Complete Guide to DEIF GPU-3 Generator Protection Unit

Complete Guide to DEIF GPU-3 Generator Protection Unit

The reliability and flexibility of generator protection devices are directly related to power supply safety and equipment life in ship electric propulsion systems, marine engineering platforms, and land emergency power stations. The GPU-3 (Generator Protection Unit) launched by DEIF is a compact, fully digital microprocessor protection unit designed specifically for the protection, control, and monitoring of synchronous and asynchronous generators. Its rich protection functions, modular hardware architecture, and powerful programmable logic (M-Logic) make it an ideal choice for systems ranging from simple standalone to complex parallel systems. This article is based on the official technical data manual of GPU-3, and systematically reviews the protection functions, hardware structure, selection and configuration, communication interfaces, and engineering applications, providing a practical technical reference for electrical design engineers and on-site service personnel.

Product positioning and core features

GPU 3 is an independent generator protection device with a complete set of three-phase voltage/current measurement circuits (fully isolated) built-in, which can independently complete all-round protection of the generator. The core design concept is "on-demand configuration" - users can expand from the basic protection unit to a complete generator set controller with advanced functions such as synchronous grid connection, engine control, voltage regulation, analog output, etc. by selecting different software authorizations and hardware cards according to actual project needs.

List of Key Features:

Standard protection library: covering over 20 protection functions such as reverse power, overvoltage/undervoltage, overclocking/underfrequency, overcurrent (including definite time/inverse time), voltage imbalance, current imbalance, demagnetization, overexcitation, etc. (all corresponding to ANSI standard numbers).

Independent display and operation: Standard detachable display unit (DU-2), supports cabinet door installation (standard 3-meter cable), and can be expanded with up to two additional display screens or operation panels (AOP-1/AOP-2) through CAN bus.

Self diagnosis and redundancy: power on periodic self check, display in plaintext and drive status relay in case of fault; The engine control option includes a backup shutdown channel with independent power supply and processor, enabling safe shutdown in case of main processor failure.

M-Logic Micro PLC: A visual logic editor based on free PC software that allows users to assign specific functions or logic conditions to any input/output, enabling customized interlocking and control without the need for an additional PLC.

Full class society certification: meets the specifications of major classification societies and UL/cUL listings, and adapts to harsh marine environments.

Detailed explanation of comprehensive protection function

The protection functions of GPU 3 are organized according to ANSI standard numbering, and all protections have independent action values, delay, and on/off settings. Some protections also support multi-stage tuning (such as overcurrent 6-stage, undervoltage 3-stage, etc.) to meet the sensitivity and selectivity requirements of different operating conditions.

Protection function ANSI number can set segment number Typical applications

Generator reverse power of 32 2 segments to prevent stalling of the prime mover and protect the turbine/diesel engine

Generator overcurrent (timed/inverse time limit) 50/51 6-section+1-section inverse time limit phase to phase short circuit and overload protection, inverse time limit is used for thermal overload

Voltage dependent overcurrent 51V segment 1 reduces overcurrent setting at low voltage to improve sensitivity

Overvoltage/undervoltage (generator) 59/27 2-stage/3-stage prevention of excitation system failure or abnormal grid voltage

Over frequency/under frequency (generator) 81 each with 3 abnormal frequency protection segments to prevent turbine blade fatigue

Independent monitoring of grid connected busbars with over/under voltage and over/under frequency in multiple sections 59/27/81 to ensure grid connection conditions

Bus voltage imbalance 60 1 section detection bus side asymmetry fault

Current imbalance 46/60 1-stage protection generator stator winding asymmetric overheating

One section of demagnetization/overexcitation 40/32RV to prevent excitation system failure from causing generator out of step or iron core supersaturation

Reverse reactive power/leading phase 40 (power dependent) 1 section limits the generator from absorbing excessive reactive power from the system

In addition, the optional A package (power grid protection package) can also provide:

Time dependent undervoltage (27t)

Undervoltage and low reactive power (27Q)

Vector jump (78)

Frequency change rate (ROCOF, 81)

Positive sequence voltage low (27)

Directional overcurrent (67)

These features enable GPU 3 to not only serve as generator protection, but also as grid protection for grid connection points, meeting the requirements of distributed generation or islanding detection.