Relai differensial di PLTU Lontar extension merupakan relai baru yang belum pernah di operasikan dikarenakan pembangkit masih dalam tahap pengujian. melakukan penyetelan dan Pengujian Relai differensial dilakukan dengan memastikan semua fungsi proteksi yang ada pada relai telah sesuai dengan standar SPLN. Fungsi yang ada pada relai differensial yaitu Fungsi proteksi differensial arus, Fungsi proteksi over current, fungsi proteksi ground fault, fungsi proteksi over exitasi, fungsi proteksi over voltage dan fungsi proteksi thermal overload. Penyetelan nilai setting menggunakan software siemens Siprotect 5 dengan Data setting yang dikeluarkan oleh PLN Pusat Enjiniring Ketenaga listrikan atau PLN PUSENLIS dengan Nomor dokumen 10098-E-59-BAT-0011-01-1 Pengujian dilakukan dengan metode analisi deskriptive. Sesuai dengan setting yang telah diberikan maka hasil pengujian proteksi differensial arus relai akan bekerja disaat Idiff 0.43 dengan waktu delay 34ms, pengujian Overcurrent didapatkan hasil rasio pick up dan drop off sebesar 0.95 dan waktu trip mendapatkan error maksimal 1.039%, Hasil pengujian neutral over voltage ditemukan bahwa relai trip pada saat tegangan disisi neutral terbaca 11.56 V dengan waktu trip 3.041 s, hasil pengujian over exitasi didapatkan bahwa relai trip pada 1.3991 V/F dengan waktu trip 1.091. hasil ngujian proteksi thermal overload ditemukan bahwa disaat arus sebesar 2 kali dari arus setting 0.572 A maka waktu trip pada relai 898.7 s.

The differential relay at the Lontar extension power plant is a new relay that has never been operated because the plant is still in the testing stage. Differential Relay Adjustment and Testing is carried out by ensuring that all protection functions on the relay are in accordance with SPLN standards. The functions that exist in differential relays are current differential protection function, over current protection function, ground fault protection function, over exit protection function, over voltage protection function and thermal overload protection function. Setting value adjustment using Siemens Siprotect 5 software with setting data issued by PLN Pusat Electrician Engineering or PLN PUSENLIS with document number 10098-E-59-BAT-0011-01-1 Testing was carried out with method analysis descriptive. In accordance with the settings that have been given, the results of the relay current differential protection test will work at I diff 0.43 with a delay time of 34ms, the Overcurrent test obtained the result of a pick-up and drop off ratio of 0.95 and a trip time of 1.039% with a maximum error, The results of the neutral over voltage test found that the trip relay at the voltage on the neutral side read 11.56 V with a trip time of 3,041 s, the results of the over exit test were obtained that the relay trip at 1.3991 V/F with a trip time of 1,091. The results of the thermal overload protection test found that when the current is 2 times the setting current of 0.572 A, the trip time at the relay is 898.7 s.