TO ALL PROSPECTIVE PURCHASERS OF PHASE CONVERTERS AND/OR INVERTERS

An explanation of the issues behind the current difference of opinion between two companies selling phase converters on eBay

Drives Direct Inverters, a supplier of "Digital Phase Converters" has taken exception to comments (see below) which we feel are in the interests of you, the customer. This has manifested itself in the form of negative comments, reviews, guides etc about Power Capacitors Limited and its range of static and rotary TRANSWAVE Converters ®

As a well-established manufacturer and supplier of phase converter products we feel we have a moral obligation to ensure that a prospective customer has all the facts at his/her disposal. We acknowledge that the customer is free to discuss his/her requirements with both our company and its competitors and any decisons regarding the placing of business will be made on the merits or otherwise of those suppliers, its products and the recommendations made.

Back in the 1990s Power Capacitors Limited sold a “Digital Phase Converter” in the UK, Australia and Ireland. The unit was manufactured in the USA by a reputable drives manufacturer with a specialist presence in the UK and Europe. The unit worked on exactly the same principles as the products now offered by Drives Direct. The introduction of supply quality legislation relating to harmonic distortion and CE marking forced the manufacturer to discontinue the product. The products did not comply and contravened the letter of the wording of the supply contract between the electricity supply company and the customer. The only way to make the product compliant was to invest in a harmonic trap which cost as much as or more than the converter itself.

Drives Direct appears reluctant to acknowledge that customers connecting Digital Phase Converters to a single phase supply could find themselves unable to use the product as it does not comply with the letter of the electricity supply contract between the customer and your electricity supply provider.

Such a fundamental issue should not be kept from the customer. Our attempts to bring the compliance issue into the open has resulted in an unjustified backlash.

We trust this clarifies our position and trust that you now understand the reasons behind the issues.

Thank you for your understanding.

*****************

Examples of the wording of our concerns appear below

A QUESTION OF SUPPLY ADEQUACY NOT SUPPLY QUALITY?

There will always be an element of artificiality about the supply that a phase converter produces. The "something for nothing" adage holds true in this market as it does in any other. Static and rotary converters have their drawbacks and cannot offer a solution for every requirement, hence our desire to talk to customers prior to sale.

TRANSWAVE Converters ® offer a proven alternative to the supply of mains three phase for most requirements, however we would always recommend the use of mains three phase where it can be cost-effectively installed. We also advise customers when we do not think a phase converter will meet their requirements.

You can connect a fixed frequency Static or Rotary TRANSWAVE Converter ® to your single-phase supply safe in the knowledge that all you have to ensure is that there is enough supply available to meet the three-phase demand - this is what we mean by "SUPPLY ADEQUACY".

When considering the use of a Digital Phase Converter you also have to consider whether the connection of the device will contribute adversely to the quality of the supply network used by you and your neighbours - this is what we mean by "SUPPLY QUALITY". If the electricity provider consents, then you are free to connect the equipment, if not, the equipment could be disconnected (see below) or you could face further investment to make the product compliant.

We do not have the authority to “prohibit the use of equipment that does not appear to comply with current regulations” rather we would require data to show they were in breach at a specific site. Our position would be that the onus is on the customer to inform us where the device may exceed permitted limits and an assessment may be required. Should we receive complaint or otherwise identify that devices have been connected which are causing emissions outside permitted limits we will require remedial action by the customer or their disconnection in accordance with the procedures laid out in the supply regulations. I realise that this does not resolve all the issues you have with the devices however I would advise thorough testing of any proposed devices to ensure permitted limits are not breached in practice.

Central Networks June 2008

DIGITAL PHASE CONVERTERS - MODIFIED INVERTERS OFFERING 415V 3-PHASE FROM 240V 1-PHASE

A range of “non-standard” single phase input inverters is available for sale on eBay, sometimes referred to as “digital phase converters”. Unlike a standard inverter this type of equipment offers a 415v three phase output from a 240v single phase supply with the aforementioned motor control benefits. All inverter manufacturers offer products with a variable frequency output at 240v three phase from a 240v single phase supply. By limiting the output of these devices to a maximum of 3kW/4hp, manufacturers such as IMO, Mitsubishi, Omron, Teco, Eurotherm ABB and Siemens are able to sell CE marked equipment compatible with European Power Quality regulations.

Digital Phase Converters are modified versions of three phase 415v input inverter products. Modified inverter products do not carry any warranty support from manufacturers of inverters and may require assessment/ approval from your network operating company (i.e. the provider of your single phase electricity supply) prior to connection. The modified product has no CE Marking and therefore does not comply with EU EMC regulations. Tests on this equipment confirm that acceptable levels of harmonic distortion are exceeded and thus a CE mark cannot be applied.

If you are considering the purchase of a modified inverter/ digital phase converter, we would recommend that you contact your NOC or Electricity Provider and investigate the financial consequences of making the product compliant with appropriate EMC and power quality legislation BEFORE YOU PURCHASE.