The LV-Directive (2014/35/EC)
As all ce-related directives this is a new-approach directive, which means that only main requirements (essential requirements) are required. The LV-directive shows the way of showing compliance to the main requirements. Themanufacturer may assess the safety of its product or apparatus by applying a standard from the list of Harmonised Standards
In addition since june 2016 a risk analysis is required.
The manufacturers declaration consists mainly of a liability statement (Declaration of Confomity DoC) made up by manufacturer or importing agent in which he accepts the legal consequences (liability) for conformity of its equipment to the essential requirements from the LVD. The manufacturer is granted permission to do the assessment himself, or let the testing be carried out by any test-house. Using this route the manufacturer is strongly suggested to use the so-called Harmonized Standards for type testing, although in absence of these any other safety standard or no standard at all may be applied.
Technical Construction File (TCF).
In order to prove compliance to the essential requirements of the LVD one has to make up a Technical Construction File. This includes all safety related topics, such as precautions, instructions, test reports and everything necessary to identify the apparatus, such as circuit diagrams, mechanical drawings and detailed part lists. The mandatory risk analysis may be part of this file.
The LVD is not just limited to electrical shock and insulation only.
Once an apparatus falls into the scope of it, many other aspects of safety like fire hazards, mechanical hazards, radiation and chemical hazards are part of the approval procedure.
Basic Safety Concepts
Protection against electrical shock
Electrical safety is implemented using the concept of double safety layers:
1. Insulation + Grounding
2. Insulation + Extra Insulation (double or re-enforced insulation)
Any part at hazardous voltage should be separated from the operator/user by 2 layers of safety as specified under 1. or 2. In addition to this the failure of one layer may not affect the initial safety of the equipment. Operator safety must be achieved with one layer only. The approach of testing whre one layer of safety fails is called SINGLE FAULT TESTING. Evulated are the effects of (among others) :
Misuse (foreseeable abuse) of an equipment is also considered as a single fault.The LVD approval procedure is based on the utilization ofin all applicable circuits (most important in the mains circuit). This implies that all parts having a safety function need an examination to their specifications and (if applicable) need a ce-declaration (or better) available, before they are allowed in the construction of an apparatus.Component manufacturers in generally are not very cooperative in producing accurate declarations, as a ce-declaration of conformity involves direct liability of the manufacturer for the safety of it's components . A UL, CSA or VDE declaration -although very valuable- is a testimonial declaration and not a manufacturers declaration: less liability for the manufacturer is involved. Most US originated OEM equipment lack sufficient component safety (for use at 230vac) due to the difference in mains voltage. Although manufacturers may specify a component as being suitable for 230 Vac, this does not imply that the same component is safe at 230 Vac. In order of relevance we require safety certificates from (for your applied components with a safety function)
What components do have a essential safety function ? In general, all components carrying mains voltage and all components carrying a hazardous voltage to the operator have a essentail safety function. Even more general, all components carrying any hazard in them may qualify as such.
Many more requirements exist considering hazards associated with heat, fire propagation, radiation, mechanical hazards (sharp edges), short circuits, leakage current (touch current) and more.
The electrical safety test procedures are not to be underestimated !
This list of standards is an ever increasing subset of world-wide existing standards, that due to their way of defining test-methods, limits and susceptibility criteria, are very well suited for testing by the manufacturer himself, or by any test house using the right equipment.
This list of standards is updated approximately once a year.
The Declaration of Conformity is most often based on one sample of a "type tested product" that ideally should be identically reproduced in series. In order to maintain safety in real life production, some quality control is imperative. The LVD specifies the requirement of such a scheme. Therefore each and every produced apparatus must be verified for a number of essential parameters -composed by your test house- such as functionality, dielectric strength , the grounding qualities and potential pitfalls created by foreseeable mistakes in production.This focuses the attention on those faults that are easily made without being detected in functionality tests, and that may create a potential hazard to the operator. Examples are grounding clips, insulation barriers, warning labels, insulation (rubber) rings below ring core transformers etc. In general, safety measures should be applied exclusively for the safety purpose, and should not share any task with functionality , unless the safety measure is very obvious. Safety features must be visible and easy distinguishable from functional features.Safety measures should not be compromised during normal operation and service. Routine test must be logged, therefore serial numbering your equipment is required. Standards exist for setting up these so-called routine tests::
Your test house will be helpful in selecting a routine type test protocol.
Most popular failures....
Although exceptions exist, the insulation between metal (accessible) parts and hazardous voltages (mains) must be no less of 4 mm and up to 8 mm in medical equipment. It's very easy to compromise these distances especially on printed circuit boards.
Not only equipment but also components must be tested for safety. Most components comply to international IEC or EN standards. Equipment brought to Europe often uses UL or CSA approved components.
IYou definitely have to make sure that your components are suitable for European voltages and make sure they are sold to you with written proof of compliance. Just a catalogue page showing the ce mark in the corner won't do ! If it's writing "designed for (to) comply with .[standard].. ' or "tested for [standard]...." , then you can be sure the part is not compliant. Look for the phrase: "Compliant with [standard] " and then don't forget to check it's the correct standard and not an obsolete one.........! Correct part number and applied standard are best be mentioned on a signed document.
You must have seen that in your product's Bill of Materials: many parts have no specified type or manufacturers name behind them. How can you be sure that this part performs the required function, and how can you declare liability for the safety of those parts ?
All equipment should ideally be accompanied by the following documents:
Of all these parts the safety part MUST be translated in the language of the country you are selling to. Many countries require other parts to be translated too. Several parts may be contained in one volume however, but we recommend a separate sheet for those safety aspects that require immediate attention when opening the box... should we mention why ??
Let us quote you for your product and get all this and more taken care of....