In my experience with electromechanical relays, I have found that contact resistance is a very important electrical characteristic.
The resistance between the contact terminals determines the relay’s ability to carry current. And the contact resistance is subject to change during the life of the relay. Based on lab investigations and testing, abnormal contact resistance has often been found with the following conditions:
- Overload condition on the contact causing welding
- Contacts reach end of life
- Foreign substance adheres to one of the contact surfaces
- Using a power supply that can output voltage and current, set its maximum voltage output to 6 Volts and the maximum current output to 1 Ampere.
- Connect the leads of the DVM to the common (COM) contact and the normally closed (N.C.) contact terminals.
- Set the DVM to measure Voltage
- Turn on the coil power supply to energize the coil and engage the contacts.
- The reading on the DVM is the Voltage Drop across the contacts. However, since the load is 1A and Ohm’s Law says that V = IR, then V = R. Therefore the voltage reading on the DVM is also the resistance between the contacts.
- Example: If the DVM reading is 15 mV, then the resistance measurement is 15 mOhms.
This simple method of measuring contact resistance can turn out to be very helpful when performing a simple diagnostic investigation.
This video explains the features and benefits of Panasonic’s GF1 Accelerometer. The GF1 is perfect for solar tracking applications and 4×4 anti-lock braking systems, as well as forklifts and scissor lifts.
Learn more about this product by visiting the Panasonic website or leave a comment below and we can get back to you with more information.
This application shows how to connect a Panasonic FPX PLC with a personal computer using Ethernet and TCP/IP internet protocol. The PLC will be sending a string (set of characters) to the PC. Here we find the PLC communication configuration and program, and basic set up of Windows HyperTerminal.
Configuration COM5
The PLC uses a communication cassette AFPX-COM5, this device is set up using a Panasonic program called Configurator WD.
The figure above shows PLC_1, the tag for a FPX-COM5 cassette, set as server. Its current configuration is:
PC Client/Server –HYPERTERMINAL WINSOCK-
PLC program – MASTER or Client side
The PLC program includes conversion from INTEGER data type to STRING data type. Also, you can see how to set up F159; this function is used to send the string from one of the PLC communication ports. This program will send to HyperTerminal a specific value from the PLC memory.
Above you can see how the program converts a variable from integer data type to string data type. As a string the value is linked with other strings constants. This resulting string is saved in a INT ARRAY that works as a buffer. This buffer will be address by a serial communication instruction and later it will be broadcasted over Ethernet. You may notice how the special ASCII characters ASCII are implemented {ASCII: $20 –> SPACE}. It is easy to follow how with the INT ARAY -TxBuffer- populated, the program use it as a transmission table.
The sample program running:
This program will send to HyperTerminal a specific value from the PLC memory. The main idea is to take the value from the PLC memory and convert this value into a string.
As a string the vaile is linked with a message (ResoValue). This new string is placed in a INT ARRAY.
Please review this conversion, remember that the program looks specific PLC address the from there takes the valie and this value is MOVE using a BLOCK MOVE into the INT ARRAY.
In this program we CONCAT two variables in a string (Value and Value2)
PC Server/Client:
The figure above shows how the user will receive that string in its PC, using window HyperTerminal.
Please leave a comment if you have a question, or a suggestion for the next PLC article.
REACH stands for Registration, Evaluation, Authorization and restriction of CHemicals. A global increase of rare illnesses has caused the world to be more cautious of products used in the home and work place. With this awareness, agencies have been set up to monitor and control the substances that are used in manufacturing, as well as impose fines on companies that violate the laws.
In the electronic component industry there are two key agencies, RoHS (Restriction of Hazardous substances) and REACH, which was created to cover substances that were not covered by the six substances of the RoHS Directive. More specifically, REACH deals with the restriction of chemicals that are released into the environment that may cause harm to the human body and animals in the future. REACH regulations were put in place on June 1st, 2007, have expanded to cover 46 substances and the list continues to grow.
Manufacturers’ Obligations:
Companies that manufacture or import one (1) tonne or more of a chemical substance annually will be required to register it in a central database at the European Chemicals Agency (ECHA).
The Registration procedure involves submitting a technical dossier containing information on the substance and guidance on how to handle it safely.
Evaluation allows regulatory authorities to determine if further testing is needed and to assess whether information provided by industry complies with the requirements (dossier evaluation).
Substances of very high concern are subject to an Authorization procedure. Companies who apply for authorization need to show that the risks posed by those substances are adequately controlled. The aim is to give industry the incentive to progressively substitute these substances with safer materials.
Substances of Very High Concern include the following:
- Carcinogens, mutagens or toxic to the reproductive system, categories 1 and 2
- Substances which are persistent, bio-accumulative and toxic
- Very persistent and very bio-accumulative
- Or of equivalent concern
Restrictions are the safety net of the system. Any substance on its own, in a preparation or in an article may be subject to Community-wide restrictions if its use poses unacceptable risks to health or the environment.
Substances in articles which are on the “candidate list of substances of very high concern” will need to be reported to the European Chemicals Agency starting June 1, 2011.
Exempted Substances
Some chemicals that have been exempted and excluded from registration include:
- Water
- Oxygen
- Noble gases and cellulose pulp
- Substances naturally occurring such as minerals, ores and ore concentrate as long as they are not chemically modified.
- Substances in food and medicinal products as they are covered by other specific legislation
- Waste
- Substances used for defense purposes
Intermediates: Chemical substances used to manufacture other chemical substances are called intermediates. If manufactured and used inside a closed system they are generally exempt from REACH (non-isolated intermediates).
Products such as construction material, electronic components, toys or vehicles are covered by REACH if they contain substances intentionally released. These substances need to be registered.
Benefits of the new REACH Regulation
The primary benefit of REACH is that it systematically identifies the hazards and risks of chemicals. This allows companies to identify and communicate appropriate risk management measures through the supply chain.
Better knowledge of chemicals and more efficient communication on risk management measures will contribute to the prevention of health problems caused by exposure to chemicals. This is expected to lead to a lower occurrence of occupational diseases and preventable deaths, thus lowering costs to national health systems. The benefits will come gradually as more and more substances are assessed under REACH.
More details can be found at the European Commission’s website.
If you have any questions on Panasonic’s electronic components, or generally about REACH, please use the comments section.
This video demonstrates the A5 Servo’s Notch filter function which is useful for vibration suppression by eliminating harmonic frequencies.
Learn more about the A5 Servo on Panasonic’s site: http://pewa.panasonic.com/automation-controls/servos-and-drives/a5/
