When you have a problem with your industrial drive system leading to unplanned downtime, the clock is ticking. Every maintenance technician and electrician knows the frustration of working with an electrical control enclosure often larger than the machines it controls. The problem could be with the drive, the motor, the cabling or some other source.
Bosch Rexroth’s cabinet-free technology separates the components of your motion control system into discrete IP65 enclosures so that the layout of your system is clear and easy to use. We spoke with Karl Rapp, industry manager at Bosch Rexroth, about the system.
“In traditional drive technology, you may see, for example, a range of servo drives,” said Rapp. “You normally have to mount the frequency converter drives into an enclosure with cables running to the motors. You also must cool all the heat dissipation of these devices out of the cabinet. In packaging, automation and machine tools, we are transitioning all of our markets into the cabinet-free technology.”
The contactor and line filter are mounted into an IP65 housing. The power supply is in an IP65 housing. The system does all the switching between high power and power supply internally. It creates clean DC voltage, coming through a single cable and going to multiple motors.
“This reduces the cabling from the cabinet to the individual motor, but initially, none of these components are inside of an electric enclosure, so you don’t need any electric enclosure, and you don’t need to cool that enclosure,” said Rapp. “A lot of machines today have the problem that the enclosure has more footprint than the machine! This technology allows the machine builder to mount the drives on the top of the machine or on the side, in the same footprint, and not in a separate enclosure.”
Benefits of Cabinet-Free Drives
Simple Cabling
As shown in the video, one cable connects all the motors in a daisy chain.
Troubleshooting
“There’s no need to troubleshoot the cabling between the drive and the motor,” said Rapp. “The DC goes to the motors, and everything else is inside. If there is a problem (or perceived problem), you just change the motor out and download all the parameters and you’re back up and running. So, the troubleshooting time on a machine is drastically reduced.”
Reduced Electrical Noise
With this system, you will see no pulse-width modulation (PWM) noise between the drive and the motor and all the shielding requirements, because it’s all inside the motor and no longer between the cabinet and machine frame.
Flexibility
You can use one power supply to go to up to 20 devices and up to a 100m (328ft) distance, so it’s very good for even conveyor systems or sorting systems or any type of machinery where you have multiple devices able to be strung up on one cable.
If you need to connect traditional motors, we make these drives as a “near motor installation.” You can take this IP65 drive and mount it to a heatsink or mount it to a large steel or aluminum plate, or liquid cool them. You can hook up single or dual cable motors.
Energy Saving
“From a power standpoint, you share the peak power for supplying to the motor and returning from the motor when you are stopping,” said Rapp. “Each device has a capacitor inside, so we increase the complete bus capacity for peak power. We also eliminate the need for bleeder resistors, which cause additional excess heat that must be cooled. This unit is completely line-regenerating, so if we have a lot of energy coming back, it returns the energy into the incoming line automatically.”
For more on troubleshooting, check out “How IIoT Analytics Can Locate and Help Eliminate Causes of Downtime in Your Plant.” This article is about a sensor-based Industrial Internet of Things system that doesn’t just blink a red light to indicate a problem—it shows the exact sensor causing the fault and its location in your plant.