-pole motor is operated at higher than 60Hz, caution should be taken since such operation may cause abnormal vibration.

Inverter-driven 400V class motor

Continuous output torque (%)

	torque (%)
100	maximum
90
80	Short time
	Short time
50
45
30

*5 *4 *3 *2

120

110

100

Short time maximum torque*1

220V

200V

Continuous operation torque (*6 to 8)

60120 Output frequency (Hz)

When driving a 400V class motor by the inverter, surge voltages attributable to the wiring constants may occur at the motor terminals, deteriorating the insulation of the motor. In such a case, consider taking the following measures.

(1) Rectifying the motor insulation

1. Use a "400V class inverter driven insulation-

enhanced motor".

Note: The four poles of the Mitsubishi standard

50Hz torque reference

torqueoutputContinuous(%)		torquemaximumtimeShort(%)	5 4 *3	*2	Short time maximum torque*1
torqueoutputContinuous(%)		torquemaximumtimeShort(%)	104
			95
	85
			80
	75
	65		67
	65
			53
	45				Continuous operation torque
	38				Continuous operation torque
	38				(*6 to 8)
					(*6 to 8)

2525

0	1	3	6	20	30	50	120	Output
								frequency (Hz)

*1 The 60Hz torque reference indicates that the rated torque of the motor running at 60Hz is 100%, and the 50Hz torque reference indicates that the rated torque of the motor running at 50Hz is 100%

*2 Torque boost minimum (0%)

*3 Torque boost standard (initial value)

*4 Torque boost large (0.75K... 10%, 1.5K to 3.7K... 7%, 5.5K, 7.5K... 6%, 11K or more... 4%) *5 Enabled for torque boost adjustment (3.7kW or less) or simple magnetic flux vector

control (slip compensation setting)

*6 A general-purpose, squirrel-cage motor must be used at lower continuous operating torque in rated operation as shown in the chart since the cooling capability of the fan installed on the rotor reduces at a lower speed. (Instantaneous torque occurs)

*7 200/220V 60Hz or 200V 50Hz in the chart indicates a motor torque standard (base frequency set in Pr. 3 of the inverter) and is not the frequency of the power supply. You can also set 60Hz in a 50Hz power supply area.

*8 As shown in the chart, the 60Hz torque reference setting allows you to use the motor more efficiently as it can bring out the 100% torque of the motor continuously.

*9 This chart shows the characteristic available when a constant-torque load is selected for load pattern selection (Pr. 14).

Motor loss and temperature rise

The motor operated by the inverter has a limit on the continuous operating torque since it is slightly higher in temperature rise than the one operated by a commercial power supply. At a low speed, reduce the output torque of the motor since the cooling effect decreases. When 100% torque is needed continuously at low speed, consider using a constant-torque motor.

Torque characteristic

The motor operated by the inverter may be less in motor torque (especially starting torque) than the one driven by the commercial power supply. It is necessary to fully check the load torque characteristic of the machine.

Vibration

The machine-installed motor operated by the inverter may be slightly greater in vibration than the one driven by the commercial power supply. The possible causes of vibration are as follows.

1.Vibration due to imbalance of the rotator itself including the machine

2.Resonance due to the natural oscillation of the mechanical system. Caution is required especially when the machine used at constant speed is operated at variable speed. The frequency jump function allows

motor (SF-JR, SB-JR) have the 400V class

inverter driving insulation-enhanced feature.

2. For the dedicated motor such as the constant-torque

motor and low-vibration motor, use the "inverter-

driven, dedicated motor".

(2) Suppressing the surge voltage on the inverter side

Connect a filter on the secondary side of the inverter to

suppress a surge voltage so that the terminal voltage of the

motor is 850V or less. When driving by the Mitsubishi

inverter, connect an optional surge voltage suppression filter

(FR-ASF-H) for the 55K or less and an optional sine wave

filter (MT-BSL, BSC) for the 75K or more on the inverter

output side.

Application to constant-torque motor

Since a constant-torque motor is greater in current than the standard motor, the inverter capacity may be one rank higher. For a constant-torque motor, decrease the torque boost setting. Recommended value 0.75kW... 6%, 1.5 to 3.7kW... 4%,

5.5to 7.5kW...3%, 11 to 37kW...2%,

45 to 55kW...1.5%, 75k or more...1%

When two or more motors are operated synchronously, torque imbalance is likely to occur as motor slip is smaller than that of the standard motor.

Application to special motors

Pole changing motor

As this motor differs in rated current from the standard motor, confirm the maximum current of the motor and select the inverter. Be sure to change the number of poles after the motor has stopped. If the number of poles is changed during rotation, the regenerative overvoltage protecion circuit may be activated to cause an inverter alarm, coasting the motor to a stop.

Geared motor

The continuous operating rotation range of this motor changes depending on the lubrication system and maker. Especially in the case of oil lubrication, continuous operation in the low speed range only can cause gear seizure. For fast operation at higher than 60Hz, please consult the maker.

Synchronous motor

This motor is not suitable for applications of large load variation or impact, where out-of-sync is likely to occur. Please contact us when using this motor because its starting current and rated current are greater than those of the standard motor and will not rotate stably at low speed.