ARE THESE YOUR GROUNDING ISSUES?

HFES® focuses on addressing issues within the Drive/Motor cabling system that affect Safety, Motors and Sensitive Electronic Devices. Let’s look at each category of issues in more detail.

SAFETY – High frequency ground currents cause potential arcing and sparking at points of physical earth. Safety is a primary concern in the mining industry and other hazardous processing environments where these issues are unacceptable with regard to personnel. Depending on the environment, arcing and sparking at ground can cause severe damage to equipment. High frequency ground currents can also severely affect livestock animals in the vicinity of operating ASD’s. HFES redirects fault currents away from hazardous locations.

PREMATURE MOTOR FAILURE – High frequency ground currents generate motor bearing currents, which cause motor bearing fluting or pitting. The bearing damage causes premature motor failure. No motor manufacturer warranties motor bearings against failures. In addition, when motor speed and frequency are fixed for long periods of time, such as in Clean Room or HVAC applications, the potential is increased for motor bearing currents to discharge through the bearings. By redirecting high frequency ground currents away from the motor bearings, HFES™ reduces motor bearing currents and extends motor life.

SENSITIVE ELECTRONIC DEVICES – High frequency ground currents entering the grounding grid can travel throughout the grid and re-enter open ground paths. EMI and RFI can originate within the drive/motor system, or be radiated by sources nearby. Sensitive devices subjected to these various types of interference can be disrupted, with effects ranging from inaccurate performance to intermittent operation to failure. Manufacturing scrap, unplanned downtime, equipment damage, and building systems or communication/security systems disruption are examples of costly consequences of sensitive electronic device malfunction. HFES™ will permanently address these issues by controlling the high frequency ground currents and electrical noise which can otherwise disrupt sensitive electronic devices.

• Metal Detectors
• Card Readers
• SERVO Amplifiers
• Proximity Sensors
• Communication Hubs
• Robotic Controls
• Wireless Communications
• Low Voltage Control wiring (0-1mA, 4-20mA, 0-10Vdc, etc.)
• Machine Control Protocols (Devicenet, Profibus, Modbus etc.)
• Video/Security Systems
• Machine Vision Systems
• Flow Sensors
• Air Handling Systems
• Automated Lighting Controls
• Energy Management Systems

Listed below are additional reasons to consider using HFES:

1) ALL VFD’s ARE NOT CREATED THE SAME – It is a fact that all VFD’s are not created equal. There is as much difference in the manufacture and quality of VFD’s as there is in Home Stereo Equipment. Not all design theories will be able to regulate their output to the motor as well as others. In any industry today, manufacturers must constantly evaluate component costs in an effort to remain competitive. The prices of VFD’s in the marketplace today are down from where they were. Reducing costs is a required method to maintain and/or gain market share. Cost reductions can affect VFD performance. Today's technology utilizing switching power supplies do not discriminate. Transient phenomenon, both capacitively and inductively coupled, leak indiscriminately into the system and grounds. In applications where several VFD’s are located together in the same environment, these problems can be multiplied accordingly. Variable Frequency Drive controllers produce a wave shape to the motor that is manufactured by the VFD which is known as a Pulse Width Modulated (PWM) Wave. This wave is different than those produced by your local supplier of power (your local Utility). The main difference is that the Utility supplied power is a smooth wavy line with minimal disturbance being generated along its' path and the PWM wave has multiple square edges. It’s the making of these multiple square edges that create the problems. There are manufacturers who have spent many millions of dollars to study the effects of these PWM wave shapes – and learned to reduce their disturbance(s) phenomenon. These problems can be reduced, but not eliminated. The bottom line however is that ALL VFDs create a disturbance along the wave path, therefore a need for ZERO GROUND HFES.

2) INDUSTRIAL ELECTRICAL DEFFICIENCIES – Today, most manufacturing/business facilities have deficiencies in their Plant Electrical Distribution, and are not aware problems exist. Many plants have older (over ten years old)/outdated electrical systems that need to be upgraded. A once effective electrical system, ten years later, is typically affected by changes over time to the in-house electrical grid. These problems are caused by the addition of new machinery, the installation of switching power supplies, sensitive equipment, changes in electrical service, utility power spikes, surges etc.

3) INEFFECTIVE GROUNDS – Meeting all requirements of National Electric Code Sec. 250 is not difficult. Many systems which were initially grounded correctly, no longer meet technical code. Examples include the fact that many cities have replaced aged metallic water supply meter mains with PVC. These metallic mains, which were once effective in providing grounding, no longer can, since PVC is not a conductor. Cities have already moved to correct this. Bonds, where two different types of metal join, corrode. Aged grounds can and will corrode over time.

4) LIMITATIONS OF ADD-ON DEVICES – Filters, brushes, conductive grease and insulated bearings are just several of many add-on devices marketed to mitigate the effects of nuisance current within the drive/motor system. The effectiveness of an add-on device may be limited by:

Frequency - if operating outside the range of an active limiting device

Effective life - if the device needs routine replacement

Function - for example, if device is designed to mitigate EMI/RFI, it may offer no protection against discharge through the motor bearings or arcing and sparking at physical earth. HFES is completely passive, requires no maintenance, and covers all frequencies and load impedances.

5) LONG LENGTH CABLES – Standard three phase VFD cables exhibit an increasing magnitude of reflected waves over length that can contribute to voltage spikes. Equipment and cable manufacturers’ recommendations vary on maximum cable runs. The specially designed HFES system assembly can support link distances in excess of 500 FT.

6) CERTAIN APPLICATIONS NEED PROTECTION MORE THAN OTHERS – It was recognized early on that certain applications need protection more than others. HFES does not resolve all issues associated with drives /motors installations and is not recommended for every drive application. However, HFES can be successfully used in any application where three phase motors and single phase are utilized, and anywhere EMI/RFI problems are a concern. An installed HFES system is part of a good risk avoidance strategy, where system downtime, expensive equipment replacement, or frequent troubleshooting and maintenance are unacceptable.