  LT Del is a yellow symbiotic system that consists of a bright K3-type giant
and a hot subdwarf with a temperature of about 10$^5$ K. We present the results
of our spectroscopic observations of LT Del over the period 2010-2018. In 2017
the star experienced a second low-amplitude ($\Delta V\sim0.^{m}7$) outburst in
the history of its studies. The emission spectrum of the star represented in
the optical range by hydrogen, neutral and ionized helium lines underwent
significant changes in the outburst. The fluxes in the HI and HeI emission
lines increased by a factor of 5-6, the HeII $\lambda$4686 line grew by a
factor of 10. According to our estimates, in the 2017 outburst, the temperature
of the exciting star rose to $T_{\text{hot}}\sim$130~000 K, while during the
first 1994 outburst the change in temperature was insignificant. This suggests
cool and hot outbursts of LT Del by analogy with similar events of another
yellow symbiotic star, AG Dra.
