The Expert's Corner

Let's compare the benefits and issues associated with buying a loose Variable Frequency Drive (VFD) to control a Ross mixer vs. an integrated Ross SysCon Control Panel.

Loose VFD

Ross SysCon Control Panel

Loose VFD No lockout/tagout provisions. OSHA, NEC (670.4-B) and local codes require an energy-isolating device that can be locked out and has a prominent warning tag to protect employees from unexpected start-up or release of energy during service and maintenance. No Emergency Stop button. No primary fusing. If VFD is mounted and wired by Ross, some of the wiring issues go away but lockout/tagout and E-Stop must still be addressed. Can be difficult for the end user to tie in all pieces together. Hiring an outside electrical contractor with limited knowledge of Ross equipment can contribute to start-up delays. Multiple user manuals for wiring instructions. Limited tech support from different manufacturers.

Main power disconnect with lockout/tag out provided. Per OSHA and NFPA-70 (9.2.5.4) requirements, Ross SysCon Control Panels include an Emergency Stop button which when depressed removes all potential dangers from moving parts. Fuse protection for all motors included. Ross technicians mount and wire the Control Panel to the mixer. The system is fully tested and guaranteed to work. End user has only one tie-in point (main power). Mixer manual prepared by Ross engineers includes a full set of electrical drawings and control operating procedures. Comprehensive tech support from Ross. Ross SysCon Control Panels offer great value to end users on a tight budget and schedule. Purchasing the VFD and other peripheral items separately can end up costing more if not properly configured.

Sample Equipment: PowerMix Planetary Disperser

• 3 HP motor for the planetary stirrer
• 7.5 HP motor for the high speed disperser

Loose VFD

Ross SysCon Control Panel

Extensive integration needed. Components sourced from different vendors must all be compatible to operate successfully. Multiple mounting and wiring challenges. Unless the VFD is supplied by Ross, it will need to be programmed to accommodate all safety switches and E-Stop devices as well as provide short circuit and overload protection to the motor. Incorrect sizing or installation of VFD can cause major problems to the motor, noise and safety concerns with the equipment. Nuisance tripping may be experienced when the VFD is not set up to match the application (i.e. proper acceleration/deceleration, torque, power load, etc.). The above complexities increase as the number of agitators in a mixing system increases. Meanwhile, the simplicity of a Ross SysCon Control Panel remains the same: only one input power connection is required.

User-friendly touchscreen interface or standard push buttons and readouts for independent variable speed control of both agitators, mixer close/open, percent load, cycle timer and temperature. Choice of any NEMA enclosure type to meet your specific application and environment. Single point power hook-up. If wall-mounted controls are preferred, a Junction Box is supplied on the mixer. All Ross SysCon Control Panels are built and wired to NFPA-79 and UL-508A standards. Mixer is production-ready immediately upon set-up. Ross technicians are available for troubleshooting support when needed. Factory Acceptance Testing (FAT) offered at all Ross facilities upon request. For sophisticated systems, on-site start-up support can also be arranged. One year standard warranty.

Ross Systems and Controls is a full service machine and controls fabrication facility. We have extensive experience in designing and building control systems not only for Ross Mixers and Blenders but also other types of equipment and processes. All Ross SysCon products are tailored to the customers' exact requirements – from simple start/stop/speed commands to PLC-based recipe driven systems with supervisory control and data acquisition (SCADA) packages.