The Electrotechnology Mechanical Engineering Engineering Essay

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The installation will be a basic designed with additional points that are not mentioned in the NEN1010:2008 section 7 provisions for special facilities, premises and locations or amended to apply under supervision. The other necessary points for designing the installation should be effective for designing by the standards installation from the NEN1010:2008.

The low voltage standards still describe a wide range from 60VDC till 1.5k VDC. In this section we focus on the 50 VDC till 150 VDC of the Safety Extra Low Voltage in machines (SELV-clusters). The level from 150 VDC can be exceed with consideration with a educated or trained person what the requirements are and how to act unsafe moment, but is out of scope in this chapter.

The objective of this section is to establish a low voltage DC installation for the future Energy Academy.

The installation requirements will try to cover typical house, office and lab equipment, both energy consumers (freezer, dryer, washing machine, fridge, heater) and energy producers (CHP, solar panels, wind turbines).

The different procedures are described in the form of a protocol and have to be adhered strictly for use in the Energy Academy. The parameters provided, such as voltage, earth resistance or other considerations are recommendations based on the available literature and can be modified if it is considered necessary or advisable.

1.3 Personal protection

To apply Residual-Current Device (RCD) with a rated maximum operating current of 30 mA in homes are some key provision in the NEN1010:2008. Clause 411.3.2.5 considered that 120V DC is a potential different from the nominal voltages till earth. The DC's automatic shutdown of the power supply within the time prescribed by 411.3.2.2, 411.3.2.3 or 411.3.2.4 is applicable, but not required if an error on a protective conductor or earth terminal voltage of the source then apply the table of 1 [1] or within 5 seconds (whichever is applicable) or to 120V DC at lower voltage. In such cases, elimination is necessary, not only for electric shock. In the test environment of Energy Academy is the next supplement protection enforcement clause 411.3.3. Here is mention of an AC system but is now used as a DC system. The supplementary protection should be achieved by a device for an earth leakage in accordance with clause 415.1. That goes for sockets with an assigned value (nominal value) of 20 A for general use by leakage and for portable electrical equipment with an assigned value of up to 32 A for outdoor use.

Table 1 Maximum switching off time.

System

50 V < ⩽ 120V

s

120 V < ⩽ 230V

s

230 V < ⩽ 400V

s

> 400V

s

AC

DC

AC

DC

AC

DC

AC

TN

0.8

1)

0.4

5

0.2

0.4

0.1

TT

0.3

1)

0.2

0.4

0.07

0.2

0.04

The switch-off in TT systems through a protective device against over current protective place and settled is connected to all foreign conductive parts inside the system, the maximum tripping prevailing for TN systems.

is potential different from the nominal voltages till earth.

Shutdown may be other reasons than are required for protection against electric shock.

Remarks

If a device for tripping earth leakage occurs, refer to the notes to 411.4.4, 411.5.3 and 411.6.4 in b).

An exception is made for outlets for use under supervision of qualified and adequately-educated operators. This does not apply to homes. Further on, except for the sockets that can only be used to connect a specific electrical device. This means that the contact was not available or by a different model or that means that such an outlet behind a stove or under / behind a built-in oven or microwave is placed and this is not reachable, no obligation needs to be protected by a residual current. This is also not required when using a different socket moderating such Perilex-socket or other odd shaped.

The already mentioned section 415.1.1 establishes that the use of apparatus for earthing safety 415.1.1 states in determining that the use of earth leakage protection devices with a rated operating current not exceeding 30mA in DC systems is considered as additional protection in the event of:

1.A defect in the provision of basic protection, example the failure of the insulation of a device or pipe;

2.A defect in the provision of basic protection, example the failure of the insulation of a device or cable;

3.A negligence of the user, for example, the late replacement of a device or cable with an insulation fault.

For house technology almost always means that all end groups must be protected by 30 mA RCD. The end groups for hardwired appliances obliged under that provision thus secured, it is of course allowed to end-groups with a 30mA RCD protected. NEN1010:2008 section 531.2.1.3 still further provision states that RCD from 30 mA RCD not exceeding more than four end group may connect. On the first page of the NPR 5310 it is better explained and more detailed. Section 4.14 of this document, in which the switching environment and distribution in the meter box will be treated, that provision is further explained.

1.4 Maximum current through cable

The information for maximum current through cable should be research future on with test. This is now done theoretical with emphatic formulas to get information because the test is done in the past. The NEN consider tests for DC house are in the future necessary for confirming the safety. The research is the passed done by the cable company Draka from the Netherlands in Delfzijl.

We consider the two tests blanc cable of a meter and cable isolated in a PVC tube:

Electrical

Type resistend Cu: Ω*m

Diameter cable: Dcu:= 1.784mm

Length cable: lcu:= 1m

Surface cross section cable: Acu = 2.5mm²

Resistant cable:

Thermisch

Radiation constants:

Radiation index of white PVC:

Radiation index of a white oxidation:

Thermal conductivity soft PVC:

Maximum temperature cable: Tcu:= 273K + 70K

Ambiant temperature: Tamb:=273K + 40K

Thickness PVC: hpvc:= 0.7mm

Surface cable: Acable:=Dcu*𝜋*lcu

Surface PVC isolation: Apvc:=(Dcu + 2*hpvc)*𝜋*lcu

The equation below searches the value for maximum current through blanc copper cable for 1m. From the current made power should equal to the thermal given power. The thermal power is delivered by convection and radiation. The part that describes the convection only for a cylindrical object in calm air (1).

(1)

Answer: I = 23.876 A

The PVC coat around the cable isolate not only the electric, but also thermal. The PVC coat causes a deteration from heating pass. It is important that heating resistant from the isolation to calculate.

The equation below search the value for maximum current. From the current made power should be equal to the thermal given power. The thermal power is delivered by convection and radiation. The part that describes the convection only for a cylindrical object in calm air.

Answer: I = 28.312 A

This mean that PVC cover around will give cooling effect on the cable so we can see worst case scenario if there no PVC surround it how much of current go thought the cable.

1.5 TN-System

In TN systems according to NEN1010:2008 section 411, the adequacy of the grounding of the installation depends on the reliability and efficacy of the compound of the PEN- or PE-conductor with earth. If the earth is offered from a distribution net, the network operator responsible for the installation concerned.

The following requirements are:

A) The PEN-line on a number of points connected to earth and is installed so that the risk increased by a break in the PEN-pipe as small as possible;

B)

Where:

is total earthing resistance, in ohms, all parallel earth leakage reds;

is the minimum contact resistance with soil, in ohms, foreign protective conductor a conductive parts not connected, but through which an error between one phase and earth could occur;

is the nominal voltage to earth, V.

1.6 Light installation with low voltage supply

In the NEN1010:2008 section 7 is mentioned of 120V DC installation for the definition from light installation with low voltage the referents to NEN-EN-IEC 60598-1. The information from safety requirements only aloud tills 60 V in NEN1010:2008 section 715.41 safety requirements against electric shocks, but is mentioned the maximum DC value for SELV-light luminaries is still under construction. In the mean time we will adapt the NEN1010:2008 section 715.422.6.2 for safety en take it maximum voltage till 120VDC. With the safety from Low Voltage section X

1.7 Areas for measurement and testing in education buildings

Safety requirement against electric shocks.

Any unshielded measurement setup or experimental setup with more than 120 V DC without ripple must be protected by a separate electrical isolation.

The provision does not apply at that simultaneously satisfy the following conditions:

A) The measurement setup or experimental setup are protected by a jointly control electrical separation,

B) the setup is in the same room,

C) space has isolated or insulated floor coverings

D) not grounded to the measurement setup or experimental setup belonging constitutions and foreign conductive metal parts are protected against accidental contact.

Banana plugs, terminals or the like do see an automatic shielding construction of a security may increase unprotected measurement setup.

Definition 'without wrinkle' clause 410.3.1 'without wrinkle' is defined as an effective ripple of up to 10% of DC component.

1.8 Areas for measurement and testing of portable instruments

In the energy academy are tests done, so the following should be considered in this area:

In places where sockets are used for connecting electrical and electronic instruments and their accessories, should be used of a connection which serves as protective conductor and a functional grounding is united. This connection should have a resistance of a height of 0.1 ohms, measured from the PE connection of the sockets in these places and the earth bus or rail terminal in the switching environment and distribution in the meter box to where the cables is connected

A Faraday cage may be used as guidance and protection combined functional earth from NEN 1010: 2008 sections 543.2.

Other electrical equipment

Single item of electrical and electronic instruments and their need to belong, if there are not of the Class 2 (double isolated), are protected by:

A) SELV-clusters NEN1010: 2008 sections 414,

B) Electrical separation or

C) residual current device for a nominal operating current not exceeding 30 mA.

The size of a leakage current measurement setup, the application of a residual current device having a rated operating current of 30 mA made impossible.

Look for electrical isolation in NEN 1010: 2008 sections 413.

These instruments such separation can be used in:

- factory and workshop.

- Schools;

- temporary measurement systems;

- Laboratories;

- hospitals (for medical locations see NEN 1010: 2008 section 710).

If a c measurement clamp or clamp from functional earthing, possibly through the experimental setup, is connected to ground, should this clamp under NEN1010:2008 section 413.3.6. Not connected with the protective conductor.

On several instruments, the functional earth terminals and protective conductor to be separated

1.9 applying conductor colors

To avoid it is not clear for what purpose wear and veins are used; they must have an indication in the form of a colored insulation. In the European Harmonization Documents (HD) 308 are the colors of the wires in cables and flexible line established for the implementation to five veins.

See Page 39 of NPR 5310 for more information.

In the Netherlands, these color designations adopted for conductor's cables, flexible cables and wires.

By DC there are not standardizing phase colors according from the NEN-EN-IEC 60446 so we consider them. The cable should also tag from end till beginning with numbers for installation drawings.

Across the curious and the veins carry the following colors are used:

Green-yellow protective conductor applies to the PE or PEN conductor in a cable as the PE or PEN-wire.

Blue for the neutral, both veins and wire;

Red for the phase P-DC1 like (L1) wire or conductor or phase conductor switch (only one cable should be used as the red wire circuit conductor);

White for the phase P-DC2 like (L2) wire or conductor or phase conductor switch (only one cable should be used as the white wire circuit conductor);

Orange for the phase P-DC3 like (L3) wire or conductor or phase conductor switch (only one cable should be used as the orange wire circuit conductor);

Grey for the phase wire or phase conductor, well as wire and switch conductor. This goes for both cable and wire;

[1] NEN1010:2008 section 411.3.2.5 Table 41A - Maximum switch off time.

2 Low voltage test installation

This only addresses the important things for the voltage range between the 50V and 120V DC. This range will be used on the electrical DC network of the energy academy, to which the electrical equipment will be connected.

2.1 Applicable standards

The low voltage test installation in this section is adapted and updated from the existing measurements that are mentioned in section 6 of NEN 1010 and NEN 3140. These sections are required and are suitable for these measuring devices. Currently, the Netherlands uses is the standard NEN-EN-IEC 61557: Electrical safety in low voltage distribution systems up to 1kV AC and 1.5 kV DC - Equipment for testing, measuring or monitoring of protective measures. This standard consists of several parts in which the various requirements for measuring equipment are:

Chapter 1 Generally applicable rules;

Chapter 2 Insulation Resistance;

Chapter 3 Loop Impedance;

Chapter 4 Resistance of earth connection and equipotential bonding;

Chapter 5 Resistance to earth;

Chapter 6 Residual current devices (RCD) in TT and TN systems;

Chapter 7 Phase sequence;

Chapter 8 Insulation monitoring devices IT systems;

Chapter 9 Equipment for testing, measuring or monitoring of protective measures

Chapter 10 Combines measuring for testing, measuring of protective measures.

Everything that is not mentioned in this test installation will be refer to the EN 60335 and the NEN-EN-IEC 60204. This is done because there is no Dutch low voltage legislation. The European Union is currently working in the Low Voltage Directive (LVD), but it is not yet finished [4]. The NEN 1010:2008 is still referred to the IEC 61201:1992 - Extra low voltage still active. The IEC 61201:2007 is not active for the NEN1010:2008 or referred, but should replace the older one in the new NEN1010.

2.2 Boundaries

The low voltage standards still describe a wide range from 60VDC till 1.5k VDC. In this section we focus on the 50 VDC till 150 VDC of the Safety Extra Low Voltage in machines (SELV-clusters).

2.2 Objective

The objective for this section is to establish a low voltage test installation to be used in the future Energy Academy lab. This low voltage test installation will give more safety to use or connect in the designed DC grid of section X. This system will take care of the long term measurements and detailed tests, giving a better overview of the safety performance of the different devices and systems.

This low voltage test installation will cover typical house, office and lab equipment, both energy consumers (freezer, dryer, washing machine, fridge, heater) and energy producers (CHP, SOFC, solar panels, wind turbines).

The different procedures are described in the form of a protocol and have to be adhered to strictly for use in the Energy Academy. The parameters provided, such as measurement precision or other considerations, are recommendations based on the available literature and can be modified if it is considered necessary or advisable.

2.3 Test requirements

The low voltage test installation for the (current and future) equipment is to provide for electrical safety in the Energy Academy lab. For every piece of new equipment it will have to be determined whether the combination of components can meet the requirements prescribed under the Low Voltage Directive; proposed in this text, that doesn't exist yet as a standard.

To test responsibly to carry out a number of conditions must be met:

The test environment is suitable (see below, section 2.3)

Measurement devices and the equipment under test must meet the requirements. (Which requirements? - see below section 2.4)

The tester doing the test should know how to test. (any specific demands ?)

National legislation must be observed (like which specific rules or regulations?)

2.3.1 Area test requirements

Where do these requirements come from? If they are from a reference, state why these are appropriate for our purposes too.

The climate in the room must be controlled. The following 9 point should be passed for the area to be suitable#

Parameter

Accuracy measurement

Comment

1

Temperature ambient between 15 and 35 °C [3]

-

2

Relative humidity not exceed 75%

-

3

Presure between 75 and 106kpa

4

No dew. Spray water and- or rain

5

No strong air flow (calm air)

6

No influence from solar radiation

7

Power supply and frequency shall be adjustable over the range indicated on the Device Under Test (DUT)

8

The impedance of the earth must be very low.*

9

The power supply and grounding should be checked on all the requirements **

* reference NEN 2008 section 411.4.1

** reference NEN 1010: 2008 section 61.3.1

Suppose we want to do these experiments in our labs, do these reqs. Give special demands to a building or test lab (like pressure meters?)

Do we need fire extinguishers?

2.3.2 Measurement equipment requirements

The measuring equipment used must be sufficiently precise according to NEN61010. When measuring earth resistance in the DUT is usually the current method. This means that a current of 25 or 30A is sent between the device and its grounding point touchable metal parts according of the EN-IEC 60065. The measuring equipment should be calibrated and traceable to national standard, a Netherlands NKO-calibration. Also there are requirements to the measurement equipment are in the ISO9001 [1]. For example, in normal operation the maximum out- and inputs should be preloaded

2.3.3 Requirements for the tester

The tester should be specialized in electronics, physics and have knowledge from the standards safety and the NEN to test the device. Also the tester must be trained sufficiently on using the measurement equipment. The required technical training corresponds to technical HBO level or higher NEN1010:2008 section 61.1.6 / 61.3.1.

2.3.4 National regulations

The tester will regard the execution of the test must also comply with the requirements of national legislation NEN-EN-60068 - Environmental Testing. This requirement is to ensure the Reproducibility of the results. All countries of EFTA (European Free Trade Association) have the same requirements.

As he/they will work with many open voltages (i.e. touchable voltages) and the DUT temperatures during testing will rise, certain safety precautions should be taken. For The Netherlands the main relevant regulation is the Health and Safety Act (NL titel, referentie ?).

2.4 types of test

From the standards a whole range of tests comes forth. Based on test results can be to determine if the electrical equipment is safe enough. The priority is that operator always is safe doing the DUT.

The DUT does not need to work in a proper way, but the tester should never come into contact with parts under voltage.

The DUT may even completely destroy internal, but may still don't give increased risks for to the user.

The risks are not only electrical but also mechanical and thermal.

This is the reason why testing is divided into three groups:

Electrical test:

Mechanical test;

Thermal test.

2.4.1 Electrical tests

2.4.1.1 Power supply test

Commentaar: (1) volgens mij moet je hier een plaatje of schets toevoegen. (2) qua stijl kun je dit mi. Beter doen met een bullet lijst. (3) ik stel voor dat je ook een voorbeeld "test rapport" toevoegt (template). Volgens mij weet je hier precies wat er moet gebeuren, maar is de presentatie hier nog niet voldoende.

First of all the power should be measured to check if the given power on the machine by the manufacturer is correct over the entire area in which the device can operate. The power should be supplied by a power supply. The power supply should supply a current with a DUT designed VDC ± 10% [3].

Secondly the DUT should test with a low voltage range from 45 till 132 VDC with a frequency change per voltage step from one till 400 kHz.

The DUT is adjusted to maximum power consumption caused by all possible input supply. The switches, potentiometers and functions of the DUT are gradually being put so that the maximum load is obtained. The same applies to the input and output of the DUT. The input and outputs are loaded so that the greatest possible power consumption is obtained

If DUT has a voltage selector, the tester will examine what happens when the wrong power supply is chosen. The DUT should configure with the setting of 45 to 108 VDC and 108 to 132 VDC. First, the DUT on the state put 45 to 108 VDC, 108 VDC while power supply sailing regularly to the 132 VDC. These tests are repeated with a DUT-setting 108 - 132 VDC, power supply while being taken back to 45V and then up to 132V.

The tests are four different configurations that each must be assessed and passed separately. In the first two cases, the fuse melt, because the primary current will, in most cases, double the nominal primary current. Yet it is possible that the fuse remains intact over time. To assess this, the DUT must be for a long time, usually three hours until the situation has stabilized some manufacture recommend for longer test to be sure.

2.4.1.2 Isolation test

The applied insulation material should provide sufficient security before possibility of a shock is possible. The relevant standard reference is NEN1010:2008 section 61.3.3 installation resistant. Such insulation material is tested by a high voltage applied on a disconnected part. The height of this tension will depend on the nominal voltage arriving at the conductor.

The installation passed the installation test if: the test voltage is 1000 volts plus twice U, where U is the nominal voltage.

Example: If it's a conductor with a rated voltage of 120VDC, the test voltage will be two times 120 plus 1000, so this is a 1240V. If there is a component that should provide a galvanic isolation, for example a transformer, stricter measures (which rule is to be followed ?) are applied. The test voltage to be applied in that case can be up to 3400V.

2.4.1.3 Leaking current test

The leakage current is the flow during normal operation of the supply conductors to the earth.

The following three tests should be passed, the DUT has to be working in normal circumstances and the leakage current should not exceed 3,5mA NEN1010:2008 attachment 61A (information):

During this test, the touchable parts are connected only using conductive plastic foil. Depending on the DUT a condition must be created a leakage current is greater as the DUT humidity increases. I do not understand this sentence.

In standards of NEN-EN-IEC 61204 or EN 60355 it is established that the DUT should be for 48 hours in a room with a temperature of 40°C degrees and a relative humidity of 95% before a leakage current be measured. The measurement is performed as an indirect measurement. The appropriate voltage across a resistor phase conductor and earth is measured and then the current flow calculated with law of Ohm's. (picture).

To simulate a human body an RC-network is included in the circuit of the leakage current. The 1500 ohm resistor R should be large, while the capacitor C must have a capacity to hold 1500nanofarad (standard NEN-EN-IEC 60479).

Take after 48 hours the DUT from the climate room and connect it to the DUT specified power supply. It is especially important to consider the frequency, if the system is at a higher frequency, the leakage current will increase. Then directly measure (1) the leakage current between the phase conductors and earth and (2) between ground and earth to both the on state and the off state.

In some cases, the leakage current will exceed 3.5mA. To some extent, than would a more mentioned the DUT of 'beware of increased leakage' (wat bedoel je hier ?)

2.4.1.4 Test with earthing

The earthing from the installation makes the safety of the DUT safer. The earthing is the most important point of the test because that reduces the possibility of shocks. The resistance of the grounding should not be too high according of formula in NEN1010:2008 section 411.4.1. Because of the possibilities that touchable metal parts are under voltage, and then the resistance of the grounding should not be too high.

Measuring the size of the grounding resistance is an indirect measurement. By a current through one or more connections occur voltage drops. Use Ohm's Law to calculate the resistance. The standards generally require that the size of the test current should be 25 A. The current must flow between the basic earth point of the device, (distinguished by the earth symbol or letter PE, it will depend on the type of DUT) and a touchable metal parts. If we want to determine the ground resistance between the basic earth point and a metal bus input plug. According to the standard it may be up to 0.1 ohms.

For example: (use a small picture) Send a current of 25 A by the connection between the base and ground pin input plug. The measured voltage is 2.6 V. The calculated ohmic resistance is following: R = U / I or 2.6 V / 25 A = 0.104 ohms. This value is above the limit of 0.1 ohms. The earth in this case should be improved. The cause of such a situation often lies in the fact that grounded through PCB tracks that are too thin.

2.4.1.5 Component fault or failure.

It should be considered that component fails in critical circuits in according of the NEN-60355. If we lose the transformer, and the secondary side is loaded so heavily that a primary current runs by 110% of the fuse value, the fuse will disconnect the circuit till it's stabilized. The temperature in the transformer goes up, but below the temperature limit of this particular transformer (PCB class) remains.

The range (?) of a ventilator that is used is blocked. The DUT, the temperatures in such cases the limits are not exceeded and must give warning sound and automatic switch of in this case.

2.5.2 Mechanical tests

The protection of touching on the surrounding of the casing used should not increase risk of shocks or failures EN 60065 and EN 60950.

It's required to protect against electrical contact hazard but also against mechanical stress. A case should remain intact even after a possible 'normal' additional load. At a cabinet or against an object can easily fall.

2.5.2.1 Impact test

This test is the so-called "impact test". A ball with a curve with a fixed gear on or against the DUT released. To perform this test is an internationally developed standard hammer. This simulates a ball with diameter of 10mm and a weight of 500 grams to 1 meter from the DUT height falls. The resulting energy is 0.5 Nm. After this test, the enclosure something be put.

2.5.2.2. Drop test

This case must also provide adequate protection as the drop test. If the DUT a brace attached to the DUT is applied, this also demands. Often this will be suitable for a load of 4 times the weight exceeds the DUT. Also, the construction should be able to withstand vibration.

2.5.2.3 Vibration test

The vibration test in many standards is written as follows. The EUT is put down on a vibrating machine with a sinusoidal vibration. The vibration frequency of the vibrating machine is increased from 10Hz to 55Hz and return to 10Hz and amplitude of 0.15 mm. The maximum acceleration will reach around 2G. If during the frequency range 10 to 55Hz to prevent a resonance, then 15 minutes on that frequency tested. There is no resonance in this frequency range, and then 15 minutes 55Hz tested. It's obligated that the construction continues to provide the same protection as for vibration test.

Question: do we need all those tests ? Are they absolutely necessary ?

2.5.3 Thermal test

During normal operation, many parts of the DUT should not be exceeding heat to than a certain value EN 60065. Than a certain value mainly in the following are critical:

The Outside of the housing, button or the handles;

Key insulation;

Primary components.

Thermal tests are usually performed using thermocouples and require relatively large measurement time. The standards require the test to last 4 hours or as long to be executed until a stable situation is obtained. For this stable situation will be set at intervals of five minutes a temperature measurement of the DUT-parts should be done. If three successive measurements show the same result, we can speak of a stable situation.

Incidentally, it is also possible that the placement of the DUT requirements. The DUT should be placed in an angle formed by black-painted plywood with a thickness of 20mm. This reflected influence the heat against it. The rubber feet should be removed from the DUT before the temperature test begins.

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