1. MPU-16A
MOTOR PROTECTION UNIT

2. THE MPU-16A MOTOR PROTECTION UNIT
The MPU-16A is a microprocessor-based motor protection unit that uses thermal modeling techniques to extend motor protection beyond the limits of other electronic overload relays. These thermal modeling techniques permit an MPU-16A to continuously track the used thermal capacity of a motor through starting, running, overload, and cooling cycles.

3. WHAT DOES AN MPU-16A OFFER?
Thermal protection
Overcurrent protection
Undercurrent protection
Current-unbalance protection
Phase-reverse protection
Temperature protection
Earth-fault protection
Short-circuit protection
Compact design (1/4 DIN) (96mm x 96mm)
Non-volatile memory
Temperature rating of °C to 60°C
Panel or surface mount
Fused form “C” output contacts
Program-change lockout
CSA-NRTL certification, compliance to IEC

4. MPU-16A FACE PLATE & OPERATOR INTERFACE
TRIP/ALARM, Red LED
On: Trip or alarm
Flashing: Program-change lockout defeated
PROCESSOR, Green LED Indicator On: Processor functional
RAMP switch:
Adjusts value digits
MODE switch:
Selects modes “0” through “F”
RESET switch:
Resets trips and alarms
ENTER switch:
Enters values, accesses alarm set points and values at trip
LIQUID CRYSTAL DISPLAY
MODE digit: Identifies mode
VALUE digits: Display set points, trip-and-alarm codes, and meter readings
MEMBRANE SWITCH KEYPAD
MODE LIST
The faceplate of the MPU consists of 4 sealed bubble buttons for programming, a liquid-crystal display, two LED’s for indication, and Mode lists.
The first digit of the display is the mode indication. There are set-point modes that store the programmable trip and alarm set points, and to store motor data. These include I2t Limit 600%FLA), Overcurrent (%), Undercurrent (%), Current Unbalance (%), Temperature (deg. C), Earth Fault (%), Full-Load Current (A), and motor Service Factor (%) , and CT Primary Ratings (A).
There are also status modes that enable you to view Ammeter (A)(%), Peak Current (A), Current Unbalance (%), Temperature (deg C), Earth Leakage (A), and percent I2t.
The value displayed is the value of the set-point or reading in the designated unit. If the Enter button is pressed the LCD will display the alarm set points while in set-point mode or the last trip value while in a status mode.
The Ramp and Mode buttons are used to scroll through set point values and to select the appropriate mode for viewing. To change scrolling direction release the button and re-press within one second.
The red LED indicates a trip-or-Alarm if on constantly and indicates that programming is enabled active when it is flashing. The green LED indicates that the MPU-16A microprocessor is functioning properly.

5. MOTOR INSULATION CLASSES
180
356
15
160
155C
320
10
HOT SPOT ALLOWANCE
140
284
130C
10
125
120
248
105C
105
100 5
212
TEMPERATURE (°C)
TEMPERATURE (°F)
TEMPERATURE RISE
80 80
176
Motors are divided into classes according to the thermal endurance of the system.
Class F and H are the most common insulation classes; for this presentation we will discuss class F.
Temperature rise (yellow) is taken from an ambient temperature of 40 degrees Celsius.
Class F has a temperature rise of 105 degrees. The average winding temperature rises as determined by the resistance method.
Class F has a hot spot allowance (red) of 10 degrees C: a provision for the winding temperature in the slot being higher than the average winding temperature.
This gives class F a maximum temperature of 155 degrees Celsius. This means if we do not run the motor above 155 degrees Celsius then we can expect maximum insulation life.
60 60
140
AMBIENT TEMPERATURE 40
104 20
40
40
40
40 68 32 A B F H
INSULATION CLASS

6. MOTOR INSULATION LIFE - TEMPERATURE RELATIONSHIP
7 YEARS
100
110
120
130
140
150
160
180
200
220
240
260
280
300
100,000
— 10
NORMAL LIFE
— 7
50,000
APPROX. 7 YEARS
— 5
YEARS
10,000
CLASS H
— 1
5000
CLASS F
— 5
MONTHS
CLASS B
— 2
1000
— 1
AVERAGE LIFE (HOURS)
500
CLASS A
— 20
— 10
— 5
DAYS
100
The life of the machine should not be excessively shortened due to overheating.
Because the deterioration of the insulation is both a function of time and temperature, the operating temp of a machine is closely related with its life expectancy.
NEMA states that the time-to-failure of organic insulation is halved for each 8 to 10 deg C rise above the motor insulation class.
This can be seen on this graph. If we take our Class F insulation and come up the 155 degree Celsius line, we see the Class F curve intercept at 7 years. If we raise the temperature to 165 degrees Celsius (+10 deg) we see the motor life is cut in half; 3.5 years.
— 3 50
— 2
— 1 10 5 1
100
110
120
130
140
150
160
180
200
220
240
260
280
300
HOTTEST TEMPERATURE ( C)

7. I 2t THERMAL PROTECTION - Mode 0 (CLASS 20 EXAMPLE)
ULTIMATE CURRENT RANGE: 100% TO 125% FLA
ULTIMATE CURRENT SHOWN AT 115% FLA
CLASS 20
0%12t
25% I2t
50% I2t
75% I2t
CLASS RANGE
1 s TO 45 s AT 600%
OVERCURRENT TRIP
RANGE 100% TO 600%
IN RUN STATE
PERCENT MOTOR FLA 50
100
PERCENT I2t
DYNAMIC LIMIT
SF=1.00
SF=1.15
SF=1.25
200
300
400
500
600
700
800
900
1000 1 2 3 4 6 8 10 20 30 40 60 80
2000
3000
4000
6000
8000
10000
THERMAL MODEL INGREDIENTS
Full-load current
Service factor
Locked-rotor current
Cold locked-rotor time (motor class)
SECONDS to TRIP
The thermal model is always being updated.
The unit will trip at 100% I2t.
I2t must decrease to 30% before a Mode 0 trip can be reset.
An alarm set point may be programmed.
Thermal Tracking. The MPU-16A’s thermal model dynamically tracks the motor’s used thermal capacity (I2t).
Shown is a semi-log graph of the percent of motor FLA versus the time-to-trip (100% I2t) in seconds. There are 1170 protection curves available in the MPU-16A: 100% to 125% service factor (26 steps), and 600% FLA cold trip times of 1 to 45 seconds—26 X 45=1170.
The upper portion of the curve shows the continuous running protection at service factors of 1.0 to 1.25: 1.15 is shown. The lower portion of the curve shows locked-rotor protection. FLA is the 100% point on the X-axis. The curves shown are for a Class 20 motor. From cold it will trip in 20 seconds at 600% full load current. At100% I2t the motor has reached its maximum rated temperature. The curve constantly updates and changes, hence the term dynamic thermal tracking. Four of the 101 (0-100% I2t) possible class 20, 1.15 s.f. motor curves are shown. The cold curve (0% I2t) is the uppermost, with 25%, 50% and 75% used thermal capacity curves also shown. When the motor has used all of its thermal capacity (100% I2t), the curve is a vertical line, and the MPU-16A trips.
The percent I2t dynamic limit curve (top right) illustrates to what percentage I2t the motor will tend for different currents and service factors. For example, a 1.15 s.f. motor operating at 100% FLA will reach an equilibrium point of 75% I2t.
NEMA definition of thermal O/L: If a motor is run at rated current and rated s.f. then the motor will reach rated temperature rise, and a thermal overload relay must trip.
PERCENT MOTOR FULL LOAD CURRENT

8. Plug-in wire-clamping terminal blocks
MPU-16A BACK PLATE
Plug-in wire-clamping terminal blocks
L1 and L2 - are for control power. Units can be ordered as 120 Vac or 240 Vac and 50 or 60 Hz. There is also an optional ac/dc switching power supply, various dc supplies, and a 120/240 Vac switch selectable power supply available.
are the form “C” trip relay. It is 10 A rated and fused at 8 A. Relays can be configured to operate in the fail-safe or non-fail-safe mode.
8 - System ground
9 - Key Pin. High voltage lower terminal block cannot be plugged into low voltage upper terminals.
Form “C” alarm relay.
isolated analog output or RS-485.
Earth-fault CT input.
Program enable. These pins must be connected to allow
set point changes.
Input for RTD or Thermistor.
ICT-2 Interface CT input. ICT-2 shown on the next slide.

9. ICT-2 INTERFACE CURRENT TRANSFORMER
TB3
TB2
TB1 27 1 26 R 25 5 24 S 23 E 22 21 20 X Y 19 F 18 17 16 15 2 C O M 14 13 B A 3 4 6 7 8 9 10 11 12
DIMENSIONS: 3.4”h x 4.43”w x 2.07”d

10. ICT-2 INTERFACE CT CONNECTION
STOP
START
TO MOTOR
SUPPLY
ICT-2 Interface CT minimizes CT-lead length and terminates CT’s.
The MPU-16A comes complete with the ICT-2, 6 m of interconnection cable, and mounting hardware.
Phase CT’s and the Earth-Fault CT are connected to the ICT-2. The ICT-2 accepts both 1 A and 5 A CT-secondary windings. The ICT-2 should be placed close to the current transformers to reduce CT lead length, and burden. This also minimizes electrical noise picked up by the CT leads. The ICT-2 terminates all of the CT’s connected to it. This eliminates open-CT hazards should the MPU-16A be removed from service. The ICT-2 output is communications signal strength (thus not a hazard if open) and is carried to the MPU-16A via a 6 conductor shielded cable. This modular approach to interface current transformer design allows the main control unit to be mounted where most convenient for observing, programming, etc, while the CT connection is made close to the CT’s. With the Startco MPU-16A there is no trade-off between convenience and function. Competitive motor protection relays all include their interface current transformers as part of the main package necessitating such a trade-off.
ICT-2 connections may be made such that ground-fault protection is provided without a separate earth-fault CT, as a residual connection. As few as two phase CT’s may be used, with the third phase being derived.
On the bottom of the ICT-2 are shorting screws. These screws must be removed to isolate Phase-CT and Earth-Fault-CT secondaries for in-line applications. Shorting screws must not be removed for residual or two-CT applications.

11. SET-POINTS % CT-PRIMARY CURRENT UNBALANCE MOTOR CURRENT MOTOR CURRENT
TRIP SET POINT TRIP TIME = 250 ms
ALARM SET POINT ALARM TIME = 250 ms
100%
OVERCURRENT
600%
MOTOR CURRENT
100%
ALARM SET POINT ALARM TIME = 1s
TRIP SET POINT TRIP TIME = 5s
15%
UNDERCURRENT
MOTOR CURRENT
CURRENT UNBALANCE 5%
75%
TRIP SET POINT TRIP TIME = 5s
ALARM SET POINT ALARM TIME = 1s
220°C
50°C
RTD TEMPERATURE °C
TRIP SET POINT TRIP TIME = 1s
ALARM SET POINT ALARM TIME = 1s
TEMPERATURE
Overcurrent- “jam” or “stall” protection, and is active only after the motor is up to running.. Overcurrent alarm and trip set points are selectable from 100% to 600% of motor full-load current.
TRIP SET POINT
TRIP DELAYS = I NST., 0.25, 0.5, OR 1.0 s
ALARM SET POINT ALARM TIME = 1s 1%
EARTH-FAULT
100%
% CT-PRIMARY

12. START-RUN CURRENT ENVELOPE%
SHORT CIRCUIT TRIP
1200
PERCENT
MOTOR
FULL LOAD
CURRENT
OVERCURRENT TRIP
OC SETPOINT
The MPU-16A considers the motor to be running only after it draws between 10% and 125% of full-load current for a continuous period of 10 seconds. After this occurs overcurrent and undercurrent protection is enabled. A motor drawing 10% FLA, or less, is considered to be stopped. Over 1200% is considered to be a short circuit, if short-circuit protection is enabled.
Note: I2t, Unbalance, Earth Fault, Phase Reverse, and Temperature are always active.
Because I2t protection is always present the motor is protected during a prolonged start, even though overcurrent protection has not yet been activated.
125
UC SETPOINT
UNDERCURRENT TRIP 10
TIME OK
10 s
TRIPPED
STOPPED
STARTING
RUNNING
STOP

13. BPU-2A BEARING PROTECTION UNIT
RTD 1
STATOR
RTD
RTD 2 t°
120 VAC L N
TO 17, 18, 19
ON MPU-16A
BPU-2A S H 1 2 C W T A B
TRIP
ALARM
The BPU-2A Bearing Protection Unit can be used as a stand-alone relay, or can be used as an input to the MPU-16A.
The BPU-2A monitors two bearing RTD’s, and cam be programmed to alarm and trip on absolute temperature, or on a temperature difference between the two bearings.
If it is used as an input to a MPU-16A, a stator RTD is also connected to the BPU-2A. When an overtemperature trip occurs in this configuration, one must consult the BPU-2A to determine which RTD caused the trip.

14. MPU-16A SETUP
MODE 8 - PROGRAM SELECTIONS Phase reverse Phase sequence Earth-fault delay time Hot-motor compensation Short-circuit trip Latching alarms Autoreset on thermal trip Operating mode of output relays Isolated analog-output parameter
MODE 6 – FULL LOAD CURRENT -Range 0.45 to 0.93 x Phase-CT- Primary Rating (0 to 800 A)
MODE 7 – SERVICE FACTOR -Range 100% to 125% in 1% steps
MODE F – CT PRIMARY RATINGS First Level: Phase-CT Primary Rating (A)
Second Level: Earth-Fault-CT Primary Rating (A)
MODE 0 – I2t LIMIT -Range 1 s to 45 s in 1 s steps
Mode 7 is used to enter the motor’s service factor and to indicate the MPU-16A’s hardware configuration. Service factor is the factor by which the ultimate-trip current exceeds the full-load current entered in Mode 6. The hardware configuration code is displayed by pressing Enter.
The set-point range is 100% to 125% in 1% increments.
NOTES:
ENTER switch must be pressed within 3 seconds of releasing RAMP switch or display will return to original value. Jumper must be installed between terminals 20 and 21

15. MODE 8 - PROGRAMMING: 1 st LEVEL
Mode 8 is the program mode. Use the tables to make selections of how the MPU-16A is to operate. Select the number, 0 to F, that corresponds to the required combinations of zeros and ones, and program it into the appropriate value digit. For example, in value digit 2, phase sequence ABC, phase reverse enabled, earth-fault trip time of 1.4 s, gives a combination of 0110, which corresponds to the number 6. Enter 6 into value digit 2. Another example: in value digit 3, hot motor compensation on, short circuit protection on, no alarm latching, auto-reset enabled, gives a combination of 1101, which corresponds to the number D. Enter D into value digit 3. For this example the display of the MPU-16A will read 806D.

16. MODE 8 - PROGRAMMING: 2 nd LEVEL - w/o communications
The second level of Mode 8 is not the same for units with or without communications.

17. MODE 8 - PROGRAMMING: 2 nd LEVEL - with communications

18. STATUS MODES or METERING MODES
MODE 9 — Ammeter (A) or (%)
MODE A — Peak current (A)
— Percent current modulation
MODE b — Current unbalance (%)
MODE C — Temperature (°C)
MODE d — Earth leakage (A)
MODE E — Percent I2t
—Minutes to reset
All Modes - Meter values-at-last-trip
Status modes are displayed to provide real-time information of each protective function. Running information is available for each status mode as well as historical information useful for troubleshooting. When a trip occurs all status mode values-at-trip are stored in non-volatile memory. These values are displayed when the Enter switch is press while in the appropriate mode. The values are over-written with new data when another trip occurs.
Units purchased with the data logging option will store up to 250 such records.

19. EMERGENCY THERMAL RESET - Mode E
Used I2t reduced to 0%
Thermal overload is reset
RTD trip is temporarily disabled
Occasionally it is desired or required to restart a motor, that has tripped on thermal capacity, before the used thermal capacity reduces to 30%, the point at which a normal Mode 0 reset may be accomplished. The motor protection unit’s thermal model is reset to zero and temperature protection is temporarily disabled by performing an “Emergency Thermal Reset”. Select Mode E, enable programming, press Reset and Enter simultaneously.
Main purpose of having a special emergency thermal reset is to force the user to make a conscious decision to restart the motor

20. MPU-16A TYPICAL APPLICATION
CONTACTOR K1
EARTH-FAULT CT
PHASE CT’S
MOTOR
SUPPLY
PROGRAM ENABLE t°
TEMPERATURE SENSOR N L
ANALOG OUTPUT
START
STOP K1 A
ALARM K1

21. OPTIONAL RS-485 COMMUNICATIONS23 24
SE-485
T(A)
T(B)
R(A)
R(B)
SE-TA485
FR. GND
TD(B)
TD(A)
RD(A)
RD(B)
+12VDC
GND
WHT
BLK
RTS SD ON
OFF
CONTROL
ECHO
TD ENABLE RD
RS-232 TO RS-485 CONVERTER (485CSP2)
RS-485
RS-232
DC POWER SUPPLY
SHIELD 23 24
OPTIONAL DATA LOGGING: Store up to 250 time-stamped records: Meter data at sample time -Pre-trip meter values -Protection mode set points -Time or event trigger modes 23 24
SE-485 23 24
1 TO 63 MPU-16A’s or
FPU-16’s
SE-TA485
RS 232

22. DATA-LOGGING FILE IMPORTED INTO EXCEL

23. MPU-16A COMPLETE ORDERING NUMBER
MPU-16A - P P
Mounting Style
P = Panel, S = Surface
Options
No Options = 00
Backlit Display = 01
Remote-Keypad Input = 02
Backlit Diplay & Remote
Keypad Input = 03
RS-485 Comm, A-B Protocol = 10
RS-485 Comm, Modicon = 11
RS-485 A-B, Data Logging = 20
RS-485 Modicon, Data Logging = 21
Supply Voltage
12 = 120 Vac, 24 = 240 Vac
SW = Switch Selectable 120/240Vac
AD = Switching 120/240 Vac/dc
D1 = 12 Vdc, D2 = 24 Vdc
D3 = 48 Vdc
Load Frequency
5 = 50 Hz, 6 = 60 Hz
Temperature Sensor Input
P10 = RTD 100  Platinum
N10 = RTD 100  Nickel
N12 = RTD 120  Nickel
C01 = RTD 10  Copper
PTC = PTC Thermistor
Signal-Output Configuration
4 -20 mA Analog only = 42
0 -5 Vdc Analog only = 05
0 -10 Vdc Analog only = 01
RS-485 Communications only = 00
RS-485 & 4-20 mA Analog (Current) = 91
RS-485 & 4-20 mA Analog (I2t) = 92
RS-485 & 4-20 mA Analog (Earth Leakage) = 93
RS-485 & 4-20 mA Analog (Temperature) = 94

24. PMA PANEL MOUNT ADAPTORS
MPU-16A Panel Mount Adapters available for: PMA: Multilin P4A PMA-1: Multilin 169 or 269 PMA-2: Allen-Bradley 1406 PMA-4: Multilin 139 or 239 PMA-7: GE Lodtrak II* PMA-9: GE S1 PMA-10: GE Lodtrak III*
*Rackout retrofits are available for Lodtrak, P&B Gold, etc.
PMA-1

25. P & B GOLD to MPU-16A UPGRADE