passive infrared sensor

 passive infrared sensor (PIR)


A passive infrared sensor (PIR sensor) is an electronic sensor that measures infrared (IR) light radiating from objects in its field of view. They are most often used in PIR-based motion detectors. PIR sensors are commonly used in security alarms and automatic lighting applications.

PIR sensors detect general movement, but do not give information on who or what moved. For that purpose, an imaging IR sensor is required.

PIR sensors are commonly called simply "PIR", or sometimes "PID", for "passive infrared detector". The term passive refers to the fact that PIR devices do not radiate energy for detection purposes. They work entirely by detecting infrared radiation (radiant heat) emitted by or reflected from objects. 
Operating principles

All objects with a temperature above absolute zero emit heat energy in the form of radiation. Usually this radiation isn't visible to the human eye because it radiates at infrared wavelengths, but it can be detected by electronic devices designed for such a purpose.

PIR-based motion detector
A PIR motion detector used to control an outdoor, automatic light.
An indoor light switch equipped with PIR-based occupancy sensor

A PIR-based motion detector is used to sense movement of people, animals, or other objects. They are commonly used in burglar alarms and automatically-activated lighting systems.


A PIR sensor can detect changes in the amount of infrared radiation impinging upon it, which varies depending on the temperature and surface characteristics of the objects in front of the sensor.When an object, such as a person, passes in front of the background, such as a wall, the temperature at that point in the sensor's field of view will rise from room temperature to body temperature, and then back again. The sensor converts the resulting change in the incoming infrared radiation into a change in the output voltage, and this triggers the detection. Objects of similar temperature but different surface characteristics may also have a different infrared emission pattern, and thus moving them with respect to the background may trigger the detector as well.

PIRs come in many configurations for a wide variety of applications. The most common models have numerous Fresnel lenses or mirror segments, an effective range of about 10 meters (30 feet), and a field of view less than 180. Models with wider fields of view, including 360°, are available, typically designed to mount on a ceiling. Some larger PIRs are made with single segment mirrors and can sense changes in infrared energy over 30 meters (100 feet) from the PIR. There are also PIRs designed with reversible orientation mirrors which allow either broad coverage (110° wide) or very narrow "curtain" coverage, or with individually selectable segments to "shape" the coverage.

Differential detection

Pairs of sensor elements may be wired as opposite inputs to a differential amplifier. In such a configuration, the PIR measurements cancel each other so that the average temperature of the field of view is removed from the electrical signal; an increase of IR energy across the entire sensor is self-cancelling and will not trigger the device. This allows the device to resist false indications of change in the event of being exposed to brief flashes of light or field-wide illumination. (Continuous high energy exposure may still be able to saturate the sensor materials and render the sensor unable to register further information.) At the same time, this differential arrangement minimizes common-mode interference, allowing the device to resist triggering due to nearby electric fields. However, a differential pair of sensors cannot measure temperature in this configuration, and therefore is only useful for motion detection. 

what is High Voltage Switchyards

High Voltage Switchyards

The function of the electric power delivery system is to transport electric power from generation sources to end users. Switchyards and substations are important components of this system.

A switching substation, or switchyard, is a substation without transformers that operates only at a single voltage level. Switchyards, used mainly for connections and interconnections, are essential for transmission, distribution, collection, and controlling the flow of electricity. The switchyard delivers power generated at the power plant to the electrical grid. Switchyards are generally classified by voltage level, circuit breaker and bus arrangements. Switchyards are often located directly adjacent to or near a power station.

Control Panel vs MCC

What Is The Difference Between Control Panel And MCC?

Do you know what the difference between the control panel and MCC is?

Do you know how they actually work and help you till what extent? Do you know which one if the right choice for your workplace? No, so the answer to all your questions is right here. A control generally consists of a controller which helps to give digital signals to the MCC panel to start the motor. These are specially designed to protect electrical equipment from heavy fluctuations in loads. These include PLC, VFD, fuses, switches; transformers and many other necessary components which are must to control the voltage of current for the smooth and hassle free performance of your device.

On the other hand, MCC stands for a motor control panel, which consists of feeder for motor and blower. These are specially designed according to the different motor rating and it can be available in automatic or manual operation provisional. If you opt for an auto provisional then control panel is a must to fulfill its function because the only control panel gives a signal to it so that it start the motor and power supply to the equipment on a constant basis. In simple words, you can say both are incomplete without each other. Because the function of one is totally depends on the function of other. If you want to buy it so always go to trusted power control panel manufacturers.

This is because a trusted electrical panel manufacturers company will never compromise on the quality and pass the products on different quality parameters which help to ensure its hassle free performance, durability, longer life, low maintenance, and high- efficiency and low power consumption. And at the present time, a single panel is used for both control panel and MCC rather than using the separate panels. These are highly demanded in the globalized market because of its high-performance and low price.

Motor star delta changeover time delay

How to set timer in Star - Delta starting circuit

There are two very basic ways of determining the correct point at which the control gear should change the winding configuration from 'star' (starting mode) to 'delta' (running mode). Both methods determine the point at which the rotor has achieved it's maximum speed in star, and therefore the point at which the starter should change to delta.

One is by current measurement: Firstly, set the delta timer to it's maximum setting. Put a clip on (tongue tester) ammeter on one of the lines FEEDING the starter. Set a stopwatch going when you press the start button. Watch the ammeter - it will peak immediately on start up, then the current will drop off as the load accelerates. As soon as the current steadies off, stop the watch. At this point (approximately 85% full load speed) the motor can achieve nothing more by remaining in star, and this is the latest point in time that delta changeover should be made.

The other simple way to determine optimum change over time is to use a tachometer on the motor shaft (mechanical or optical). Again, use a stop watch. Observe the Tacho. Acceleration characteristics will vary dependent on the driven load, but the speed will settle out (again at approx. 85% full load speed. Stop the watch at this point. Set the timer to the time recorded on the stop watch.

In star Delta usually we consider that the load and motor torque are equal when the motor reach 75-85% of the speed. At this time you stop the star connection to go with delta connection, the time is around 30 to 50 milliseconds, to avoid short-circuit. But when the motor is connected in delta, at start you've got a temporary current peak due to back electromotive force.

So to avoid this you have different option, by these, you can delay of 1 or 2 seconds the time between star and delta, but it depend on inertia of the load, another solution is to put a resistor in series with the delta connection for 3 seconds to limit the current peak, another is to put the resistor directly in series with the motor at star disconnection.

These methods determine the LONGEST period a motor can be left in 'star'. High inertia loads should be allowed to reach this point.

Different applications i.e fan motors or centrifugal pump motors which run up to speed with closed dampers or valves can be switched into 'delta' much earlier, as the only load being accelerated is the physical mass of the impeller or blade.

waht is rope access service

Rope access service

Rope access or industrial climbing is a form of work positioning, initially developed from techniques used in climbing and caving, which applies practical ropework to allow workers to access difficult-to-reach locations without the use of scaffolding, cradles or an aerial work platform. Rope access technicians descend, ascend, and traverse ropes for access and work while suspended by their harness. Sometimes a work seat may be used. The support of the rope is intended to eliminate the likelihood of a fall altogether, but a back-up fall arrest system is used in case of the unlikely failure of the primary means of support. This redundancy system is usually achieved by using two ropes - a working line and a safety line.

Trade associations such as IRATA have mandatory policies where member companies must submit all accident, incident and near miss occurrences to permit evaluation and comparison of information from an entire industry. This highlights any trends in incidents and assists in the evolution of equipment and procedures allowing continuing improvement to work practices. The above techniques along with the trade association’s organic approach has meant very few accidents since the beginning of this activity around the 1980s

การเข้าถึงเชือกหรือการปีนป่ายเพื่อทางอุตสาหกรรมเป็นอีกหนึ่งรูปแบบของการกำหนดตำแหน่งงาน ซึ่งเริ่มแรกพัฒนาจากเทคนิคที่ใช้ในการปีนเขาและถ้ำซึ่งใช้ rope work ที่ใช้งานได้จริงเพื่อให้คนงานเข้าถึงสถานที่ที่เข้าถึงได้ยากโดยไม่ต้องใช้นั่งร้าน

ช่างเทคนิคเกี่ยวกับการเข้าถึงเชือกลงมาขึ้นและไต่เชือกเพื่อการเข้าถึงและการทำงานในขณะที่ถูกระงับโดยสายรัด บางครั้งอาจใช้ที่นั่งทำงาน การสนับสนุนของเชือกมีวัตถุประสงค์เพื่อกำจัดโอกาสของการล้มโดยสิ้นเชิง แต่มีการใช้ระบบสำรองเพื่อป้องกันการตกในกรณีที่ความล้มเหลวที่ไม่น่าเป็นไปได้ของวิธีการสนับสนุนหลัก ระบบความซ้ำซ้อนนี้มักจะประสบความสำเร็จโดยใช้สองเชือก - สายการทำงานและสายความปลอดภัย

สมาคมการค้าเช่น IRATA มีนโยบายบังคับซึ่ง บริษัท สมาชิกจะต้องส่งอุบัติเหตุเหตุการณ์และเหตุการณ์ที่เกิดขึ้นใกล้พลาดทั้งหมดเพื่ออนุญาตให้มีการประเมินและเปรียบเทียบข้อมูลจากทั้งอุตสาหกรรม สิ่งนี้ชี้ให้เห็นถึงแนวโน้มของเหตุการณ์และช่วยในการวิวัฒนาการของอุปกรณ์และขั้นตอนการอนุญาตให้มีการปรับปรุงการปฏิบัติงานอย่างต่อเนื่อง เทคนิคข้างต้นพร้อมกับวิธีการแบบออร์แกนิกของสมาคมการค้าทำให้เกิดอุบัติเหตุเพียงเล็กน้อยตั้งแต่เริ่มกิจกรรมนี้ในช่วงทศวรรษ 1980