That's why R&M, the industry leader in innovation, uses variable frequency drives as standard for trolley and bridge controls and offers as an option the most comprehensive offering of variable frequency drives for hoisting controls.

More Versatility

Flexibility in speed selection and slower speeds offer precise load positioning and reduced load swing.

• Infinitely variable (stepless - EP) or multi-step (defined speeds - MS) speed control
• Wider range of selectable speed range - very slow speeds can be achieved

Better Performance and Prolonged Equipment Lift

Dynamic braking, controlled acceleration and deceleration, and motor over-current and over- temperature protection are some of the VFD features that provide better performance and prolong the equipment life.

• Dynamic braking is a technique of electric braking in which the retarding force is supplied by the inverter. As the operator releases the control device (pushbutton), the output frequency of the inverter decreases to nearly zero which brings the motor to almost a complete stop before the brake is engaged.Controlled acceleration / deceleration provides smooth starts and stops and lowers starting currents, reducing gear and motor wear and structural stress on mechanical components - leading to longer equipment life.
• Motor over-current and over-temperature protection ensures that the motor is operating at its top performance levels.

Variable Frequency Control Versus Two-speed Contactor Control

Infinitely variable (EP) speed control gives the operator the ability to smoothly accelerate, decelerated and hold any speed between the defined minimum and maximum speed.

Two-speed contactor control does not offer the operator the ability to smoothly accelerate or decelerate between the defined speeds

CMXC 007:

• Two-step multi-speed (MS-2) orTwo-step infinitely variable (EP-2)Dynamic brakingMaximum current rating/power rating 2.4 A / 0.75 kW [1 hp]Supply voltage 380 - 480 Vac ±10%*Nominal supply frequency 48 - 62 Hz
• Auto transformer and line reactor are standard

CMXC 022:

• Two-step multi-speed (MS-2) orTwo-step infinitely variable (EP-2)Dynamic brakingCapability to reduce the deceleration time to 30% of acceleration timeSlowdown limit switch capabilityMaximum current rating/power rating 5.1 A / 2.2 kWSupply voltage 380 - 500 Vac ± 10% *
• Nominal supply frequency 48 - 62 Hz

Factory Settings of Inverters

Unless the crane builder and/or user specifies otherwise, the inverters are factory set for two-step infinitely variable (EP-2) and dynamic braking, and the output speed ratio is 4:1 for traveling (trolley or bridge) and 6:1 for hoisting.

Note: Two-step infinitely variable (EP-2) and two-step multi-speed (MS-2) allow the use of a two-step buttons, which is the standard pushbutton supplied by R&M.

* A transformer is used to supply the correct voltage when the power supply is outside of the inverter's range.

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