Development of Short-Circuit Protection in Hands-On Electronic Training Set for Vocational Education ^†

Hands-on activities are one of the characteristics of vocational learning. Learners will be triggered to activate their cognitive and psychomotor aspects with hands-on activities. These activities involve training sets to support students in understanding some specific vocational topics. The level of student understanding can be classified as the mastery of vocational-specific skills. Learners with minimum vocational skills can be grouped as beginners. However, beginner learning in vocational training is a considerable risk, and training sets have a high potential for damage. Electronic training sets are especially prone to voltage installation errors, resulting in fatal damage. Therefore, this study developed a relay-based short-circuit protection for the electronic training set. The development process consists of identification, designing, circuit processing, and circuit testing. This circuit was equipped with relay protection, a buzzer, and an LED short indicator. Drop-voltage was utilized during the short-circuit to activate relay protection. A Zener diode (3V3 and 5V6) was employed as a drop-voltage sensor and Op-Amp comparator. The test results reveal the circuit’s functionality to protect against short-circuits on 5 V and 12 V direct currents. The operating principle is that before the voltage hits zero (0), the relay will cut off the voltage line between the training circuit and the power supply. This reduces the risk of damage due to faulty circuits or misconnections.