In the fields of diesel generator sets, marine power systems, and emergency power sources, the DEIF Multi line 2 series controllers (including GPU generator protection units, GPC generator parallel controllers, and PPU power station parallel units) are renowned for their high integration, flexible scalability, and reliable performance. For on-site engineers, correct mechanical installation, electrical wiring, and parameter configuration are key to ensuring safe grid connection and stable operation of the unit. This article is based on the Multi line 2 installation manual (version 2.40.0 and above), which systematically outlines the technical points of the entire process from unboxing to power on debugging, and provides practical suggestions combined with common engineering pain points to help engineers quickly complete project delivery.
Overview of Product Positioning and Selection
Multi line 2 is a microprocessor control platform designed by DEIF specifically for medium to large generator sets, integrating three-phase true RMS measurement, LCD human-machine interface, multiple protection functions, and rich expandable I/O. The three major models correspond to their respective core applications:
GPU (Generator Protection Unit): Focusing on single machine protection, it has ANSI protection such as reverse power (32) and overcurrent (51 two-stage), built-in event recording (150) and GSM SMS alarm, and can be independently used as the main protection of the power station.
GPC (Generator Parallel Controller): Based on GPU, it adds synchronization, active/reactive power allocation, fixed frequency/power, and droop control, supporting parallel connection with multiple units or the power grid.
PPU (Power Plant Parallel Unit): Similar in function to GPC, but focusing on power management of multiple power stations, it can achieve load dependent start stop control.
In terms of hardware, the three share the same chassis structure and card slot system, and optional modules (such as voltage/reactive power regulation, analog output, engine communication) are interchangeable, greatly simplifying spare parts management.
Mechanical installation: panel opening and fixing method
The controller body adopts IP20 protection level, and the display unit can reach IP54 (front panel) through optional sealing gasket. There are two standard installation methods:
DIN rail installation: suitable for non vibration environments, fast and convenient.
Base screw fixation (recommended): There are 6 screw holes on the back of the chassis, requiring 6 M4 screws to be tightened. In situations where vibration is required, such as ships, base screws must be used for fixation to withstand 10g impact and 2g vibration.
The panel opening size strictly follows page 76 of the manual: display unit opening H × W=10mm × 30mm, display module shape 115mm × 220mm. It is recommended to use laser cutting to ensure accuracy. When installing, pay attention to the display cable (option J1/J2) length not exceeding 6 meters, and use Belden 9540 or equivalent shielding wire to avoid signal attenuation.
Hardware board slot structure and I/O allocation
Multi line 2 adopts standardized 8-slot backplates (Slot # 1~# 8) internally, with fixed functions for each slot, making it easy for engineering customization and on-site replacement. Understanding slot allocation is the first step in proper wiring:
Slot Function (GPC/PU) Function (GPU)
#1 power board (including status relay, 4 programmable outputs, open collector electrode pulse output, 5 binary inputs) is the same as GPC, but only has 4 outputs (no synchronous output)
#2 communication options (CANopen/Modbus/Profibus) are the same as GPC
#3 Load Distribution Board (± 5V active/reactive bus, ± 10V set value input, additional binary input and relays 5-8) Synchronous Control Board (G2 option only, including manual speed/voltage regulation input and relays 5-7)
#4. The output of the speed/voltage regulating relay (or optional analog/PWM output) is the same as GPC (but the voltage regulating output is only valid when the D1 option is selected)
#5 AC measurements (generator voltage, current, bus voltage) are the same as GPC (no bus voltage)
#6 analog transmission output (F1) or PWM droop (EF3) with GPC (F1 or F2)
#7 engine control cards (M1 or M2, including PT100, 4-20mA, speed, start/stop relay) are the same as GPC
#8 I/O extensions (7 binary inputs M13, or 4 relays M14, or 4 analog inputs M15, or engine communication H4/H5/H6) are the same as GPC, with additional load dependent start stop relay options
Engineering Tip: The terminal numbers for each slot are consecutive (e.g. # 1 is 1-28, # 2 is 29-36, etc.). Before wiring, be sure to refer to the terminal function table in the manual to avoid misconnection. Especially the current input terminal (73-78) of slot # 5 needs to be strictly connected according to s1/s2 polarity, otherwise the phase difference will cause power calculation errors.

Communication wiring: Voltage, current, and frequency measurement
1. Voltage input (terminals 79~89)