Which Chemical Powder is Used Inside rtd Sensor?

None that I know of. Resistance temperature detectors or resistive thermal devices (RTDs) are usually made of fine platinum wires or traces.

Thanx a lot about the info.

But i think i felt a little short in explaining what i mean.

I mean there is some kind of white coloured chemical powder used inside the RTD(Resistance Temperature Detector) sheath (which i've seen while making a RTD somewhere) but forgot the name.

I need to know the name of the powder & its purpose.

Thanx in advance.

Whatever it is it will be electrically and thermally inert, so it's nothing to worry about.

Call it "filler", perhaps.

I image you mean this type of sensor:

This was taken from the RdF website. They mention "insulating powder", but not what it is. I'd think it's probably silicon dioxide (SiO₂) or similar.

You can make google search for antioxidant for heaters,I guess thats what you are looking for,

Yes thats GA, But I have one doubt that if it is used for insulation? and reason for that is I have seen same material in the cartage fuses where single strand wire is tied between two terminals, and there is nothing from wire to be insulated. I am not very sure but if this powder is not used for absorbing heat or to reduce the slow oxidation of wire?

Don't think either heat absorption or oxidation are issues with a Pt RTD. The powder is to allow the wire to move (expand and contract) while supporting it and stopping it rattling about.

>But I have one doubt that if it is used for insulation? and reason for that is I have seen same material in the cartage fuses where single strand wire is tied between two terminals, and there is nothing from wire to be insulated. I am not very sure but if this powder is not used for absorbing heat or to reduce the slow oxidation of wire?

The RTD element needs to be electrically insulated from the sheath because a DC current is pumped through the RTD element. If the RTD element were to contact the sheath, an alternative current path could form, radically distorting the measurement. Due to electrical insulation, RTD's are not subject to the difficulties of ground loops so common with grounded thermocouples.

Ideally the powder would very thermally conductive to minimize thermal lag, the time lag for heat transfer through the sheath and insulation to the RTD element. But MgO and the other insulation powders all have some thermal resistance that just has to be accepted.

Insulation does not absorb heat, it only delays heat transfer. Even if there were a heat absorbing material, it would not be used because such would prevent the RTD element from sensing the temperature change due to heat transfer.

JohnDG is correct that the insulating powder supports the connecting wires and the RTD element which is wound around the mandrel inside the sheath.