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TEMPERATURE
ELEMENTS Thermocouples / RTD Assemblies.
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Thermocouple
(T / C)
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Resistance
Temperature Detector (RTD)
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- It
employes two dissimilar metals
- When two such dissimilar
metals welded together at one end and subjected to
heat, it develops a small DC voltage (EMF), corresponding
to temperature difference between hot junction (measuring
junction) and cold junction (reference junction).
- The temperature - EMF
characteristics have an established pattern for different
type of hermocouple elements like,
T, J, K, N, E, R, S, etc.
- Temperature - EMF characteristics
conform to
ANSI MC 96.1 / IEC 584 / DIN 43710 standards.
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- It employs high purity
electrical resistance wire, non inductively wound
on ceramic or glass base.
- When RTD element is subjected
to heat, it changes its electrical resistance value,
corresponding to variation in temperature and its
thermal coefficient () (Alpha).
- The temperature resistance
characteristics have an established pattern for different
resistance elements, like Copper, Nickel, Platinum
etc.
- Most commonly used resistance
element is Platinum known as Pt 100 (100 ohms at 0°C).
- Temperature resistance
characteristics conform to DIN 43760 / IEC 751 / BSS
1904 / JIS C1604 standards.
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- Conventional thermocouple
or RTD elements pass through multi bore insulators,
encased in outer protection sheath and connected to
temperature measuring instrument.
- Mineral insulated (MI)
sensors are insulated with tightly compacted high
purity magnesium oxide powder, simplex or duplex,
enclosed in various metal sheaths and connected to
temperature measuring intrument.
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ENCLOSURE
- Staninless
Steel, Die Cast Aluminium with cable entry.
- Protection
: IP, Flame Proof Gr IIA, IIB or IIC, Increased
Safety.
- Termination
: Brass/SS connectors with markings for polarity,
colour codes and type of Thermocouples.
Spring Loaded Terminal Block - if required.
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