EMC-LVD Tests & Applications
Electrical devices have now become a part of our lives with various types and models. Certain compatibility and security regulations are becoming more important with the increased importance of electrical devices in our lives.
Increasing use of electrical devices brings security problems regarding human and environmental health. Certain requirements and tests regarding these standards are taken as basis and implemented for products in order to prevent such problems and secure human and environmental health. On the other hand, certain standards and tests for these standards are being implemented to restrict and control the interaction between electrical devices operating simultaneously, through electrical lines or electromagnetically, control the external immunity of devices and thus, ensure compatible operation of devices simultaneously. Commercial products must be designed in compliance with all such standards and fulfill the minimum requirements of the standards in order to be released in the European Union market.
2. LVD (LOW VOLTAGE DIRECTIVE)
First issued in 1973, the “Low Voltage Directive” includes certain standards that specify the minimum conditions required to ensure human and environmental health. It was put into force in 1990 and covers devices using or generating 50V-1000V voltage in alternative current and 75V-1500V voltage in direct current. The directive specifies standards and tests depending on device type. Devices that fulfill the minimum conditions specified in the standard regarding human and environmental health and the minimum conditions of certain other (EMC) standards are granted with the CE certificate. CE is the certification of the suitability of a manufactured product to the European Union market and was set as a condition for free circulation within the European Union market as of 1990. Its final and current version includes pets and has certain different updates. It was issued on February 26, 2014 and applies for products released to the market after April 20, 2016.
The directive includes “electrical meters”, “information technology devices”, “audio, visual and similar electronic devices”, “electrical devices used at homes and similar places”, “electrical equipment of machinery”, “electrical devices for measurement, control and usage in laboratories”, “uninterrupted power systems” and many other standards. During the project development phase, the minimum conditions should be determined as specified according to the standard under which it is included and the box, material selection, design, protection components / methods should be performed in consideration of these conditions.
There are many tests procedures of which are set under standards according to the directive and the major tests of these standards are as follows:
- Ground Continuity Tests,
- Isolation Resistance Tests,
- Dielectric Isolation Power Test (Breakdown),
- High Voltage Tests,
- Power Measurement,
- Label Endurance Tests,
- Residual Current Tests,
- Temperature Increase Tests,
- Discharge Tests,
- Surface Anti-Residual Protection Tests,
- IP (Protection Against Liquids and Solid Objects) Tests,
- Glow-Wire Tests,
- Ball Pressure Tests,
- Air Conditioning Tests,
- Moisture Resistance Tests,
- Structural Tests,
- Mechanical and Physical Endurance Tests,
- Extraordinary Operation Tests,
- Error Conditions.
2.1 Ground Continuity Test
The ground continuity test is performed between the PE (protection) conductor and the accessible metal parts. The purpose here is to ensure the safety of the product user or the operator during any electrical leakage. For this, a ground conductor and conduction at a maximum distance to such conductor are required in an electrical panel or a machine operating with electricity. Also, it is required that such conduction is continuous. It is required that in the event of any potential electrical leakage on the panel door or the chassis of the machinery, the current flows through the ground conductor for the safety of the user or operator. A constant current is given between the ground conductor required for this and the maximum distance to measure the voltage there. The resistance is measured according to the ohm’s law based on the measured value. The resistance should be lower than a certain value.
2.2 Isolation Resistance Tests
Isolation should strictly be ensured between sections with voltage and sections without voltage in any working environment. In cases where isolation is not ensured, as electrical energy will be present on many points where electrical energy should not be included, this shall cause a major hazard in terms of life safety. This is especially important when devices are operating. Isolation should strictly be ensured between various sections within devices in order to prevent such hazardous situations.
In calculating Isolation Resistance, a constant voltage is applied to the system to be measured and the current value is measured in the system. The ratio of the current and voltage values measured here gives us the “Isolation Resistance”. This value should be lower than a certain limit. Such tests and measurements can also be applied on other separate sections of the electrical equipment.
2.3 Dielectric Isolation Power Test (Breakdown)
A voltage value above the operating voltage of the product is applied on the device for a certain time. The tested device should withstand the voltage it is subject to during such time. The resistance value can not measured in this method.
2.4 High Voltage Tests
The high voltage test aims to test the endurance of the isolation material that prevents contact between the operator and accessible metal parts normally under voltage on the machine.
2.5 Label Endurance Tests
The endurance of the product is tested against chemical environmental impacts specified on its label.
2.6 Glow-Wire Test
The endurance of the product is tested against inflammation/burning of all the parts accessible by the end user. Application temperatures vary here for parts under and not under voltage.
2.7 Temperature Increase Tests
It is checked whether the temperature values of the Product/System fixed under a certain constant load exceed certain limits.
2.8 IP Tests
Tests the endurance of the product against liquids and solid objects in accordance with the minimum conditions required by the standard. The minimum requirements of this test according to the standard may vary from solid objects greater than 50 mm to 8 hours of fine dust test, and from rain in vertical position to long-duration pressurized water test.
3. EMC (Electromagnetic Compatibility)
EMC standards specify the requirements to be applied on all electrical and electronic devices under the electromagnetic compatibility of a device under impact by other devices or malfunctioning other devices. The EMC standards are among the mandatory conditions to be complied with in European Countries since January 1996 and are required for CE certification. Accordingly, no electrical/electronic device should cause electronic propagation that may impact the operation of other devices through electromagnetic interference and should not be impacted from electromagnetic interference. Its final and current version was issued on February 26, 2014 and is valid for products released on the market after April 20, 2016.
The major tests applied under the relevant standards are as follows:
- Immunity Tests Against Electrostatic Discharge
- Radio Frequency with Radiation Electromagnetic Field Immunity Tests
- Electrical Fast Transient / Burst Immunity Tests
- Surge Immunity Tests
- Immunity Tests Against Disturbances Inducted by RF Fields
- Immunity Tests Against Grid Frequency Magnetic Fields
- Immunity Tests Against Pulse Magnetic Fields
- Immunity Tests Regarding Voltage Pits, Short Disconnections and Voltage Variations
- Harmonic Immunity Tests
- Common Mode Disturbances Conducted in the 0Hz – 150 kHz Frequency Range
- Limit Values for Harmonic Current Emissions
- Voltage Fluctuations and Flicker Limit Values
- Discontinuous Interference (clatter), Connection Terminal Disturbance Voltage, Connection Terminal Disturbance Power
3.1. Immunity Tests Against Electrostatic Discharge
Its purpose is to determine performance disruptions that may arise on a device in the event of an electrical discharge through contact with nearby objects. The applied electrostatic load may vary based on the minimum conditions required by the standard. It is applied in two ways, with or without contact.
3.2. Radio Frequency with Radiation Electromagnetic Field Immunity Tests
It is applied to determine the performance disruptions that may arise on a device if it is subject to radio waves in its environment during operation.
3.3. Electrical Fast Transient / Burst Immunity Tests
Its purpose is to determine the performance disruptions that may arise on a device if it is subject to quick recurring changes caused by failures in the mains or by switching.
3.4. Surge Immunity Tests
Its purpose is to determine the performance disruptions that may arise on a device subject to unilateral surges caused by extreme voltages that occur during switching or thunder temporary regimes.
3.5. Immunity Tests Against Disturbances Inducted by RF Fields
Its purpose is to determine the performance disruptions that may arise on a device subject to electromagnetic disturbances conducted from radio frequency emitters.
3.6. Immunity Tests Regarding Voltage Pits, Short Disconnections and Voltage Variations
Its purpose is to determine the performance disruptions that may arise on a device when the mains voltage values drop, disconnect for a short time or fluctuate during the operation of a device.
3.7. Harmonic Immunity Tests
Its purpose is to determine the performance disruptions that may arise on a device subject to existing and recurring harmonics in the mains.
3.8. Limit Values for Harmonic Current Emissions
Its purpose is to measure the current up to the 40th harmonic propagated in the 50 Hz frequency in the power lines feeding the device. The measurements taken here are required to be below the limits set by the standard. Its purpose is to limit/control the disruptive effects caused by the used devices on the mains.
3.9. Voltage Fluctuations and Flickering Limit Values
Its purpose is to measure the voltage fluctuations and flickering caused by a device on the power lines feeding it. Its purpose is to limit/control the disruptive effects caused by the used devices on the mains.
Description was provided here for the standards and certain tests of these standards aiming to eliminate the life and environmental health threat posed by electrical/electronic devices being used more and more every day and to ensure compatible use of the devices. Designs should be made in product development processes in compliance with the minimum conditions required for the free circulation of the product in the European Union market and fulfilling the aforementioned conditions. Time and cost losses can thus be minimized.