© 2015 Eaton. All Rights Reserved. Motor Protection & Communication for Critical Loads Darrell Ouellette Technology Application Specialist

2 © 2015 Eaton. All Rights Reserved. Motor Protection & Communication for Critical Loads Electrical motors are used to convert electrical energy into mechanical energy that drive industry processes. Unexpected downtime of these processes can impact revenue, safety, and quality of life. When motors are used on critical loads, motor protection is an essential component and can provide energy savings, increased productivity, prevent premature failures and extend equipment life.

3 © 2015 Eaton. All Rights Reserved. What Causes Electrical Motor Failures? Power and power quality issues Thermal conditions Electrical Mechanical Other Bearing issues Mounting and alignment Environment Motor selection and sizing

4 © 2015 Eaton. All Rights Reserved. Motor Life Reduction when Overheated One of the primary causes of electrical motor failure is excessive heat, which is caused by: Over Current (current greater than FLA) High ambient temperature Poor ventilation

5 © 2015 Eaton. All Rights Reserved. Motor Life Reduction when Overheated

6 © 2015 Eaton. All Rights Reserved. How to Protect a Motor from Excessive Heat Use a motor protection relay or more commonly known as an overload relay. A motor protection relay is used to measure or calculate the motor thermal condition. When the motor protection relay determines that the motor temperature is beyond design limitations, it signals a power component to de-energize the motor.

7 © 2015 Eaton. All Rights Reserved. How to Protect a Motor from Excessive Heat Overload Relay Motor Contactor 3 Phase Power √√ X X √ √ Motor operating with normal conditions Motor operating with abnormal condition Overload relay sends signal for motor starter to open

8 © 2015 Eaton. All Rights Reserved. How to Protect a Motor from Excessive Heat Current is monitored over a period of time to calculate motor temperature. I 2 t protection curves are used.

9 © 2015 Eaton. All Rights Reserved. Motor Protection Overload Relay Types Bi-Metallic (Thermal) Overloads Basic Solid State (Electronic) Overloads Advanced Solid State (Electronic) Overloads

10 © 2015 Eaton. All Rights Reserved. Bi-Metallic (Thermal) Overload Relay Uses a strip composed of 2 metals with differing thermal characteristics. When heated the metals expand at different rates causing the strip to bend and trip the circuit.

11 © 2015 Eaton. All Rights Reserved. Bi-Metallic (Thermal) Overload Relay Can have fixed or adjustable settings. Different “heater” elements for different motor amperage and protection class. Offers basic current based protection only. Thermal overload Phase loss Ambient compensation. Not very accurate.

12 © 2015 Eaton. All Rights Reserved. Basic Solid State (Electronic) Overload Microprocessor based trip time calculations utilize thermal memory tables. Motor current is measured using CT’s. Usually self powered.

13 © 2015 Eaton. All Rights Reserved. Basic Solid State (Electronic) Overload Has a broad adjustable current range. Selectable trip class settings. Offers some advanced current based protections. Current unbalance Ground fault detection Very accurate

14 © 2015 Eaton. All Rights Reserved. Advanced Solid State (Electronic) Overload Utilizes much of the same technology as the Basic Solid State Overload. Has added features for critical loads. Voltage inputs for Line Protection Has features for Load Protection Typically has a display for indication. Has communications capability. Typically separately powered.

15 © 2015 Eaton. All Rights Reserved. Motor Protection Thermal Overload (Calculated) Definition: Thermal overload is a condition where current draw to a motor exceeds 115% of the full load amperage rating of an inductive motor Source: An increase in the load or torque that is being driven by the motor A low voltage supply to the motor would cause the current to go high to maintain the power needed A poor power factor would cause above normal current draw Result: Increase in current draw. Current leads to heat and insulation breakdown, which can cause system failure. Additionally, an increase in current can increase power consumption and waste valuable energy Bi-Metallic Overload Basic Solid State Overload Advanced Solid State Overload

16 © 2015 Eaton. All Rights Reserved. Motor Protection Phase Loss - Current (single-phasing) Definition: One of the three phase currents is not present Source: Multiple causes: loose wire, improper wiring, grounded phase, open fuse, etc. Result: Motor current increases in the remaining two phases to 1.73 times the full load current causing excessive heating in the motor Single-phasing can also lead to unwanted motor vibrations Bi-Metallic Overload Basic Solid State Overload Advanced Solid State Overload

17 © 2015 Eaton. All Rights Reserved. Bi-Metallic vs Electronic: Phase Loss

18 © 2015 Eaton. All Rights Reserved. Motor Protection Ground Fault Definition: A line to ground fault Source: A current leakage path to ground Result: An undetected ground fault can burn through multiple insulation windings ultimately leading to motor failure Basic Solid State Overload Advanced Solid State Overload

19 © 2015 Eaton. All Rights Reserved. Motor Protection Phase Imbalance (Voltage* and Current) Definition: Uneven voltage or current between phases in a three phase system Source: When a three phase load is powered with a poor quality line, the voltage per phase may be unbalanced Result: Unbalanced voltage causes large unbalanced currents and as a result this can lead to motor stator windings being overloaded, causing excessive heating, reduced motor efficiency and reduced insulation life * Only Advanced Solid State Overload can detect Voltage Imbalance Basic Solid State Overload Advanced Solid State Overload

20 © 2015 Eaton. All Rights Reserved. Motor Output During Phase Imbalance

21 © 2015 Eaton. All Rights Reserved. Motor Protection Jam Definition: Jam is similar to thermal overload in that it is a current draw on the motor above normal operating conditions Source: Mechanical stall, interference, jam or seizure of the motor or motor load Result: To drive the additional load the motor draws an abnormal amount of current, which can lead to insulation breakdown and motor failure Advanced Solid State Overload

22 © 2015 Eaton. All Rights Reserved. Motor/Line Protection Over-voltage Definition: When the line voltage to the motor exceeds the specified rating Source: Poor line quality Result: Lower than rated current draw and a poor power factor. A trip limit of 110% of rated voltage is recommended Advanced Solid State Overload

23 © 2015 Eaton. All Rights Reserved. Line Protection Under-voltage Definition: When the line voltage to the motor is below the specified rating Source: Poor line quality Result: Excessive current draw. This increases the heating of the motor windings and can shorten insulation life. A trip limit set to 90% of rated voltage is recommended Advanced Solid State Overload

24 © 2015 Eaton. All Rights Reserved. Line Protection Power-up Delay Definition: Allows for staggered starting of motors and loads after a power loss Source: When there is a power failure, or power cycle, multiple loads come on line simultaneously Result: Sags affect the operation of devices and may prevent successful start-up If power is lost to a motor driving a pump, it may be necessary to delay a restart to allow the pump to come to a complete stop to prevent backspin Advanced Solid State Overload

25 © 2015 Eaton. All Rights Reserved. Load Protection Phase Rotation (phase-reversal) Definition: Improper wiring, leading to phases being connected to the motor improperly Source: Improper wiring, leading to phases being connected improperly Inadvertent phase-reversal by the utility Result: Phase-reversal can cause unwanted directional rotation of a motor Possible mechanical failure and/or injury to an operator Advanced Solid State Overload

26 © 2015 Eaton. All Rights Reserved. Load Protection Under-Current and Low Power Definition: Average RMS current or average RMS power provided to the motor falls below normal operating conditions Source: A portion of the user's load disappears, caused by a broken belt, a dry-pump (low suction head) or a dead-headed centrifugal pump Result: Mechanical failure can or has occurred Running a pump dry or running a pump in a dead-headed condition can cause excessive heating, damaging expensive seals and breaking down desired fluid properties Advanced Solid State Overload

27 © 2015 Eaton. All Rights Reserved. Load Protection High Power Definition: The motor load is drawing more power than expected at normal operating conditions Source: This is typical of batch processing applications where several ingredients flow into a mixer. Out of-tolerance conditions can be detected using the High Power and Low Power settings A second cause is when a positive displacement pump is pumping into a closed valve Result: If a high power fault goes undetected the result may be a batch of material that does not meet specification If a high power fault goes undetected in a positive displacement pump application the result is severe mechanical failure of the weakest link Advanced Solid State Overload

28 © 2015 Eaton. All Rights Reserved. Motor Life Reduction when Overheated The primary cause of electrical motor failure is excessive heat, which is caused by: Over Current (current greater than FLA) High ambient temperature Poor ventilation

29 © 2015 Eaton. All Rights Reserved. Motor Protection Thermal Overload (Measured) Definition: Thermal overload is a condition where the measured winding temperature exceeds the motor design limitation. Source: In addition to the current conditions that cause a thermal overload, the sources below can cause increased thermal conditions. Ambient temperature. Reduced cooling capacity. Result: Operating above the designed ambient temperature can lead to heat and insulation breakdown, which can cause system failure. Restricted motor cooling will also lead to increased winding temperature. Advanced Solid State Overload

30 © 2015 Eaton. All Rights Reserved. Motor Protection Thermal Overload (Measured) Advanced Solid State Overload Overload Relay Motor Contactor 3 Phase Power Temperature A thermistor embedded in the motor windings will give an indication when the temperature design limit is exceeded. RTD’s embedded in the motor windings will provide a measured value of the winding temperature. This temperature feedback can be used to set alarm and shutdown levels.

31 © 2015 Eaton. All Rights Reserved. What Causes Electrical Motor Failures? Power and power quality issues Thermal conditions Electrical Mechanical Other Bearing issues Mounting and alignment Environment Motor selection and sizing

32 © 2015 Eaton. All Rights Reserved. Motor Protection Bearing Temperature Advanced Solid State Overload Overload Relay Motor Contactor 3 Phase Power Temperature RTD’s embedded at the motor bearings will provide a measured value of the bearing temperature to indicate bearing problems. This temperature feedback can be used to set alarm and shutdown levels.

33 © 2015 Eaton. All Rights Reserved. Motor Protection Relay Comparison FeatureBi-MetallicBasic Solid StateAdvanced Solid State Thermal OverloadXXX Phase LossXXX Ground FaultXX Phase ImbalanceXX Motor JamX Over/Under VoltageX Power Up DelayX Phase RotationX Over/Under PowerX Thermistor or RTDX AlarmsX CommunicationsX

34 © 2015 Eaton. All Rights Reserved. Advanced Solid State Basic Solid State Bi-Metallic Motor Protection Relay Value Map Performance Price

35 © 2015 Eaton. All Rights Reserved. Selecting a Motor Protection Relay Critical Load? Lost production and revenue Safety system Quality of life Performance vs Price. Process Up-time Requirement. Fault based maintenance Time based preventative maintenance Predictive based preventative maintenance

36 © 2015 Eaton. All Rights Reserved. Motor Protection Enhancements Motor Management Systems Protection Monitoring Control Motor efficiency monitoring. Motor condition (wellness) monitoring.

37 © 2015 Eaton. All Rights Reserved.