Motor MDFP adalah komponen utama pada PLTU karena sebagai supply air ke drum sebagai bahan baku utama untuk proses pembentukan uap. Motor MDFP terpasang pengaman, salah satu nya Relay Differential. Pada Motor MDFP 2A gangguan yang menyebabkan Relay Differential bekerja pernah terjadi pada bulan September 2021, sehingga menyebabkan motor MDFP2A trip dan pengisian air ke drum terkendala. Untuk mengatasi masalah pada Motor MDFP 2A perlu dilakukan pengecekan pada motor dan proteksi motor lebih mendalam. Tujuan penelitian ini menganalisa gangguan Relay Differential bekerja pada motor MDFP 2A. Metode peneltian ini meliputi melakukan pengumpulan Studi Literature, kemudian melakukan pengambilan data mulai dari SLD, Spesifikasi, data gangguan. Kemudian melakukan pengecekan pada Motor MDFP 2A, Breaker, CT, dan wiring. Selanjutnya melakukan simulasi pengujian Relay Differential menggunakan Tools SMRT 46 D dan melakukan perbandingan perhitungan berdasarkan data gangguan dan pengujian dilapangan. Hasil perhitungan berdasarkan data gangguan didapatkan proteksi differential QB yang bekerja, dimana Fasa R nilai dari arus titik bintang motor kurang dari 6A. Sedangkan untuk fasa S dan T lebih dari 6A. Selanjutnya hasil percobaan 2 kali simulasi menggunakan Tool SMRT46D, dimana didapatkan pada pengujian pertama Relay Differential bekerja dan pengujian kedua tidak bekerja sesuai setting yang terpasang. Dari hasil percobaan simulasi, dan data pengujian dilapangan dinyatakan dalam kondisi baik. Proteksi Differential Quick Break bekerja karena terbalik nya polarity kabel power supply pada motor.

The MDFP motor is the main component in the steam power plant because it supplies water to the drum as the main raw material for the steam formation process. MDFP motors are equipped with security, one of which is Relay Differential. In the MDFP 2A Motor, a disturbance that caused the Differential Relay to work occurred in September 2021, causing the MDFP2A motor to trip and filling the drum with water. To solve problems with the MDFP 2A Motor, it is necessary to check the motor and motor protection more deeply. The purpose of this study is to analyze the interference of the Differential Relay working on the MDFP 2A motor. This research method includes collecting Literature Studies, then collecting data starting from SLD, Specifications, disturbance data. Then check the MDFP 2A Motor, Breaker, CT, and wiring. Next, perform a Differential Relay test simulation using SMRT 46 D Tools and compare calculations based on fault data and field tests. The calculation results based on the fault data obtained that the QB differential protection works, where the R phase value of the motor star point current is less than 6A. As for the S and T phases more than 6A. Furthermore, the results of the experiment 2 times were simulated using the SMRT46D Tool, which was obtained in the first test the Differential Relay worked and the second test did not work according to the installed settings. From the results of simulation experiments, and field test data stated in good condition. Differential Quick Break protection works because the polarity of the power supply cable is reversed on the motor.