A Practical Guide for erection and operation of electrical test equipment According to EN 50191

Introduction Testing of the electrical devices during the production process is one of the fields in the more general electrical equipment testing. It requires special attention to the operator's safety. Test procedures require application of very high and dangerous test voltages, which cause heightened probability of electric shock. There are numerous types of electrical equipment that need to be inspected and tested during the manufacturing process. Metrel has developed a special model MI 3394 CE MultiTesterXS machine safety tester. With its safety modules and optional accessories it conforms...

Table of contents 1. Working places according to EN 50191 2.2.2. Allowable alternatives – when IP3X can be omitted 11 1.1. Scope of this document 2.2.3. Other possible omissions 1.1.3. Conditions where conforming to EN50191 is not required 1.2. General protective measures in test installations 1.2.1. Protection against direct contact 1.2.2. Protection against indirect contact (fault protection) 2.3. Test station without automatic protection against direct contact direct contact 4.3. Test station without automatic protection against direct contact 4.5. Temporary test station Permissible body current...

1. Working places according to EN 50191 1.1. Scope of this document This document is intended as a help when making work stations for testing safety of electrical equipment. If dangerous voltages, currents, residual charges and other hazard can occur in the work place the standard EN 50191: Erection and operation of electrical test equipment should be considered. Warning: This document is additional help with understanding the standard. It shall not be used as a substitute for the standard or other required documents. It does not reflect all points covered in EN 50191. • Test stations in operation...

1.1.3. CONDITIONS WHERE CONFORMING TO EN 50191 IS NOT REQUIRED EN 50191 states that compliance is not necessary if contact with live parts of the work place presents no danger. This is true under one of the following conditions at live exposed points: values for permissible body currents and contact voltages will be taken from Table A.1. d) The discharge energy does not exceed 350 mJ. a) The voltage at frequencies above 500 Hz does not exceed 25 V a.c. or 60 V d.c. and complies with the requirements for SELV or for PELV in accordance with HD 60364-4-41. b) In case of voltages at frequencies up...

1.2. General protective measures in test installations In this chapter the key elements of protection in test installations are described. 1.2.1. PROTECTION AGAINST DIRECT CONTACT Protection against direct contact is the essential and the most important protective measure. It can be made by: • insulation of live parts everywhere in the installation (on test object, test equipment and test connections). • Assuring safe distances to live parts with barriers, covers, enclosures, obstacles etc. • Using two hand control devices that comply with EN 574. • Using two safety test probes. Clamping devices...

area from other work areas. Their purpose is to prevent people other than the test personnel from: • accessing to the test area, • reaching the prohibition zone, • reaching the operating devices inside the test area. The minimum space the barriers provide are defined in Annex A (Table A.3 and Table A.4) of EN 50191. If barriers are conductive, they must be earthed or otherwise protected against indirect contact in case of fault. 1.2.5. USE OF INDICATOR LIGHTS, SIGNAL LIGHTS, WARNING SIGNS Indicators, lights, or signs on the control panels inside the test area should indicate the switching status...

2. Types of test installations 2.1. Test installation The test installation is the combination of all test devices, appliances and facilities necessary for testing. When designing a new work place the type of test installations needs to be defined. A test installation can be performed as: • Test station with automatic protection against direct contact. This type is common on serial production lines, and is also preferred in workshops, repair and service shops. • Test station without automatic protection against direct contact. This type is common in workshops or laboratories. The test station...

2.2. Test station with automatic protection against direct contact This is the preferred test installation type. Test station with automatic protection against direct contact is the preferred choice when setting up a work place. There are very few justified reasons to choose a different type and they are collected in in EN 50191, chapter 4.3.1. Mainly different types are chosen where automatic protection against direct contact is not possible or economical. 2.2.1. ARRANGEMENT OF AUTOMATIC PROTECTION AGAINST DIRECT CONTACT Protection grade of IP3X or higher Appropriate isolation (achieved with...

Comments in BGI 891 (chapter 3.2.6) According to EN 50191, one still effective protective measure in case of a single fault is enough to protect against indirect contact. For the test and measuring equipment, protection in case of a single fault must be guaranteed by design (with CE declaration - LVD, IEC/ EN 61010). However one protection in case of a single fault does not provide 100% safety. If another fault occurs, or in case of a combined fault, there is still a possibility of a dangerous electric shock. It is possible to make test installations with a higher degrees of protection. For example,...

distance between beams not more than 14 mm can be used instead of the enclosure. Safety distance between the prohibition zone and detection zone, approach (breaching) speed and respond times of the protection/ switching devices must be considered. Instructions for calculation can be found in EN 999 Safety of machinery - the positioning of protective equipment in respect of approach speeds of parts of the human body. Solid walls or grids Barrier with height of least 1.8m (with mesh size < 40 mm or solid wall) must be placed as a barrier to the prohibition zone. Distances are given in EN 50191,...