Category Archives: Electrical Testing and Verification

Electrical Testing and Verification, Electronic Devices Assembly

Solar panels installation for homes

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DIY Solar Panels hook Up

solar panels Installation
solar panels

Photovoltaic solar panels convert sunlight directly to dc voltage. This is useful to power devices directly as it were or convert to alternating current voltage through an inverter. This article focus on different methods in use to hook up solar panels to batteries; appliances; electric motor; and mains power outlet.

Hooking up Solar Panels to Batteries

The cable which connect to solar panels through solar cable entry box is two and similarly power inlet to any battery and dc appliance is two. So you may connect your solar panels directly to any rechargeable batteries. You can connect to your appliances without damage. In doing this, however you have to follow basic instruction to do it right.

  • The voltage from the solar panels must match the voltage of the battery for instance, you need a 12V panels to charge 12 Volts batteries.
  • The size of the solar must measure up with battery size. A big size panels will supply excess power to tiny battery in bright sunlight.

Solar Panels Voltage Output

Voltage output of a solar panel is dependent on the sunlight. Open circuit voltage output of panels in full sun is almost twice the voltage of the battery  to charge. Solar panels produce power at their maximum power point, which is usually about 60% of the open-circuit voltage. For example, if you have a 12V solar panel, open-circuit voltage in full sun is about 24V. You need to consider the capacity and voltage of your panels as well as the size of the batteries. You need panels that will put 5% (at least) of the ampere hours capacity of the battery in as current. For example, if you have a 100 amp-hour battery, you’ll need enough panels to put 20 amps in at the voltage of the battery.

You can connect many batteries with the same voltage in parallel to get more amps and more watts. You can also connect batteries in series to get the voltage your inverter needs. But most cheap inverters have 12 volts input, and work from 10.5 volts to about 14.5 volts. However for your battery to last long the system needs well designed. In situation when you have deficit of sunlight for a long period, a user tends to continuing using the batteries at great risk therefore it is necessary to include a low voltage battery disconnect devices in the design.

Solar Panels Battery System

The battery might be a wet Lead Acid, Gel type or deep cycle all the same in this regards. A fully charged like new car battery or other about that size will supply about 1000 watts briefly, so you should not expect to run appliances rated more than 1000 watts except with a very large battery.

The battery voltage needs to match the appliance’s voltage for appliances using low voltage direct current from battery. But most equipment require 110V/220V which means you need an inverter. Th inverter should voltage of your battery as input and the voltage of your appliance as output. A 1000 watt inverter rated about 2000 watts surge is probably best, but other inverters will probably work. Typically they have full protection from user errors, and turn themselves off if conditions are not right. If you have the voltage correct the appliance will draw the current and watts the appliance needs. That is f the inverter and battery can supply that much current and watts.

Connecting solar panel directly to a battery?

When connecting solar directly to battery without a charge controller, it is OK to put a diode in the line. A diode is an electrical check valve, allowing current to flow in one direction only. This will allow the panel to charge the battery, but not let the battery discharge into the panel at night. Most panels today come with diodes already installed in the junction box.

The panel voltage, or “Open Circuit Voltage,” should be higher than the battery full charge voltage. If the 12V battery full charge is 13.5V,  panels’ wiring are for 18 volts. Then they can charge a 12 volt battery. The panel voltage will simply sag to match the battery’s charging curve voltage during the daytime.

Second, if the panels max amps, or, “Short Circuit Current,” rating is below 2% of the battery’s amp hour capacity, then the panel will never overcharge the battery. For example, if the battery is 75AHr and the panel short-circuit current is just 1.5A, then the panel can never able to overcharge the battery which means you may connect the battery directly to the panels or vice versa. A panel in direct sun without anything hooked to it should put out about 17 or 18 volts, unless the wiring is for some other nominal voltage other than 12. For example, if you have a 50W panels with maximum amperage of 6 amps, to charge a battery which wired for an amp hour capacity of 440 AH, you are well within the 2% window, you may not use a charge controller.

Ensure that you keep the batteries watered at least once a month with distilled water, they will go through some electrolyte this way.

How to connect a solar panel to a motor?

A solar panel cannot operate a motor by itself. A typical system operates like this: The solar panel is connected to a charge controller. The charge controller is connected to a battery which is connected to a motor controller. The motor controller is connected to the motor. All these components must be compatible with each other. So, in other words, you can’t run “just any old motor” with a solar panel. Typical use is a system like an solar powered electric gate opener

How Connect Power Outlet to Solar Panel?
  • Determine Your Power Requirement

The use of energy-saving lights like solar tubes or sun tunnels or LEDs gives you the same light output for 100W as incandescent lights of 500W is most efficient; this means you can have much light for less number of solar panels. Then you need a solar panel that can produce 100 watts for as long as you want (at a 100 watt lighting system) or 200 watts for 1/2 the time you want, etc. Allow a good 10% or so for inverter inefficiencies, and 10% or so for reserve, so 120 watts per 100 watts.

After you have this, you will want

  • A Charge controller,
  • A Battery, or Battery Bank with enough amp-hours to support your system, plus a good 10% or so reserve, plus another 10% or so for inverter inefficiencies (remember the over sized solar panel above, this is why),
  • then of course you also need a 12-volt DC to 120-volt AC, 60 Hz system (or 240 volt AC 50 Hz system, depending on your AC system) inverter. The battery should be deep-cycle series between 2, and parallel between banks of 2 for the 12-volt portion of the system.
Voltage Controller Vs Charge Controller

Charge controller is for charging batteries with a high current array while Voltage controller sends solar power directly to a device like a water pump. In this case, you don’t connect a solar panel directly to your device it must pass through a voltage controller when you don’t involve battery in the system. The most efficient charge controllers use what’s called Maximum Power Point Technology (MPPT) which lets the panels operate at their most efficient point throughout the battery’s charging cycle.  The charge controller should have the same or higher wattage as the panels it controls – if you’re not sure of wattage, assume that they are the same as similar area panels you find for sale

  • In summary,
    You can connect solar panel directly to battery through a diode if the panel short-circuit current is about 2% of the amp hour ratings of your battery.
  • If the array Short Circuit Current is higher than 2% of the AHr of the battery bank, then you will need a charge controller between the battery and the solar panel.
  • The open-circuit voltage of a 12v panel is about 18v which is sufficient to fully charge a 12 v battery to its maximum at 13.5v to 14.5v.

You can add solar panels in series for high voltage; you can add solar panels in parallel for high current output depending on your application. To connect panel(s) to a device or appliance, you will need a voltage controller between the panel and the device.
You can minimize number of panels for your output by using energy efficiency appliances especially for lighting.

Tags:

Charge Controller; Voltage Controller; Deep Cycle Batteries; Diodes

References:

Source(s): http://www.azsolar.com/catalog/item/1496…
Homepower.com
Midwest Renewable Energy Association MREA.ORG
Solar Energy International, solarenergy.org

Electrical Electronic Design, Electrical Testing and Verification, Practical DIY Electronics

Dimmer Switch Replace How to Install

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Dimmer switch replace for small appliances like laboratory microscopes, slit lamps, and others as you may think of, Sometimes, the circuit is bad and its taking too much time to find out the problems in the course of diagnose. Find below the schematics diagram for a dimmer switch replace suitable for a low voltage appliances. It is a  Pulse Width Modulation based module suitable for light source of Microscope, Slit Lamps and portable light source. Meanwhile, for small DC electric motor and lots more.

You could actually ask for a replacement dimmer switch from the manufacturer of your product, But if you still have warranty on the appliance, the manufacturers or suppliers would be in a position to help in the repair or replacement.


dimmer switch replaceAbout the Schematic

The circuit module above consists of three circuits put together. The circuits are 12 volt positive regulator, an oscillator, and a voltage comparator. Other are an integrator, and a driver. The oscillator and the integrator employs an LM324. The comparator is also one of the LM324 package with supporting components.

For this circuit to work, you need a source of unregulated dc power supplies or a battery. Besides, the PSU should be more than voltage of the ic regulator. For example, if the Ic voltage regulator is 12V as shown in the schematic, then, the PSU voltage should be at lear 2.5 volt more than 12 volt. That is, 14.5 volts. Learn more about unregulated power supply unit.

Meanwhile, for more information regarding for specifications; theory; construction; alignment/calibration/configuration; how to use and Bills of Quantity, check here Motor Speed Controller and or DC Light Dimmer (2016_06_01 10_11_06 UTC). 

We can adapt the simple dimmer schematic to control high power load by simply change few components. The main component to change is the Field Effect Regulator (FETs) and the fuse.

Electrical Electronic Design, Electrical Testing and Verification

Add IC Voltage Regulator to Wall Adapter

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How to Add IC Voltage Regulator to Wall Adapter/Battery

Often what you required to run an equipment or device is a well-regulated source of DC power.  To do this, you need to add ic voltage regulator Regulated power supplies gives out stable desired voltage output. You will even need one for your projects. In its simplest form they call it a battery eliminator. For some application the simple battery eliminator is less desirable. Therefore, you need a well-regulated for equipment from batteries and from a wall adapter that outputs a DC voltage

add IC voltage regulator

You can construct a well-regulated power supply. To do this, you add a voltage regulator IC to ordinary DC output from wall adapter or a battery. The voltage regulator is either a fixed type positive (+ve) or negative (-ve). Available also are adjustable voltage regulator. The regulated power supply unit finds application where you require stable power output. They are to power device such as indirect ophthalmoscope, portable light source and host of others. It also functions as a small power supply unit for electronics experiments.

Example for add IC Voltage Regulator:
  • 78xx typical example: 7812 is a positive 12v fixed voltage regulator IC. For example 7805 voltage regulator IC
  • 79xx typical example: 7912 is a negative 12v fixed voltage regulator IC
  • LM317 Adjustable positive
  • LM337 Adjustable negative

The ic voltage regulator for example LM317 looks like power transistor but is a complete regulator on a chip.

Here is a typical circuit:    It is important to identify the pinouts to add IC voltage regulator and to use it appropriately. Here are pinouts for the most common types:

Note: Various manufacturers may label the pins differently than shown. Best approach is to check the datasheet if you are in doubt.

Design Information to add Variable IC Voltage Regulator

For the LM317 circuit above,

  1. R2 = (192 x Vout) – 240, where R2 in ohms, Vout is in volts and from design it’s between 1.2 V and 35 V.
  2. Vin is at least 2.5 V greater than Vout. Select a wall adapter with a voltage at least 2.5 V greater than your regulated output at full load. However, note that a typical adapter voltage may vary quite a bit depending on manufacturer and load. You will have to select one that isn’t too much greater than what you really want since this will add unnecessary wasted power in the device and additional heat dissipation. For example: if expected maximum Vout is 15v. Then R2 = (192 x 17) – 240 = 2,784Ω or 2K8. Vin, then is at least Vout + 2.5v = 17 + 2.5 = 19.5v
  3. As indicated in its data sheet, maximum output current for LM317 is 1 A. Your adapter or battery must be capable of supplying the maximum current safely and without its voltage drop below Vin + 2.5v minimum as declared in 2 above.
Choice of Capacitor
  1. You may add extra filter capacitance (across C1) on the adapter’s output to reduce its ripple and thus the swing of its input. This may allow you to use an adapter with a lower output voltage. This also reduce the power dissipation in the regulator as well. Using 10,000 uF per “amp” of output current will result in less than 1 V p-p ripple on the input to the regulator. As long as the input is always greater than your desired output voltage plus 2.5 V, the regulator will totally remove this ripple resulting in a constant DC output independent of line voltage and load current fluctuations.
  2. Select a capacitor with a voltage rating at least 25% greater than the adapter’s “unloaded” peak output voltage and observe the polarity! For example, if the “unloaded” peak output voltage is 19.5v as calculated for the Vin in 2 above, then voltage of the filter capacitor would be 19.5v + 25% which is approximately 45v.
Note:
  1. Wall adapters as battery eliminator may not have any filter capacitors so we will need IC regulator with this type. Quick check: If the voltage on the adapter’s output drops to zero as soon as it is pulled from the wall – even with no load – it does not have a filter capacitor.
  2. The tab of the LM317 ic voltage regulator is connected to the center pin – keep this in mind because the chip will have to be on a heat sink if it will be dissipating more than a watt or so. P = (Vout – Vin) * Iout.
  3. There are other considerations – check the datasheet for the LM317 particularly if you are running near the limits of 35 V and/or 1 A.
  4. For a negative output power supply, use the corresponding negative voltage regulator and note that their pin-out is NOT the same as for the positive variety. See above!

For any support in your design and construction or you get stuck somewhere to add ic voltage regulator, simply Contact Us describe in details how we may help.

Reference:

Various Schematics and Diagrams

Reproduction of this document in whole or in part is permitted if both of the following conditions are satisfied: This notice is included in its entirety at the beginning. There is no charge except to cover the costs of copying. Introduction High Voltage Power Supplies – Home-built and commercial units.

Electrical Testing and Verification

Suction Apparatus and Suction Machine

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A suction apparatus and suction machine is commonly found in the emergency room, the operating room (OR) and clinical wards. To begin with, it extracts fluids such as saliva, vomit and spittle from unconscious patient. This is normal during surgical operation and air from the bronchial airways and postoperative drainage of sites. This is done through tubing and catheter into a suction bottle also known as  canister or reservoir.

The reservoir is normally made of glass or clear solid plastic with markings indicating volume.

Types of Suction Apparatus and Suction Machine

There exist different types of suction apparatus named according to area of application such as for pediatrics, O and G, and for general use. Similarly, some are electrically, vacuum and battery operated. Another category of suction machine are high or low pressure.

Low pressure suction machine is useful in gastrointestinal drainage such as bleeding in the stomach or intestines. The low pressure suction should drain the body fluid in a continuous manner without damaging the underlying soft tissues.

However, the most commonly among suction machine is the electric types. Good for different characterised accuracy and ease of use. This type is usually portable and last longer. Seen below fig. 1, is a portable battery operated suction machine with facilities for recharge of embedded batteries.

Different Components of Suction Apparatus

Components part of Suction MachineThe three important parts of a suction apparatus could classified as:

  • Source of Vacuum which is basically a vacuum pump;
  • The Reservoir which includes one or two suction bottles or canisters and
  • The Delivery Tubing which is a length of flexible plastic tubing which may include a nozzle or a catheter.

Equally important components which makes a suction pump complete are:

  • Bacterial Filter;
  • A Vacuum Gauge;
  • Vacuum Control Valve and
  • Vacuum Cut off Valve and
  • Moisture or Debris Trap.

The efficiency of a suction machine depends on the displacement or the volume of air the pump is able to move. This is usually expressed in liters per minute (l/min). Meanwhile, efficiency is also affected by negative pressure produced by the pump with particular regards to the time taken to achieve it.

A Typical Use of Suction Machine

Airway and Secretions: A tracheotomy is a surgery performed by doctors by inserting breathing tube within a patient’s windpipe. This surgery performed on adults and children and it involves placing a breathing tube below the larynx or voice box. Once this tube is in place, it allows a patient to remove mucus from the lungs and clear out blockages from the airway. As a result, suction machine perform this work so the patient does not have to try to remove this fluid on their own through coughing. [Source: ehow]

Suction Machine Block Diagram

The diagram above shows the components of a high pressure mobile suction apparatus. The difference in block between the low pressure suction and the high pressure suction machine as shown above is the method of producing the partial negative pressure.

The pump is protected from infected materials which could be drawn from the reservoir jar by a trap or filter. There is A Cut-Off Valve within the reservoir jar which operates when the level of fluid in the jar is sufficiently high enough to raise the float ‘F’ so as to prevent any foreign material being aspirated into the pump.

There are alternative positions for the pressure gauge. A trigger valve is fitted close to the nozzle in order maintain a constant standby vacuum in the reservoir jar. [Source: Anesthetic machine by C.S Ward]

Working Principles of Any Suction Unit/Machine

The suction machine is a means of producing a vacuum wherein air is completely sucked out of the canister or reservoir bottle (producing vacuum or negative pressure) hence sucking effects on any fluid the catheter or tubing come in contact with. The sucked air releases to the outside through a filter so as to prevent environmental pollution by sucked materials.

Care and Maintenance of Medical Suction Machine

Suction machine is essential medical equipment for hospital especially in the operating room (OR), emergency room (ER), intensive care unit (ICU) and some wards. This machine if not properly taken care of will serve as potential source of danger to innocent patient and complicate already worsen situation.

A medical suction machine helps remove fluids –vomit, and other secretions during or after surgery

I have seen in some hospitals where if a patient is conscious and know the kind of suction machine they will use for him/her will reject the use of such machine. This is because of the deplorable state of such machines dirty, rusted and unkempt. Thus a patient stands the risks of infections and cross infections by the use of such machine.

To properly care and maintain your suction machine, you need to pay attention to the following:

  • Cleaning of reservoir jar. The reservoir jar hosts suction fluids
  • Cleaning of catheter and delivery hose
  • Ensure integrity of floating stop valve
  • An in the same way minimize leakage current
Cleaning and Parts Replacement
  • The Reservoir or Suction Canister: you must clean the reservoir jar after use. For example, the direction for cleaning may differ by manufacturers because the canister made of different plastic materials or glass. In case of glass reservoir, you need to take precautions in cleaning because it is breakable and equally expensive
  • The Delivery Tubing: clean the catheter after each use by thorough rinsing with hot water and then by a diluted solution of one part to three parts hot water and air dry
  • The Catheter: catheter could be clean following manufacturers’ prescription but replacement is necessary more often
  • Bacterial filter: you must replace bacterial filter every two months or so depending on the amount of use the machine has or anytime the collection bottle overflows
  • Battery Replacement: for battery-powered, ensure the battery is in good charging condition

Common Faults with Suction Machines

  • Cut-off valve failure
  • Improper seal of the suction bottle
  • Soiled filter and

Similarly,

  • Leaky capacitor
  • Power Switch failure
  • Fuse blown or circuit breaker tripped off and
  • Blocked catheter
Troubleshooting A High Pressure Suction Machine 
  • User did not plug the machine
  • You forget to properly set suction pressure via the control switch/knob and
  • Low or no pressure at regulator port

In the same way,

  • No or low pressure at patient port
  • Low or no pressure at end of suction tubing and
  • The bottle cover is not properly in place or seal is missing.

However, if you tried all but does not solve the problem, you need to check The Suction Head. For your safety, you need to disinfect ‘properly’ a suction machine. And as a result, for instructions on how to disinfect a suction machine, check here.

Typical Suction Heads

Finally, there are different types of design of the suction head as illustrated below.

Check out for these:

  • Electrical Safety Test – Include MP3
  • Sources of Quality Suction Apparatus
  • Keeping Your Suction Machine Safe and Hygienic

How to Disassemble and Reassemble a Suction Machine – Show Video and Snapshot – https://www.youtube.com/watch?v=Wv1M3eMHlnY

 

 

 

 

 

Electrical Testing and Verification

Electrical Safety Best Practices

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The subject of electrical safety for technicians revolves primarily around electrical safety grounding, electrical insulation, and control of humidity. Other factors resulting in general electrical safety are personal protective equipment, proper preventive maintenance procedure and knowledge of electrical safety basics.

Electrical safety best practices

Electrical safety is an important subject for consideration for products that uses electricity. Safety is an important factor before, during and after any electrical work. These electrical works include electrical installation, design and production. Likewise, maintenance, and troubleshooting. Users of electricity too should know what is going on around electrical installations.

Electricity gives power to nearly every appliance we use on daily basis. There were reports of fatal issues related to electricity such as electric shock, fire, burn, and even electrocution and even death. It’s our responsibility as users and handlers to consider safety as primary issues in matters concerning electricity.

Regulatory bodies maintain electrical safety standard:

Worldwide there are government regulations and agencies about safety standards that are mandatory for products to conform with before being accepted to the market. There are safety and standard agencies like ULCE, CSA, BSI, SON, CCC, and so on. Aside the international standard individual countries and region has her regulatory bodies.

Mandatory Safety Tests:

There are series of mandatory safety tests such as “high voltage test’ also referred to as ‘Dielectric Voltage Withstand Test or High Potential Test’. Other mandatory tests are ‘Insulation Resistance Test”, ‘Ground Continuity Test” and ‘Leakage Current Test”/Patient Leakage Current Test. You can find those tests and other tests in IEC/CEI IEC 61010 and many other national and international standards and codes. Electrical safety test is very important to safeguard against electric hazards such as fire, shock, and damages to equipments. Not only those, the worst negligence is death by electrocution.

Recommended Class of Equipment:

There are safety recommendations for different classes of equipment. The classes is for specific locations such as hospital; Gas or Petrol station; flour mills; laboratories and lots more.

Physical Observation:

The best way to remain safe when using electricity is to play safe and be aware of your surrounding. Look up and around to see if there any power line especially when working on roof or tree. Electricity is very dangerous near water. Regular check electrical wiring and equipment is a must to avoid catastrophic damages and what do you look for? You need to search out for loose connections, burn outs, water or fluid dripping on wire/cable or sockets and worn out insulation.

What must you do to ensure electrical safety?
  1. Make provision for electrical safety kits
  2. Before you work on any electrical circuit, total isolate the circuit from the power supply and carry out tests. These tests are to ensure that all poles of the circuit are dead.

Other requirements are:

  1. Regularly check all electrical appliances
  2. Replace broken cable
  3. Maintain proper electrical earthing in socket and plugs
  4. Use Proper insulating materials.
  5. Test all electrical appliances before use
  6. Obey national and international standards and codes