Although conventional loss of field (LOF) protection schemes, especially impedance-based ones, are widely used for large-scale synchronous generators, they may not provide proper performance for small-scale synchronous generators (SSSGs) due to various concerns including, (i) large tripping time for unrecoverable LOF (ULOF) which may lead to severe voltage drop and stalling of nearby induction motors, (ii) LOF function maloperation during islanding events, and (iii) LOF function maloperation during recoverable LOF events. To resolve these issues, a new adaptive LOF protection logic is proposed for SSSGs. After ULOF events, the automatic voltage regulator (AVR) output gradually increases, while the SSSG internal voltage does not considerably increase. Based on this principle, some measurable or easily calculable parameters, including AVR output and SSSG internal voltage, are adopted to discriminate ULOF from other disturbances. Meanwhile, the proposed logic is wisely equipped with an adaptive time delay to prevent stalling of nearby induction motors and enhance operation speed during ULOF. Performance of the proposed algorithm is evaluated under various LOF and islanding events as well as short circuits. Obtained promising results confirm desirable performance of the proposed approach. Besides, compared to the impedance-based method, the proposed adaptive time delay considerably improves the security and reliability.