Description

The GE 369-HI-0-0-0-0​is a high-impedance differential protection relay from the GE Multilin 369 series,manufactured by General Electric(now part of GE Vernova).This specialized relay is engineered to provide ultra-sensitive and high-speed protection for critical motors,generators,and busbars by detecting internal faults that other protection schemes might miss.

Application Scenarios

In a large petrochemical complex,a 5000 HP induced draft fan motor is critical for furnace pressure control.A developing turn-to-turn fault within the motor stator winding might initially draw only a small unbalanced current,insufficient to trigger standard overcurrent relays,but it will generate destructive heat.Left unchecked,this fault can rapidly escalate into a ground fault or phase-to-phase fault,causing catastrophic motor failure,prolonged production loss,and potential safety hazards.The GE 369-HI-0-0-0-0​is deployed precisely for this scenario.Connected to Current Transformers(CTs)on both sides of the motor windings,it continuously compares the incoming and outgoing current.Any imbalance,indicating current leaking through an internal fault,is detected with extreme sensitivity.The relay can issue an alarm at the earliest sign of trouble for investigation or trip the motor instantaneously for a more severe internal fault,thereby preventing extensive damage and preserving both the valuable motor asset and continuous process operation.

Parameter

Main Parameters

Value/Description

Product Model​

GE 369-HI-0-0-0-0

Manufacturer​

GE Multilin(General Electric)

Product Category​

High-Impedance Differential Protection Relay

Protection Type​

High-Impedance(87)Differential Protection.The core function for detecting internal faults.

Application​

Protection of Motors,Generators,Busbars,Reactors.Guards high-value rotating and static electrical assets.

Inputs​

Current inputs from multiple sets of CTs(typically two or three).Measures current entering and leaving the protected zone.

Sensitivity​

Extremely High(can be set down to milliampere range relative to CT secondary).Capable of detecting incipient faults.

Operating Speed​

Very Fast(typically 1 to 2 cycles).Minimizes damage by clearing faults almost instantaneously.

Stability​

High stability through external stabilizing resistor.Remains secure during external faults with heavy through-fault currents and CT saturation.

Outputs​

Form-C relay contacts for Trip,Alarm,Auxiliary.Provides direct control and status signals.

Communications​

Optional serial communication modules(RS485,Ethernet)for integration.Enables remote monitoring and data retrieval.

Setting Adjustments​

Plug-in setting resistors or adjustable potentiometers for pickup and slope.Allows precise calibration for the specific application.

Technical Principles and Innovative Values

Innovation Point 1:Principle of High-Impedance Differential Protection.The GE 369-HI-0-0-0-0​operates on a classic yet supremely effective principle.The relay is connected in series with a stabilizing resistor across the differential junction point of the CT secondaries.Under normal load or during an external fault,the currents from the CTs on both sides of the protected equipment circulate and cancel out,resulting in minimal voltage across the relay.However,an internal fault creates an imbalance,causing a spill current to flow through the high-impedance path of the relay.This generates a significant voltage,quickly operating the relay.This design’s elegance lies in its simplicity,speed,and inherent immunity to CT saturation during external faults,making it exceptionally secure and reliable.

Innovation Point 2:Unmatched Sensitivity for Incipient Fault Detection.Unlike standard overcurrent relays that require a fault current magnitude of several hundred percent of motor full-load current,the 369-HI-0-0-0-0​can be set to detect imbalances as low as a few percent.This allows it to identify developing faults like turn-to-turn shorts in their earliest stages.This early warning capability is the cornerstone of predictive protection,enabling maintenance to be scheduled proactively to rewind or repair a motor before a minor fault escalates into a complete burnout,offering tremendous savings in repair costs and downtime.

Innovation Point 3:Inherent Security and Simplicity.The high-impedance scheme provides natural security against maloperation.The stabilizing resistor ensures that even if one set of CTs saturates completely during a severe external fault(a common cause of false trips in other differential schemes),the voltage developed across the relay remains below its operating threshold.This makes the GE 369-HI-0-0-0-0​incredibly dependable.Furthermore,its design is largely based on passive components and simple voltage supervision,resulting in a robust device with fewer potential points of failure compared to complex numerical relays for the same function,which is often a desired trait for a last-line-of-defense protection element.

Application Cases and Industry Value

Case Study:Protecting a Critical Circulating Water Pump Motor in a Power Plant.A nuclear power plant relied on massive circulating water pump motors to provide condenser cooling.A failure of one motor could force a unit derate.The plant installed GE 369-HI-0-0-0-0​relays on these critical 4000 HP motors.During a routine start of one motor,the relay issued an instantaneous trip.Initial checks of standard overcurrent and ground fault relays showed no cause.Investigation guided by the differential relay’s action focused on the motor itself.Testing revealed a developing short between turns in one phase of the stator winding—a fault that occurred during the high-stress starting period but had not yet evolved into a major fault.Because the 369-HI-0-0-0-0​acted so sensitively and quickly,the damage was localized.The stator was repaired in a workshop during a planned outage window at a fraction of the cost of a full rewind or a new motor.More importantly,it prevented a forced outage that would have had significant financial and grid reliability implications.This case underscores the relay’s value as a”financial insurance policy”for irreplaceable rotating assets.

Related Product Combination Solutions

Complete motor protection and control often involves layering the GE 369-HI-0-0-0-0​with other devices:

GE Multilin 469:A comprehensive motor management relay providing thermal overload,unbalance,ground fault,and starting protection.The 369-HI​provides dedicated internal fault backup.

GE Multilin 869:A high-end motor protection relay with advanced communications and diagnostics,often used as the primary protector with the 369-HI​as a dedicated differential backup.

GE 269Plus:A versatile motor protection relay for less critical applications where a standalone 369-HI​might be used.

Current Transformers(CTs):Matched sets of high-quality,low-reactance CTs with identical ratios are absolutely critical for the proper operation of the 369-HI-0-0-0-0.

External Stabilizing Resistor:A precision power resistor calculated for the specific application to ensure stability.

GE F650:A bay controller or feeder protection relay that could receive a trip signal from the 369-HI​via hardwired contacts or communication.

Test Switches&Blocks:Specialized test equipment for safely isolating and testing the differential circuit without disturbing the CT connections

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