power transformers

Physically, yes.

Seriously, I've never tried it. The problem with putting sensors on transformers is that the changing magnetic field may affect the sensor and/or its signal. A transmitter or temperature display may have a common-mode input or a filter that may reduce the interference enough to get a decent reading but you'll have to find that out from your instrument supplier.

However, I don't see any problem with trying it. 'Should be simple to do just to test it. Other than the standard safety measures of working with electrical equipment, it should be safe to do.

If this is an existing transformer, it will depend on the type of insulation. A cast epoxy resin would not have any openings for inserting any type of sensor. An air-cooled varnish insulated unit, or an oil-cooled unit would allow you to place an RTD or thermocouple directly on the winding insulation.

If you are having temperature concerns, it might be easier to use a non-contact thermometer. These devices use infrared measurement to determine temperature. You could mount one on the enclosure and point it at the windings to get pretty good temperature values. You could also use it to monitor temperature at various locations on the windings to check for hot spots.

Yes, but you must decide carefully what you want to measure. There will generally be a sizeable temperature gradient even for steady state temperature. If you want copper temperature, you'll need to get good contact; I've used spot-welding and thermal epoxies. For large conductors, you may want to drill a hole and insert a thermocouple (as, for example, during fault currrent testing) to get interior short-time temperature.

Depends on the application, what are you trying to do?

We use thermocouples all the time - they work well, but require about 5-30 sec averaging. You can also use the change in resistance of the wires to calculate the Trise of the copper itself.

Most transformers, when properly tested are done so in an insulated box, with zero airflow, running at full load until a stabil temp has been reached for at least 5 minutes.

Hope this helps.

Normally the manufacturer provides the means for monitoring the temp .If u want to place a sensor inside there must something specific.In oil cooled transformers u can place but you won't have any advantage as it it is difficult to locate the hot spot.For normal operations manufacturers provision is sufficient

Which part of Transformer you want to measure temprature ?

nascon