Hi,
You don't give relay coil current.
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* bjt continous current rating should be larger than relay current
* bjt power dissipation should be low, i recommend a temperature rise smaller than 20K
* diode peak current rating should be larger than relay current
R2 is useless.
I see no problem in your circuit.
Some hints for improvements. Not necessary, but maybe you find it usefull:
* use a relay with NC contacts to save power
* you could use a "digital bjt" with resistor inside to reduce part count
* or you could use a small mosfet to reduce transistor power dissipation. (Not overall power dissipation)
To reduce power with your configuration (2s OFF):
* switch the relay ON with 1s and 100% duty cycle, then reduce duty cycle to 50% (check datasheet).
This reduces power dissipation and heating of the relay coil.
No need for high frequency. Everything above some 100Hz is OK.
Klaus