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How to choose a Temperature Switch

A temperature switch is a switch  that is responsive 


to temperature changes. Temperature switchesgenerally are provided with a temperature responsive element which will open or close a switch when a predetermined minimum pressure or temperature is sensed by the responsive element. For protection against thermal overload,semiconductor switches are provided with integrated temperature sensors. The temperature sensors acquire the temperature of the power switch and convert this into a temperature-dependent, analog signal which then can be interpreted in a circuit. Temperature sensitive switches, such as a thermostat, typically comprise a temperature sensor which is used to open or close electrical contacts at specified temperatures. A bimetal strip of dissimilar metals is used as the sensing element for temperature sensitive switches. Temperature sensitive switches are often used for thermal protection purposes. If a device gets too hot, the temperature sensitive switch opens the electrical circuit, thereby eliminating power to the circuit. For example, temperature responsive tip-switches are particularly useful in connection with electric heaters.

Tips for choosing the right temperature switch

A temperature switch responds immediately to temperature change. A temperature switch will usually have some sort of component that responds by opening and closing a switch once the established minimum pressure or temperature is recognized by the responding component.

A thermostat is one example of a temperature switch. It is usually includes a temperature sensor. The sensor opens and closes electrical contacts once a present temperature is reached.

Which temperature switch is right for your application?

Temperature sensitive switches are commonly used as a form of thermal protection. If an appliance becomes too hot, the temperature switch will open the electrical circuit. This will immediately shut off power to the circuit.

Trying to find the right temperature sensor to use in a system can be difficult. If you do not do your research, you could spend a lot of money searching for the right one. It is estimated that 55 percent of all electronic system failures are the result of a temperature related cause.

Programming the switch

A thermal device can be programmed to activate at several different temperature thresholds. The temperature switch monitors the temperature of an electrical appliance and maintains control over the amount of power that is used. If the temperature is programmed to low it will reduce the appliance's performance and efficiency. It will also create an environment for condensation to develop. This can lead to insulation breakdown and corrosion.

Maintaining the temperature threshold

The sensor sends out a signaling current that matches the absolute temperature. The rating, or value, of the electrical current determines what the temperature threshold of the temperature switch should be. The typical temperature switch design is complicated and can consume a lot of power. There is a new product called a sub threshold CMOS temperature switch available. Its function is simpler, and it uses less power. However, it is not as stable as the more common temperature switch found in most electrical devices when it comes to maintaining threshold temperature.

The functions of thermal protection

The temperature switch handles two main situations: over temperature protection and temperature control. Over temperature protection reduces the incidence of abnormally high temperatures. Its job is to isolate the switch before temperatures exceed the critical safety point. Temperature control refers to cycling around the heat and fan temperatures that switch these devices on and off.

The CMOS temperature switch has a basic temperature switch circuit. The switch's operation depends on the chip temperature which can change very suddenly whenever the temperature reaches a dangerous range. This is also known as the threshold program which is a programmed function.

Choose the best thermal device for the job

Each temperature switch is built to complement a specific application. At face value you may notice the variation in many applications and assume that one temperature switch is better than another. But this is not the case. Each thermal device is designed for a purpose and should be able to meet a wide range of criteria.

It is important to compare and contrast the varying technology that creates these devices. The simple design and engineering that allows them to operate independently is a big reason for why a temperature switch is such a necessary device.

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Our PRODUCTS for COAL MINES

ELECTRICALS

FLP/WP  well Glass
FLP/WP Tube Light Fittings
FLP/WP  Lighting (CFL)
FLP/WP Head and Tail Lamp
FLP/WP Miners Cap Lamp

FLP/WP Audio Visual system for mobile equipment

INSTRUMENTATION and ELECTRONICS

FLP/WP Limit Switch
FLP/WP Float Switch
FLP/WP Level Switch

FLP/WP Gas detection Kit

FLP/WP Temperature Switch

FLP/WP Push Button Station

FLP/WP R/S

Float Switch

The Series 100 is equipped with flanged hambers to simplify system checks or scheduled maintenance. It is available with a variety of mounting configurations such as side/side, side/bottom, side/side/bottom drain.

APPLICATION

For Liquid Level Alarm or Liquid Level Control

SPECIFICATION

Mounting External Chamber on Side
of Tank (vertical)

Sp. Gravity 0.7 and above

Pressure/Temp. Rating 40 Bar at 40 Deg. C or 18
Bar at 400 Deg. C, others
on request

Process Connection Flanged, Socket Weld or
Screwed

Connection Typel Side/Side or Side/Bottom

Chamber Material CS, SS 304/316, other
materials on request

Float Material SS 316, other materials
on request

Switch Housing Die Cast Aluminum (LM6)

Type of Micro Switch

1SPDT, 2SPDT(Equal to 1DPDT) with Silver or Gold
Plated Contact
Hermetically Sealed Switches for Highly Corrosive or Highly Explosive Area

Enclosure Protection

Ex id Telephone

ADVANCED EEC Telephone

Salient Features I
~ SS304 Key pad, magnetic receiver lock

~ Loud Ringer sound

~ Used in wide Hazardous Locations in Chemical, Petrochemical industries, Refineries, COAL and OIL mines, etc.

SAFETY Alert

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Electric shock from a light fitting

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• MIRMgate

What

A mineworker received an electric shock when his forearm made contact with a flameproof Burn Brite fluorescent light fitting (Certificate No AUS EX 424X) on a continuous miner in the hazardous zone of a coal mine. The victim was transported to hospital in accordance with the mines electric shock protocol and was allowed to leave after medical tests and examination determined that no permanent injury had occurred...

Why

The three factors of: 1. A failure of the ingress protection ; 2. Unearthed external metal on the Burn Brite light fitting, and ; 3. The 500 mA/250 ms setting of the earth leakage protection, combined to present two separate hazards in the hazardous zone of the coal mine. These hazards were; 1. A touch voltage was able to deliver an electric shock to a mineworker,; AND 2. The explosion-protected equipment failed to contain the electrical energy within the enclosure under fault conditions creating a potential source of ignition of methane

Recommendations

The issues raised herein may also apply to other light fittings and on other machinery at NSW mines. ; Manufacturers of light fittings and continuous miners, should review the risks to safety from their products and to promptly stipulate earthing, protection, maintenance and inspection requirements to their customers as required by the NSW OHS Act...

Subjects

Tasks

Hazards

Energies

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