FAQ – Frequently Asked Questions

Find answers to some of the more frequently asked questions we receive.

Do I need a Voltage Stabiliser or Power Line Conditioner?

There is no official definition of a Power Line Conditioner and often it is confused, by users and specifiers, with the term Voltage Stabiliser.

Most informed commentators agree that In essence both a Voltage Stabiliser and Power Conditioner should protect against voltage transients, spikes, sags and brownouts (voltage fluctuations), but in the case of  a Power Conditioner it should also offer, through the inclusion of a shielded isolating transformer, additional protection against Electrical Noise and a higher level of defence against transients and spikes.

As such a Power Line Conditioner will only be required if protection is also need on site against electrical noise, or it is specified that a ‘Clean’ supply must be provided. If you do not have an  issue on your site with Electrical Noise, what you require is simply a Voltage Stabiliser – the more cost efficient solution.

For us at VSI the inclusion of an Isolation Transformer is an add-on option that is offered on all ESR Series Static Electronic Voltage Stabilisers.

NB: It should be noted, with confusion over the exact definition of a Power Line Conditioner, some competitor products marketed as Power Conditioners do not in fact  actually offer automatic voltage regulation. With a wide variation in capability between products it is imperative that a buyer does his or her homework to determine site application requirements and when comparing alternative options matches carefully product functionality.

What Output Voltage Accuracy do I actually require?

Voltage Stabilisers are intended to stabilize / regulate the utility mains voltage when it fluctuates, up or down.

They are essential whenever reliable power is needed, or when normal operation of electrical or electronic equipment is disrupted by voltage variations.

In general when suppliers of today’s modern electrical and electronic equipment design their products they do so knowing that most electrical utilities around the world cannot provide or promise better than a ±5% output voltage accuracy of nominal and as such they design their equipment so it is able to operate efficiently within this range.

Our ESR Stabilisers are specifically designed to meet the requirements of today’s modern loads, being feature rich and virtually maintenance free static mains control solutions. They ensure the availability of a constant voltage at a level that always meets the design requirements of the load equipment, even for the most challenging of power environments or site loads.

Configured for optimal energy efficiency and design life expectancy, ESR are supplied in general by default with the output voltage accuracy set for ±3%, being easily site-adjustable to deliver a more or less precise output voltage accuracy – as considered most appropriate for a particular site’s needs.

What is the design topology utilised in your Stabilisers?

ESR-Schematic-Revised-April-2016Based on the extremely well proven traditional Buck Boost design topology, ESR Static Voltage Regulators utilise SCRs (Silicon Controlled Rectifiers) to select transformer taps to deliver a highly stable output voltage with an extremely fast correction time.

Unlike more common Electronic SCR based solutions, the underlying Buck Boost topology ensures that the SCRs are not required to handle the full load current, but merely a fraction of the load current. By suitably sizing the ratings of the SCRs, ESR Stabilisers are able to deliver impressive overload capabilities and considerable enhanced reliability.

The utilisation of the latest in microprocessor control and the inclusion as standard on all models of an input circuit breaker, ensures that the SCRs are fully protected against  over-current conditions and other malfunctions, which historically have been viewed as the primary weakness of Electronic based SCR solutions.

Where are your Stabilisers manufactured?

Our Stabilisers are UK engineered solutions, with manufacturing, as is common in the power electronics industry today, outsourced to Shenzhen, China.

Working closely with and under the supervision of staff from our Hong Kong office, our manufacturing operation in Shenzhen ensures we are able to deliver high quality product at internationally competitive prices.

How can I buy your products?

You can buy direct from ourselves, or in countries where we have representation through any of our growing number of authorised resale partners.

If you would like to learn more about the reseller opportunities available with VSI please feel free to contact us.

How do I get a Quote?

All requests for a Quote or Price should be made directly to ourselves.

Requests can be made in the following way –

Email:                   Drop us an email advising your exact requirements and also full contact details.

Online Form:      Complete our Online Request for Quotation Form.

Telephone:         and of course, you could just simply give us a call !

Upon receipt of your enquiry if we have an authorised resale partner in your region, who is ‘best suited’ to deal with your exact requirements, we will introduce you to them and working together we will present a formal proposal for your consideration.

How long will it take for me to get a Quote?

We always strive to turn around quotations within 2 to 3 working days, but at certain times this may take slightly longer, especially if multiple options and / or additional freight costs are requested.

Can I get a Price List?

Strict company policy does not permit the issue of product Price Lists other than to authorised resellers / distributors or for specific client project requirements.

If you would like to give us details of your specific requirement we would be happy to quote you accordingly.

What is the process for place an Order?

To place an order we would request that you simply send us a formal Purchase Order, or if more appropriate an email accepting the proposal we have made.

Upon receipt of your instructions, if you do not have prior agreed credit facilities with ourselves, we will send you a Proforma Sales Invoice requesting payment in accordance with terms stipulated in our proposal.  A speedy settlement is recommended so we can confirm the build order on our factory or stock allocation at the relevant distribution centre.

Our standard payment method is Electronic Funds / Bank Transfer,

Within 2 to 3 working days of getting this payment, or receiving an order from an approved credit account holder, we will send you a formal Order Acknowledgement detailing our interpretation of your requirements and confirming the anticipated dispatch / delivery date. If you do not agree with our interpretation of your requirements we would request that you advise us of the discrepancies within 24 hours.

What are your terms of carriage?

When quoting UK or European clients our prices are normally either on a DDP basis – delivered their offices (Kerbside) – or Ex-Works / Export Packed our UK Distribution Centre in Sunbury-On-Thames, Middlesex, UK (14 miles from London Heathrow Airport) –  being either in GBP £ or Euros € (as applicable).

For all Other Customers prices are general quoted in US $ on an Ex-Works / Export Packed our Hong Kong Distribution Centre basis – with air or sea freighting charges to the clients local sea or airport being quoted as billable additions.

For US and Canadian mainland clients we are also able to offer pricing on a DDP basis – delivered their offices (kerbside) with all duties and taxes paid.

Should any of our customers wish to handle their own freighting, with their nominated shipping agents collecting the goods from our Hong Kong Distribution Centre this is not a problem and most of our quotes show the anticipated packing case sizes and weights.

What is the relevant Tariff Number (HS Code) for your products?

VSI products are normally classified under the following HS Code –

9032.89.4000      Automatic Voltage and Voltage-Current Regulators


FYI – The Harmonized Commodity Description and Coding System (HS) of tariff nomenclature is an internationally standardized system of names and numbers for classifying traded products developed and maintained by the World Customs Organization (WCO) (formerly the Customs Co-operation Council), an independent intergovernmental organization with over 170 member countries based in Brussels, Belgium.

On International shipments what does your Standard Shipping Documentation include?

Normal standard commercial international shipping documentation includes – Commercial Invoice, Packing List and Airway Bill or Bill of Lading.

Any Third Party Conformance Certification, Certification of Origin or Legalisation / Attestation of any documents can be provided on request – being subject to additional charge.

As soon as available after shipment, soft copy of the documentation will be emailed to the client. Unless requested to the contrary, all sea freight Bills of Lading will be provided on an Express / Surrendered basis and the original documentation for air freight shipments will be attached to the consignment in a clearly identifiable pouch.

Should a client require the original documentation to be couriered under separate cover this can be arranged on request – being subject to additional charging.

Can your packing comply with the requirements of the ISPM 15 Directive?

Yes. Should a client require a formal Heat Treatment / Fumigation Certificate for a particular shipment this can be arranged with due notice – being subject to additional charge.

Need more help?

While every effort has been made to make this FAQ as informative as possible , if you have any questions that we have not answered, or you require clarification on any points arising, please feel free to contact us by using the quick and simple form below –

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