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VFD-Driven Motor Applications

The Multilin 869 provides protection for motors fed through VFDs (Variable

Frequency Drives). A wide range of the frequency tracking (3-72Hz) allows

the 869 to track the motor frequency and adjust its sampling rate to

accurately measure phasors. An advanced algorithm allows switchable

current and voltage tracking in case VFD is bypassed.

Thermal protection also considers the extra heating generated by the

higher harmonics due to VFD to achieve the accurate response to the

actual motor heating. RMS currents fed to the various motor protection

elements are further processed through the averaging filter to eliminate

oscillations in current signals to ensure the security.

Additionally, users may indicate a  starting  VFD  frequency  that  helps

the device to track the motor frequency faster and therefore accurately

measures the phasor quantities, which, otherwise, could cause delayed or

false protection operation of the protection.

Multilin 869 Overview

The Multilin 869 Motor Protection System is a protection device

designed for the management, protection and control of medium to large

horsepower motors. The 869 provides comprehensive protection and

control of various types of motors with different loads they run.

Protection & Control

As part of the 8 Series family, the Multilin 869 provides superior protection

and control. The 869 offers comprehensive protection and control solutions

for medium and large motors for various applications. It contains a full range

of selectively enabled, self contained protection and control elements.

Recent enhancements include the following:

Starting Control

• Start sequence control

• Reluctance torque synchronization

• Incomplete start sequence

• Stabilizing feature

• Auto loading and unloading feature

Squirrel Cage Rotor Thermal Protection (separate from the main

thermal model)

• Time vs speed curve based

• Reduced voltage starting feature

Enhanced Thermal Protection with Speed Biasing

Enhanced power factor protection

• Ride-through feature – directly trips motor

• Resynchronization feature – allows motor to re-synchronize instead of

tripping

High-Inertia Load Applications

The voltage dependent overload curve feature in Thermal Model is

tailored to protect motors which are used in high inertia load applications.

Voltage is continually monitored when the motor is started and during

acceleration. The thermal limit curve is then adjusted accordingly. This

enables the Multilin 869 to distinguish between a locked rotor condition,

an accelerating condition and a running condition.

This feature acts as an additional check of the amortisseur, or squirrel

cage winding rotor heating. This feature uses estimated speed-dependent

thermal capacity used (actual value ‘’ and compares this value to the

Thermal Capacity Used calculated by the current-based and RTD Bias

(when Enabled) methods. The larger of the three values is used from that

point onward.

Thermal Model with Speed Biasing

This feature acts as an additional check of the amortisseur, or squirrel

cage winding rotor heating. This feature uses estimated speed-dependent

thermal capacity used (actual value ‘’ and compares this value to the

Thermal Capacity Used calculated by the current-based and RTD Bias

(when Enabled) methods. The larger of the three values is used from that

point onward.

RTD Biasing

The Multilin 869 supports up to 13 programmable RTD inputs that can

be configured for an Alarm or Trip. The RTD voting option gives additional

reliability to ignore any RTD failures.

The RTDs can be assigned to a group for monitoring the stator, bearing and

ambient temperatures.

The Thermal Model is also biased by the RTD’s temperature feedback. This

feature allows the relay to protect the motor against unusual high ambient

temperatures or abnormal heating due to overvoltage or damaged

bearings. The RTD biasing feature can correct for this temperature rising

by forcing the TCU register up to the value appropriate to the temperature

of the hottest stator RTD.

Power Factor Based Regulation

Motor Thermal Model

Many motor failures are directly or indirectly related to, or caused

by, extensive heating of the different motor parts involved in

electromechanical operation. Proven through several generations of GE’s

Multilin motor relays, an enhanced thermal model is used in the 869 relay

with seven major features:

Motor thermal limit curves – NEMA® standard, voltage dependent and

customized motor curves

• IEC 60255-8 thermal overload curves

• Smoothing filter for cyclic loads

• Current unbalance biasing

• Independent running and stopped exponential cooling curves

• Optional RTD biasing of the thermal model to adapt to real-time

temperature measurements

• Compensation for hot/cold motor condition

The flexibility of the Multilin 869 thermal models allows for proper set up

and performance for applications, including high inertia and cyclic loads.

Recent enhancements include the following:

Starting Control

• Start sequence control

• Reluctance torque synchronization

• Incomplete start sequence

• Stabilizing feature

• Auto loading and unloading feature

Squirrel Cage Rotor Thermal Protection (separate from the main

thermal model)

• Time vs speed curve based

• Reduced voltage starting feature

Enhanced Thermal Protection with Speed Biasing

Enhanced power factor protection

• Ride-through feature – directly trips motor

• Resynchronization feature – allows motor to re-synchronize instead of

tripping

Applications

• Wide range of motor applications for oil & gas, mining & metals, cement, and wastewater

• Comprehensive protection and management of medium to large motors; two-speed, VFD-driven,

cyclic loading and synchronous motors

• Specific and advanced features for high inertia loads and reduced-voltage starting motors

• Stator and rotor protection of medium to large synchronous motors

• Synchronous motor DC field excitation application control

• Advanced predictive motor diagnostics and motor health visualization

Multilin 869 Overview

The Multilin 869 Motor Protection System is a protection device

designed for the management, protection and control of medium to large

horsepower motors. The 869 provides comprehensive protection and

control of various types of motors with different loads they run.

Protection & Control

As part of the 8 Series family, the Multilin 869 provides superior protection

and control. The 869 offers comprehensive protection and control solutions

for medium and large motors for various applications. It contains a full range

of selectively enabled, self contained protection and control elements.

Key Benefits

• Comprehensive motor protection for medium and large induction and  synchronous motors

• User-configurable Single Line Drawing on color display for local control, system status, and metering

• Advanced motor diagnostics with comprehensive fault and disturbance recording

• Integrated arc flash detection using light sensors supervised by overcurrent to reduce incident

energy and equipment damage

• Advanced cyber security including features such as AAA, Radius, RBAC, and Syslog helps enable

NERC® CIP requirements

• Draw-out design simplifies testing and increases process uptime

• Supports the latest in communication protocols and networking technology, enabling seamless

system integration and interoperability

• Optional Wi-Fi connectivity minimizes system configuration and facilitates safe relay programming

and diagnostic retrieval

Multilin 869

Comprehensive Motor Protection and Management for Medium and Large Motors

The Multilin™ 869 relay is a member of the Multilin 8 Series protective relay platform and has

been designed for the protection, control and management of medium and large induction and

synchronous motors.

The Multilin 869 provides advanced functionality for various types of applications such as high-

speed protection, extensively customizable programmable logic, advanced motor monitoring and

diagnostics, and flexible configuration capabilities.

The Multilin 869 is now available with an integrated synchronous motor protection module for

protection and control of synchronous motors.

Advanced communications in the 8 Series platform allows easy integration into process and electrical

control systems for smoother asset monitoring and control.

Applications

• Single/dual feeder applications for utility, oil & gas, mining & metals, process industry,

commercial, and waste water segments

• Fast protection pass enabling load shedding schemes

• Reliable automatic bus transfer & autoreclose schemes

• Bay controller for wide range of switchgear applications

• High speed fault detection for arc flash mitigation

Multilin 850 Overview

The Multilin 850 is an advanced feeder protection device designed

for high performance, protection, control and monitoring of incoming

and outgoing feeders.

With up to 57 digital inputs and 22 digital outputs in a compact box,

the 850 provides a versatile and cost effective control, protection,

measurement & monitoring solution. Flexelements and Flexlogic

enable users to customize schemes to meet a variety of applications.

From dual main to main-standby configurations, the

Multilin 850D delivers a more economical and reliable solution,

enabling customers to reduce hardware requirements and simplify

device integration, including safe and secure Wi-Fi communications

for system configuration and diagnostics.