Motortronics MVC Plus User Guide

MVC Plus User Manual: 2.3 – 7.2kV Class

Table of Contents

PAGE

Chapter 1: Introduction .................................................................................................................. 1

1.1 Overview ..................................................................................................................................... 1

1.2 Specifications ...........................................................................................................................1-2

1.3 Reference Chart ......................................................................................................................... 3

1.4 Design Features ......................................................................................................................... 4

1.5 Theory of Operation .................................................................................................................4-5

1.6 General Protection ...................................................................................................................5-6

1.7 Thermal Overload Protection ...................................................................................................... 6

1.8 Firing Circuit ................................................................................................................................ 7

1.9 Electronics .................................................................................................................................. 8

Fig. 1.9 Keypad Interface ............................................................................................................ 8

Chapter 2: Connections ............................................................................................................... 10

2.1 Warnings .................................................................................................................................. 10

2.2 Control Connections ................................................................................................................. 11

2.2.1 TCB Board ............................................................................................................................. 10

Fig. 2.2.1 TCB Terminal and Control Board .............................................................................. 10

2.2.2 Description of Terminal Connections ................................................................................. 12-14

2.2.3 Description of Jumper Selections and Functions .................................................................... 15

2.2.4 Description of Switch Settings and Functions ......................................................................... 15

2.2.5 Description of LED Indicator Functions .................................................................................. 16

2.3 Circuit Board Layout Reference Section .............................................................................. 17-19

Fig. 2.3.1 Optional RTD Board .................................................................................................. 17

Fig. 2.3.2 RS485 / RS422 Communications Board .................................................................... 17

Fig. 2.3.3 Main Board ................................................................................................................ 18

Fig. 2.3.4 CPU Board ................................................................................................................ 19

2.4 Typical Wiring Diagram ............................................................................................................. 20

Fig. 2.4 Typical Wiring Diagram ................................................................................................ 20

Chapter 3: Start-Up ....................................................................................................................... 21

3.1 Introduction ............................................................................................................................... 21

3.2 Acceleration Adjustments .......................................................................................................... 21

3.3 Deceleration Adjustments ......................................................................................................... 22

3.4 Sequence of Normal Operation ................................................................................................. 23

3.5 Emergency Bypass Operation .................................................................................................. 25

Chapter 4: User Interface and Menu Navigation ......................................................................... 26

4.1 Keypad/Operator Interface ........................................................................................................ 26

4.1.1 Keypad Operator designations and functions ......................................................................... 26

4.2 Menu Navigation ....................................................................................................................... 27

4.2.1 Password Access ................................................................................................................... 28

4.2.2 Changing Setpoints ................................................................................................................ 28

Chapter 5: Setpoint Programming ............................................................................................... 29

5 .1 Setpoints Page List ............................................................................................................. 29-35

5.1.1 Basic Configuration (Setpoint Page 1) .................................................................................. 29

5.1.2 Starter Configuration (Setpoint Page 2) ................................................................................ 29

5.1.3 Phase and Ground Settings (Setpoint Page 3) ...................................................................... 30

5.1.4 Relay Assignments (Setpoint Page 4) ................................................................................... 31

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5.1.5 Relay Configuration (Setpoint Page 5) .................................................................................. 32

5.1.6 User I/O Configuration (Setpoint Page 6) .............................................................................. 32

5.1.7 Custom Acceleration Curve (Setpoint Page 7) ...................................................................... 33

5.1.8 Overload Curve Configuration (Setpoint Page 8) .................................................................. 33

5.1.9 RTD Option Configuration (Setpoint Page 9) ........................................................................ 34

5.1.10 RTD Password Level Configuration (Setpoint Page 10) ...................................................... 35

5.1.11 Communication (Setpoint Page 11) ..................................................................................... 35

5.1.12 System (Setpoint Page 12) ................................................................................................. 35

5.1.13 Calibration and Service (Setpoint Page 13) ......................................................................... 35

5.2 Setpoints Menu and Parameter Explanation ........................................................................ 36-65

SP.1 Basic Configuration ................................................................................................................ 36

SP.2 Starter Configuration ......................................................................................................... 37-42

Fig. SP2.3 Example of Switching from Jog to Start Ramp #1 Type: Voltage ............................. 39

Fig. SP2.4 Power Ramp ............................................................................................................ 41

SP.3 Phase & Ground Settings .................................................................................................. 43-46

Fig. SP3.5 Overcurrent Trip Delay Graph .................................................................................. 43

SP.4 Relay Assignment ............................................................................................................. 47-42

SP.5 Relay Configuration ................................................................................................................ 48

SP.6 User I/O Configuration....................................................................................................... 49-51

SP.7 Custom Acceleration Curve ............................................................................................... 52-54

SP.8 Overload Curve Configuration ........................................................................................... 55-57

SP.9 RTD Option Configuration ................................................................................................. 58-59

SP.10 Set Password ....................................................................................................................... 60

SP.11 Communications .................................................................................................................. 60

SP.12 System Setpoints ............................................................................................................ 61-62

SP.13 Calibration & Service ............................................................................................................ 63

Chapter 6: Metering Pages ........................................................................................................... 64

6.1 Metering Page List .................................................................................................................... 64

6.1.1 Metering Menu & Data (Metering Page 1) ............................................................................. 64

6.1.2 Metering (Metering Page 2) .................................................................................................. 64

6.1.3 RTD Option Values (Metering Page 3) .................................................................................. 64

6.1.4 Status (Metering Page 4) ...................................................................................................... 64

6.1.5 Event Recorder (Metering Page 5) ........................................................................................ 65

6.1.6 Last Trip (Metering Page 6) .................................................................................................. 65

6.1.7 Statistics (Metering Page 7) ................................................................................................. 65

6.2 Metering Menu and Explanation ................................................................................................ 66

MP.1 Metering Data ........................................................................................................................ 67

MP.2 Metering ................................................................................................................................ 68

MP.3 RTD Values ........................................................................................................................... 69

MP.4 Status .................................................................................................................................... 70

MP.5 Event Recorder – 60 Events .................................................................................................. 71

MP.6 Last Trip ................................................................................................................................ 72

MP.7 Statistics ................................................................................................................................ 73

Chapter 7: Maintenance and Troubleshooting ........................................................................... 74

7.1 Failure Analysis ................................................................................................................... 74-76

7.1.1 SCR Testing Procedure ......................................................................................................... 76

GENERAL

Unit Running Overload Capacity
(Percent of motor FLA)

125% - Continuous
500% - 30 seconds
1 Cycle: Up to 14x FLA (Internally protected by the programmable short circuit)

Frequency

50 or 60Hz, +2Hz hardware selectable

Power Circuit

6 SCRs, 12 SCRs, 18 SCRs (Model dependent)

SCR Peak Inverse Voltage
Ratings

6500V - 19500V (Model dependent see Table 1) Note: Contact Factory

Phase Insensitivity

User selectable phase sequence detection

Transient Voltage Protection

RC snubber dv/dt networks (One per inverse pair of SCRs)

Ambient Condition Design

Enclosed units: 0° to 40°C (32° to 104°F) (optional - 20° to 50° C with heaters)
5 - 95% relative humidity
0 - 3300 ft. (1000m) above sea level without de-rating
(Ratings for ambient conditions external to unit)

Control

2 or 3 wire 120VAC (Customer supplied)

Auxiliary Contacts

Multiple: Form C (Contacts), rated 5 Amps, 240VAC max.

8 Relays (4 programmable): Form C contacts

Fault Indicator: Form C contacts

BIL Rating

2300V - 7200V 60KV

Approvals

UL recognized, Canadian UL (cUL) recognized

ADVANCED MOTOR PROTECTION

Two Stage Electronic
Overload Curves

Starting: Programmable for Class 5 through 30
Run: Programmable for Class 5 through 30 when "At-Speed" is detected.

Overload Reset

Manual

Retentive Thermal Memory

Overload circuit retains thermal condition of the motor regardless of control
power status. Unit uses real time clock to adjust for off time.

Dynamic Reset Capacity

Overload will not reset until thermal capacity available in the motor is sufficient for
a successful restart. Starter learns and retains this information by monitoring
previous successful starts.

Phase Current Imbalance
Protection

Imbalance Trip Level: 5 - 30% current between any two phases
Imbalance Trip Delay: 1 -20 seconds

Over Current Protection
(Electronic Shear Pin)

Trip Level: 100 - 300% of motor FLA
Trip Delay: 1 - 20 seconds

Load Loss Trip Protection

Under Current Trip Level: 10 -90 % of motor FLA
Under Current Trip Delay: 1 - 60 seconds

Coast Down (Back Spin)
Lockout Timer

Coast Down Time Range: 1 - 60 minutes

Starts-per-hour Lockout Timer

Range: 1 - 6 successful starts per hour
Time between starts: 1 - 60 minutes between start attempts

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Chapter 1 - Introduction

This chapter is an introduction to the Reduced Voltage Solid State Soft Starter for medium voltage AC motors. It is highly
recommended that users read this section thoroughly to become familiar with the basic configuration, operation and
features before applying the Soft Starter.

1.1 Overview

The standard Soft Starter is an SCR-based controller designed for the starting, protection and control of AC medium
voltage motors. It contains SCR stack assemblies, fiber optic connections, and low voltage control circuitry ready to
be interfaced with an enclosure and the necessary equipment to create a complete a Class E2 medium voltage
motor Soft Starter.

1.2 Specifications

Motortronics Inc. Page 1

PROGAMMABLE OUTPUTS

Type / Rating

Form C (SPDT), Rated 5 amps 240 VAC max, (1200 VA)

Run Indication

Programmable

At Speed Indication

Programmable

Acceleration Adjustments

Programmable Ramp Types: Voltage or Current Ramp (VR or CR)
Starting Torque: 0 - 100% of line voltage (VR) or 0 - 600% of motor FLA (CR)
Ramp Time: 1 to 120 seconds
Current Limit: 200 - 500% (VR or CR)
Power Ramp: 0 – 300%

Dual Ramp Settings

4 Options: VR1+VR2; VR1+CR2; CR1+CR2; CR1+VR2
Dual Ramp Control: Ramp 1 = Default
Ramp 2 = selectable via dry contact input

Deceleration Adjustments

Begin Decel Level: 80 - 100% of line voltage
Stop Level: 0 to 1% less than Begin Decel Level
Decel Time: 1 - 60 seconds

Jog Settings

Voltage Jog: 5 - 75%

Kick Start Settings

Kick Voltage: 10 - 100%
Kick Time: 0.1 - 2 seconds

Fault Display

Shorted SCR, Phase Loss, Shunt Trip, Phase Imbalance Trip, Overload,
Overtemp, Overcurrent, Short Circuit, Load Loss, Undervoltage or Any Trip

Lockout Display

Coast Down Time, Starts Per Hour, Time Between Starts, and Any Lockout

EVENT HISTORY

Up to 60 Events

Data includes cause of event, time, date, voltage, power factor and current for
each phase and ground fault current at time of event

METERING FUNCTIONS

Motor Load

Percent of FLA

Current Data

A, B, C Phase Current, Avg Current, Ground Fault (Option)

Thermal Data

Remaining thermal register; thermal capacity to start

Start Data

Avg Start Time, Avg Start Current, Measured Capacity to start, time since last
start.

RTD Data (Option)

Temperature readings from up to 12 RTDs (6 stator RTDs)

Voltage Metering

kW, kVAR, PF, kWH

SERIAL COMMUNICATIONS

Protocol

Modbus RTU

Signal

RS-485, RS-422 or RS232

Network

Up to 247 devices per mode

Functionality

Full operation, status view, and programming via communications port

OPERATOR INTERFACE

LCD Readout

Alpha numeric LCD display

Keypad

8 function keys with tactile feedback

Status Indicators

12 LEDs include Power, Run, Alarm, Trip, Aux Relays

Remote Mount Capability

Up to 1000 circuit-feet from chassis (Use twisted, shielded wire & power source)

CLOCK and MEMORY

Operating Memory

SRAM loaded from F-RAM at initialization

Factory Default Storage

Flash Memory

Customer Settings and Status

Non-volatile F-RAM, no battery backup necessary

Real Time Clock

Lithium ion battery for clock memory only

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SEC.

Table or Drawing

Page

Number

SEC.

Table or Drawing

Page

Number

1.2

Specifications

1 - 2

5.2

Setpoint Page 7 Displays –
Custom Acceleration Curve

52-54

1.4

Design Features
(Unit PIV Ratings)

4

Setpoint Page 8 Displays –
Overload Curve Configuration

55-57

1.9
&

4.1

Electronics
(Keypad Operator Interface)

8 & 26

Setpoint Page 9 Displays –
RTD Option Configuration

58-59

2.2

TCB Board Layout and
Connections

10

Setpoint Page 10 Displays –
Set Password

60

TB1, TB2 & TB3 Description

12

Setpoint Page 11 Displays -
Communications

60

TB4, TB5 & TB6 Description

13

Setpoint Page 12 Displays –
System Setpoints

61-62

TB7 & TB8 Description

14

Setpoint Page 13 Displays –
Calibration & Service

63

Jumper Selections

15

6.1

Metering Page List

54-65

Switch Settings

15

6.2

Metering Menu

66

LED Indicators

16

Metering Page 1 Displays - Metering Data

67

2.3

Optional RTD Board

17

Metering Page 2 Displays - Metering

68

Communications Board
Layout & Connections: RS485
and RS422

17

Metering Page 3 Displays - RTD Values

69

Power Board & Connections

18

Metering Page 4 Displays - Status

70

CPU Board Layout &
Connections

19

Metering Page 5 Displays - Event Recorder

71

2.4

Typical Wiring Diagram

20

3.2

Acceleration Adjustments

21

Metering Page 6 Displays - Last Trip

72

3.3

Deceleration Adjustments

22

Metering Page 7 Displays - Statistics

73

3.4

Sequence of Operation

23

7.1

Failure Analysis & Troubleshooting

74-76

4.2

Menu Navigation

27

7.1

SCR Testing Procedure

76

Changing Setpoints Example

25

NOTES-

5.1

Setpoints Page List

29 – 35

5.2

Setpoint Menu & Parameter
Explanation

36-65

Setpoint Page 1 Displays ­Basic Configuration

36

Overload Class Trip Curves

37

Setpoint Page 2 Displays ­Starter Configuration

37-42

Jog/Voltage Ramp

39

Setpoint Page 3 Displays ­Phase & Ground Settings

41

Overcurrent Trip Delay Graph

43

Setpoint Page 4 Displays ­Relay Assignment

47-42

Setpoint Page 5 Displays ­Relay Configuration

48

Setpoint Page 6 Displays ­User I/O Configuration

49-51

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1.3 Reference chart

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200 & 400 Amps Units

600 Amps Units

Voltage

Series

Devices

Total

Number

of

SCRs

PIV Rating

Voltage

Series

Devices

Total

Number
of SCRs

PIV Rating

2300 V

0 6 6500 V

2300 V

2

12

9000 V

3300 / 4160 V

2

12

9000/13000 V

3300 / 4160 V

4

24

9000/18000 V

6000 - 7200 V

3

18

19500 V

6000 - 7200 V

4

36

18000 V

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1.4 Design Features

The standard Soft Start panel has the following features:

 SCR Power Modules: For each phase, the SCRs are arranged in inverse parallel pairs and series strings as

indicated in Table1 below to facilitate sufficient Peak Inverse Voltage ratings for the application

 RC Snubber Networks: Provide Transient Voltage Protection for SCR Power Modules in each phase to avoid dv/dt

damage.

 Firing Circuit: The SCRs are gated (turned on) using a Sustained Pulse Firing Circuit. This circuitry is isolated from

the control voltage by means of fiber optics.

Table 1 Unit PIV Ratings

1.5 Theory of Operation

The Soft Starter is CPU controlled, using a microprocessor based protection and control system for the motor and starter
assembly. The CPU uses Phase Angle Firing control of the SCRs to apply a reduced voltage to the motor, and then
slowly and gently increases torque using voltage and current control until the motor accelerates to full speed. This starting
method lowers the starting current of the motor, reducing electrical stresses on the power system and motor. It also
reduces peak starting torque stresses on both the motor and mechanical load, promoting longer service life and less
downtime.

1.5.1 Acceleration:

The soft starter comes standard with several methods of accelerating the motor so that it can be programmed to match
almost any industrial AC motor application. The factory default setting applies a Voltage Ramp with Current Limit as this
has been proven to be the most reliable starting method for the vast majority of applications. Using this starting method,
the Initial Voltage setting applies just enough voltage to cause the motor shaft to begin to turn. This voltage is then
gradually increased over the "Ramp Time" setting, until one of two things happen: the motor accelerates to full speed, or
the Ramp Time expires and the Current Limit setting is reached.

If the motor accelerates to full speed before the ramp time has expired, an automatic Anti- Oscillation feature will override
the remaining ramp time and full voltage will be applied. This will prevent any surging or pulsation in the motor torque,
which might otherwise occur If the motor has not reached full speed at the end of the ramp time setting, the current limit
setting will proportionally regulate the maximum output torque. CPU algorithms provide protection against a stall condition,
an overload condition or excessive acceleration time.

The Current Limit feature is provided to accommodate installations where there is limited power available (For example,
on-site generator power or utility lines with limited capacity). The torque is increased until the motor current reaches the
pre-set Current Limit value at which point it is then held. Current Limit overrides the ramp time setting so if the motor has
not accelerated to full speed under the Current Limit setting, the current remains limited for as long as it takes the motor to
accelerate to full speed.

When the motor reaches full speed and the current drops to running levels, the soft starter detects an At-Speed condition
and automatically closes the Bypass Contactor. The Bypass Contactor serves to shunt power around the SCR stack
assemblies to prevent heat build-up in the starter enclosure. At this point, the motor is operating at full voltage, speed and
power.

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Other starting methods available in the soft starter are:

• Current Ramp: Uses a closed loop current feedback algorithm to provide a linear current increase up to a Maximum

Current level.

• Constant Current: current is immediately increased to the Current Limit point and held there until the motor reaches

full speed.

• Power (KW) Ramp: Uses a True RMS KW feedback PID loop to provide a linear increase in True RMS motor power

to a maximum set KW value.

• Custom Curve: Gives the user the ability to plot torque and time points on a graph. The soft starter will then

accelerate the motor following these points.

• Tachometer Feedback Ramp: uses a closed loop speed follower method monitoring a tachometer input signal from
the motor or load shaft to provide a linear RPM acceleration.

1.5.2 Deceleration: The soft starter provides the user with the option of having the load coast to a stop or controlling the

deceleration by slowly reducing the voltage to the motor upon initiating a stop command. The Decel feature is the
opposite of DC injection braking in that the motor will actually take longer to come to a stop than if allowed to coast to a
stop. The most common application for the Decel feature is pumping applications where a controlled stop prevents water
hammer and mechanical damage to the system.

1.6 General Protection

The Soft Starter is provided with a built-in motor protection relay that can be programmed for primary protection of the
motor / load system. Operation of the Soft Starter can be divided into 4 modes; Ready, Start, Run and Stop.

1.6.1. Ready Mode: In this mode, control and line power are applied and the Starter is ready for a start command.

Protection during this mode includes the monitoring of current for leakage through multiple shorted SCRs or
welded contacts on the Bypass Contactor. Other protection features in effect are:

• Starter Power Pole Temperature

• Shorted SCR

• Blown Fuse Indication

• Phase Reversal (if enabled)

• Line Frequency Trip Window

• External Input Faults (Digital Input Faults are active in all modes)

Note: The “Programming Mode” can only be entered from the Ready Mode. Any attempt to enter data while the motor is
starting or running will be blocked. During programming, all protection features and start command are disabled.

1.6.2 Start Mode: These additional protection functions are enabled when the Soft Starter receives a valid Start

command:

• Phase Reversal (if enabled) Phase Reversal will still be on and is not a newly activated feature when starting.

• Start Curve

• Acceleration Timer

• Phase Imbalance

• Short Circuit / Load Pre-check (Toe-in-the-Water)

• Ground Fault (Optional)

• External Input Faults

• Accumulated Starting FLA Units (I2t Protection)

• Starting Overload Protection Curve Selection

• Thermal Capacity

Note: Shorted SCR protection is no longer in effect once the soft starter goes into the Start Mode.

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1.6.3 Run Mode: The soft starter enters the Run Mode when it reaches full output voltage and the motor current drops

below the FLA setting (motor nameplate FLA plus service factor) for a pre-determined period of time. During the Run
Mode these additional protection features are enabled:

• Running Overload Protection Curve Selection

• Phase Loss

• Under Current / Load Loss

• Over Current / Electronic Shear Pin (Jam Protection)

• External Input Faults

1.6.4 Stop Mode: Once a Stop command has been given, the protection features change depending on which Stop Mode

is selected.

• Decel Mode: Retains all protection features of the Run Mode. At the end of Decel, the motor will be stopped and the
protection features change as indicated below.

• Coast-To-Stop Mode: Power is immediately removed from the motor and the Soft Starter returns to the Ready Mode.

• Additional protection features activated when the stop command is given include:

o Coast-Down / Back Spin Timer
o Starts-per-Hour
o Time between Starts
o External Input Faults

1.7 Thermal Overload Protection

The Soft Starter plays an important role in the protection of your motor in that it monitors the motor for excessive thermal

conditions due to starting, running and ambient conditions. The soft starter has a Dynamic Thermal Register system in the
CPU that provides a mathematical representation of the thermal condition of the motor.

This thermal information is retained in memory and is monitored for excesses in both value and rate of change. Inputs are
derived from current values, imbalances and (optional) RTD measurements making it dynamic to all processes involving
the motor. The Soft Starter monitors these conditions separately during the Start and Run modes to provide proper
thermal protection at all times.

1.7.1 Start Mode overload protection is selectable using one of three methods:

• Basic Protection: I2t data is accumulated and plotted based on an Overload Curve selected in programming. This is
programmed per NEMA Class 5-30 standard curves and is based on the Locked Rotor Current (from the motor
nameplate) as programmed into the Soft Starter.

• Measured Start Capacity: The user enters a measured amount of thermal capacity from a pre-selected successful
start as a set point to the Thermal Register for the soft starter to follow.

• Learned Curve Protection: The user sets the soft starter to the “LEARN” mode and starts the motor under normal
starting conditions. The CPU then samples and records 100 data points during the start curve, analyzes them and
creates a graphical representation in memory. The soft starter is then switched to Curve Follow protection mode and
monitors motor performance against this curve. This feature is especially useful in initial commissioning tests to record
a base line performance sample (In this case, it is not necessarily used for motor protection).

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1.7.2 Run Mode overload protection is initiated when the soft starter determines that the motor is At-Speed. Overload

Protection is initiated when the motor RMS current rises above a “pick-up point” (as determined by the motor nameplate
FLA and service factor). Run mode protection is provided by the CPU monitoring the Dynamic Thermal Register. Data for
the Dynamic Thermal Register is accumulated from I2t calculations and cooling rates. A trip occurs when the register
reaches 100% as determined by the selected Overload Protection Curve (NEMA Class 5-30 standard curves) and is
based on the programmed Locked Rotor Current indicated on the motor nameplate. The Dynamic Thermal Register is
altered, or “biased”, by the following conditions:

• Current Imbalance will bias the register higher due to additional motor heating as a result of a line current imbalance
condition.

• Normal Cooling is provided when the motor current drops below the overload pick-up point or the motor is off line.
The Cooling rate is lower for motors that are off-line (such as after a trip) since cooling fans are also inoperative.

• RTD Input (Requires the optional RTD monitor card) provides a separate means of motor protection based on actual
temperatures measurements inside the motor. It runs independently of the Thermal Register Model and does not
provide input to, or bias that model.

• Dynamic Reset is another feature that adds reliability and consistency to the performance of the soft starter. If a
motor overload condition occurs and the Overload protection trips, it cannot be reset until sufficient cool down time
has elapsed. This cool down time is determined by the "Learned Thermal Capacity" required to start the motor which
must be regained before the overload can be reset. This ensures sufficient thermal capacity for a successful restart of
the motor.

• Retentive Memory provides continuous overload protection and true thermal modeling by means of a running back
up of the thermal register even if power is lost. Upon restoration of power, the soft starter will read the Real Time
Clock, then recalculate and restore the thermal register to what it should be, given the elapsed time and the cool down
rate of the motor.

• Learned Reset Capacity is a feature that is unique to the Soft Starter. By sampling the amount of thermal capacity
used in the previous three successful starts, the starter will not allow a reset until a sufficient amount of thermal
capacity has been regained in the motor. This prevents nuisance tripping and insures that unsuccessful start attempts
(which would otherwise use up the starts-per-hour capacity of the motor) are not counted.

1.8 Firing Circuit

The SCR gate firing circuit is critical to the performance and stability of the system. The firing circuit includes several
unique features which enhance the ruggedness, noise immunity and flexibility for maximized performance. These features
include:

• Auto Synchronizing of the gate timing pulses match each phase firing angle to their respective phases. The Soft
Starter actively tracks minor shifts in the line frequency avoiding nuisance tripping that may happen with conventional
gate firing systems. This is especially useful on portable or backup generator supplies, allowing the soft starter to be
used confidently in applications that have unstable power.

• Sustained Pulse firing keeps the firing signal active for 270 electrical degrees ensuring that the DC gate pulse forces
the SCR to fire even if line noise is present. This provides the Soft Starter with superior noise immunity and protects
against misfiring, enhancing the soft starter system stability.

• Closed Loop Firing Control is a method of balancing the SCR firing pattern. The CPU uses feedback signals from
the output current and voltage providing to provide smooth output preventing imbalances during ramping which
prevents unnecessary motor heating.

• Transformer Isolation of SCR firing information and signals prevents interference from line noise and EMI/RFI that
may be present. Three phase isolation transformers provide potential measurement, firing board timing while
providing isolation from the line voltage. High isolation Ring Transformers are used to step the 120v control voltage
down to 28VAC for the Sustained Pulse firing circuit, providing further isolation for the SCR gates.

• Fiber Optic Isolation is provided for all gate drive and current feedback signal interfaces between the Medium and
Low Voltage systems.

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ENTERRESETMENU

POWER
RUN

ALARM

TRIP

1

2

3

4

5

6

7

8

AUX. RELAYS

HELP

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1.9 Electronics

The Soft Starter electronic systems are divided into two categories; Low Voltage and Medium Voltage and are based on
where they are located in the Starter structure.

1.9.1 Low Voltage electronics include the Keypad Operator Interface, the CPU and Main Power PC boards which are

located in an isolated Low Voltage compartment of the enclosure.

• Keypad Operator Interface is a 2 line x 20 character LCD display with back-lighting for low ambient light conditions.
The display reads out in truncated English and can show multiple data points in each screen. Twelve LED indicators
are included which show the status of, Power, RUN, ALARM, TRIP and the 8 AUX RELAYS. The Operator
communicates with the CPU board via a serial cable link and can be remotely located up to 1000ft. from the starter.

FIG. 1.9 shows the Keypad Operator Interface.

FIG. 1.9 Keypad Operator Interface.

• CPU Board is where the microprocessor and communications co-processor are located. It is attached to the main

Power board. The CPU determines operating functions, stores user programming, acts upon feedback signals for
faults, and calculates metering and historical data. The board communicates with the Keypad Operator Interface
via a serial link cable. Analog and Digital I/O are also located on the CPU board. (See FIG. 2.3.4)

• Main Board also referred to as the Firing Board, contains the Auxiliary I/O relays and interfaces to the TCB board

(see below) for user interface. This board generates all firing signals for the SCR stacks and receives feedback
signals which are isolated via fiber optics. The board also provides signal conditioning in preparation for analog to
digital conversion. (See FIG. 2.3.3)

Motortronics Inc. Page 8

HAZARDOUS VOLTAGE

Disconnect all power supplying this equipment
prior to working on it.

Failure to follow this instruction will result in
death or serious injury.

DANGER

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1.9.2 Control Electronics are located in the Medium Voltage section of the soft starter. They include the TCB, Gate Drive

and Temp / CT boards.

• TCB (Terminal and Control Board) is the user connection interface board. This board contains the user terminal
blocks, output relays (duplicated), inputs and control power connections. It also contains additional timed relays for
interfacing with Power Factor Correction contactors (if used) and other external devices. Please note Power Factor
Capacitor warnings in Section 2.1.; also see FIG. 2.2.1.

• Gate Drive Boards are located directly on the SCR stacks. These boards connect to the Main Power board via fiber
optic cables. They amplify the gate pulse signals with power from the Ring Transformers to create the Sustained
Pulse Firing of the SCRs. There is one Gate Drive board for each pair of SCRs in each stack.

• Temp / CT Boards are attached to the Gate Drive boards on the SCR stacks and provide the heat sink Temperature
and line current signals back to the Main Power Board via fiber optic cables.

• MOV Boards are attached to standoffs mounted on the SCR heat sinks and are mounted directly below the Gate
Drive boards. The MOV boards are used to protect the SCRs from over voltage.

• DV/DT Boards are also attached to standoffs mounted on the SCR heat sinks and are mounted below the MOV

boards. The DV/DT boards are used to mitigate voltage transients across the stack assemblies.

Motortronics Inc. Page 9

HAZARDOUS VOLTAGE

Disconnect all power supplying this equipment
prior to working on it.

Failure to follow this instruction will result in
death or serious injury.

SCR DAMAGE

Do not connect (PFC) capacitors to the load
side of the unit.

Doing so will cause DI/DT damage to the
SCRs when energized.

!

CAUTION

DANGER

!

WARNING

SAFETY HAZARD

Do not bypass electrical or mechanical interlocks.

Failure to follow this instruction will cause severe
equipment damage, serious injury or death.

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Chapter 2 – Connection

2.1 Warnings

• Do not service this equipment with voltage applied! The unit can
be the source of fatal electric shock! To avoid shock hazard,
disconnect main power and control power before working on the unit.
Warning labels must be attached to terminals, enclosure and control
panel to meet local codes observing Lock Out, Tag Out procedures.

• Do not connect (PFC) capacitors or surge capacitors to the load
side (motor side) of the unit. This will cause di/dt damage to the

SCRs when they are turned on and will void the warranty on this
product. Capacitors can only be connected to the load side of the
starter through the use of an isolating contactor which is closed after
the soft starting sequence has been completed or when di/dt limiting
inductors are factory installed.

• Avoid connecting capacitors to the input side of the unit. If you
cannot avoid using capacitors across the power lines, they must be
located as far upstream as possible of the input line contactor. In this
situation, an optional power factor correction (PFC) capacitor contactor
should be specified. For additional information and specifications or
when di/dt limiting inductors are factory installed, please contact the
factory.

• Never interchange the input and output power connections on the
unit. This will cause excessive voltage to the control circuit logic.

• For bus protection, it is strongly recommended to use non-gap
MOV Type lightning arrestors in areas where lightning is a significant problem. The arrestors should be

mounted on the nearest utility pole at the Station or optionally included with the unit at the time of order.

• Medium Voltage cables can have significant capacitance values by design which can elevate Di/Dt thru the
SCRs to unsafe levels. Compensating inductors can limit these values to safe levels. Contact the factory if you need
more information on this subject.

Motortronics Inc. Page 10

2

3

4

5

6

7

8

9

10

1

2

3

4

5

6

7

8

9

10

1

2

3

4

5

6

7

1

2

3

4

5

6

7

1

8

9

10

11

12

TB4

Time Delay

NCC NO NCC NO

P.F.C. CAP

NCC NO NCC NO

2

3

4

5

6

7

1

8

9

10

11

12

TB3

Lock Out

NCC NO NCC NO

Fault

NCC NO NCC NO

2

3

4

5

6

7

8

9

10

TB2

2

3

4

5

6

7

1

8

9

10

11

TB1

CNO C ACNO NC

NOAC NC

1

Emergency Bypass
Switch Input

Relay changes state
when the Emergency
Bypass Switch is closed.

Control Power Output
(120 VAC @ 200VA)

Normally closed dry contact input, that
when opened will initiate an Emergency
stop to the system

Relays Operate to indicate
a Blown Fuse or that the
Disconnect is open

Relays Operates (with a
time delay) when the
Start Contact is initiated.

Relays Operate to pull in an
Isolated Contactor to
activate Power Factor
Correction Capacitors

Relays Operate when any
Fault condition occurs

NCNC C CC NC

NONO AC NC

AC

C

12

Optional Interlock (Factory installed Jumpers)

Relay Operates on

immediate Start / Stop

Stop

Maintain

Contact

Start

120 VAC

Control Input Power

N

N

N

N

120 VAC Input Power

Start Input

Fuse Blown Input

Dual Ramp Input

Main and CPU Circuit Board

Bypass Status Input

TB6

TB7

TB8

NC

Run Contacts

(AUX 3) Status.

Fault (AUX 1)

Status.

At Speed (AUX 4)

Status.

To TCB Board

Blown Fuse and / or Disconnect
Interlock N.O. dry contact Input.

At Speed N.C. dry contact Input

(Factory wired)

External Overload Protection
Device N.C dry contact Input.

Energizes / De-energizes

the Bypass Contactor Coil

Energizes / De-energizes

the Inline Isolation

Contactor Coil

Red LED

Red LED

FAULT

FUSE

Green LED

DELAYED

START

Green LED

PFC

TIMED OUT

Green LED

DELAYED

TIMED OUT

7 6 5

4 3

2 1

PFC

7 6 5

4 3

2 1

AUX

7 6 5

4 3

2 1

START

DLY-C

AUX-C

PFC-C

Jumpers

F1

F2

F3

JP1

Remove JP1 for
electronic Motor
overload protection
During emergency
bypass operation.

SW1

ON OFF

DUAL ADJ

F1 – Control fuse for TB1 1-9
Part No. ACG1A250AC or equiv.
F2 – Contactor and relay output fuse.
Part No. ACG4A250AC or equiv.
F3 – TB2 terminal 6 (120VAC Input)

Part No. ACG4A250AC or equiv.

2 or 3 Wire Control

Momentary or

Maintained Start /

Stop Switching

supplied by customer

FIG. 2.2.1 TCB Terminal and Control Board

SW3

SW4

SW5

7 6 5

4 3

2 1

ON

64

32

16 8 4

2

1

Switch position value;

Ex. Position 1+2+3: 1+2+4 = 7

Postion

Value

X1

X3

X5

Power

Supply

POWER

Green LED

EMERGENCY

BYPASS

Green LED

Green LED

Green LED

AUX BYPASS

AT SPEED

2

1

NEUT.

LINE

PERM

PFC

3

TB5

N

120 VAC Power

L

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2.2 Control Connections - TCB (Terminal and Control Board)

2.2.1 TCB Board

The TCB board, FIG. 2.2.1 shown below, provides interconnections between the main power and CPU boards and the
customer’s control logic connections. It is a 120 VAC control board with several auxiliary dry contacts, built-in time delay
circuits and an emergency bypass function. It also controls the inline isolation and bypass contactor and provides
provisions for shutdown interlocks. (See Section 2.2.2 for terminal designations and descriptions)

Motortronics Inc. Page 11

TB1 Start / Stop Control

T

Description

1

AC

120 VAC Control Power (Line)

2 3 NC

C

Shutdown Input – Accepts customer N.C dry contact (Factory jumper installed)

4
5

NC
C

Shutdown Input – Accepts customer N.C dry contact (Factory jumper installed)

6
7
8

NC
C
NO

Terminal 6, 7 & 8;"2-wire control is connected to pins 6 & 8". Also; "For 3 wire control, connect the N.C. STOP
button to pins 6&7 and the N.O. START button to pins 7 & 8

9

AC

120 VAC Control Power (Neutral)

10
11
12

C
NO
NC

Common
Normally Open
Normally Closed, Form C Relay that changes state on Start and Stop commands

TB2 Emergency Bypass Control

T

Description

1 2 NO

C

When the N.O. contact closes the unit reverts to an electromechanical starter. When a start command is
given the unit will start the motor across the line.

3
4
5

C
NO
NC

Terminals 3, 4 and 5 is a form C output relay that changes state when the contact at TB2 pins 1 & 2 is closed

6 7 NO

NC

120 VAC @ 200VA Aux Control Power output.

8

-

Not Used

9

10

NO
NC

Normally Open
Normally Closed, "Normally closed dry contact, opens when Emergency stop is initiated.

TB3 Fault Relay Outputs

T

Description

1
2
3

C
NO
NC

(2) Form C relay output that transfer on blown fuse or disconnect open indication.

3
4
5

C
NO
NC

(2) Form C relay output that transfer on blown fuse or disconnect open indication.

7
8
9

C
NO
NC

(2) Form C relay output that transfer on any fault indication.

10
11
12

C
NO
NC

(2) Form C relay output that transfer on any fault indication.

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2.2.2 Description of Terminal Connections

Motortronics Inc. Page 12

TB4 Optional Relay Outputs

T

Description

1
2
3

C
NO
NC

2 Form C time delay Aux relay output contacts. Time delay starts when the Start commend is given.

3
4
5

C
NO
NC

7
8
9

C
NO
NC

2 Form C time delay Aux relay output contacts. Time delay starts when the "At Speed" condition is reached
ideal for controlling a PFC contactor.

10
11
12

C
NO
NC

TB5 TCB Power

T

Description

1

L

By connecting TB5 of multiple units in parallel, PFC contactors will be inhibited from closing while a unit is
soft starting. PFCs that are already on line will remain on line. The lead unit in the parallel string requires
TB5 pins 1 & 3 to be connected to the 120Vac source and neutral respectively.

2

PFC

3

N

TB6 Main and CPU Circuit Board Control Inputs

T

Description

1 2 L

N

120 Vac Control Power Input (Main & CPU Circuit)

3 4 -

-

Start Input

5 6 -

-

Fuse Blown Input

7 8 -

-

Dual Ramp Input

9

10 - -

Bypass Status Input

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2.2.2. Description of Terminal Connections - Continued

Motortronics Inc. Page 13

TB7 Main and CPU Circuit Board Control Outputs

T

Description

1
2

Run contacts (AUX3) to the TCB board. (Signal is used to hold the Main Contactor closed during deceleration)

3
4

To the TCB board indicating the status of AUX 1.

5
6

At Speed Contacts (AUX 4) used to signal the Bypass Contactor to close.

7

Not Connected / Not Used

TB8 Control Inputs and Outputs

T

Description

1
2

N.C. dry contact input from blown fuse and/or disconnect interlock.

3
4

N.C. dry contact input from an external Overload Protection device. (Required if emergency bypass is used)

5
6

N.C. dry contact input from the Bypass Contactor for at speed indication.

7
8

Output connected to the Bypass Contactor and energizes / de-energizes the Contactor. (Factory wired)

9

10

Output connected to the Inline Isolation Contactor and energizes / de-energizes the Contactor. (Factory wired)

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2.2.2 Description of Terminal Connections - Continued

Motortronics Inc. Page 14

Jumper Selection

Jumper

Time Delay

Function

DLY-C

X1

Cycles

Start Delay

This is a selectable delay period between the initiations of a Start command and when
the CPU actually receives the signal.

AUX-C

X3

Cycles

Auxiliary Start Delay
This is a selectable delay period from the initiation of a Start command.

PFC-C

X5

Cycles

PFC Contactor Delay
This is a selectable delay period between when the Bypass Contactor closes to when
the Power Factor Capacitors Contactor is activated.

JP1

N/A

Motor Protection Jumper

When this jumper is in place, the CPU will be disabled during operation in the
Emergency Bypass Mode. In this case, insure that there is an external means of
overload protection. When the jumper is removed, the CPU will be enabled to provide
electronic motor protection when operating in the Emergency Bypass Mode.

DIP Switches

Switch

Function

SW1

ON: Sets Dual Adjustment
OFF: Disabled

SW2

Not Used

SW3

Sets the
Start Delay
Value

SW3, SW4 and SW5 are 7 position DIP Switches that use binary coding to set the value
of the time delay in Cycles or Seconds as selected via jumpers X1 to X6. (See Jumper
Table.) The setting range is 0 to 127 (1+2+4+8+16+32+64). The example shown
results in a value of 7 (1+2+4)

7 6 5

4 3

2 1

ON

64

32

16 8 4

2

1

Switch position value;

Ex. Position 1+2+3: 1+2+4 = 7

Postion

Value

SW4

Sets the
AUX Start
Delay Value

SW5

Sets the
PFC
Contactor
Delay Value

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2.2.3 Description of Jumper Selections and Functions

Motortronics Inc. Page 15

LED Indicators

Function

Location

Color

Function

Fuse Blown/
Disconnect

D4

Red

ON: When a Fuse is blown and / or a Disconnect is open.

Fault

D16

Red

ON: When any Fault has occurred.

Start

D7

Yellow

ON: When a Start signal has been initiated.

PFC Timed Out

D17

Yellow

ON: When the Power Factor Correction Capacitors Contactor is energized.

Delay Timed Out

D15

Yellow

ON: When the Auxiliary Start Contacts have been energized.

+24V

D28

Green

ON: +24V supply is good.

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2.2.5 Description of LED Indicators Functions

Motortronics Inc. Page 16

12 13

24

25

36 37

48

TB1 TB2 TB3

TB4

RTD1

RTD2 RTD3 RTD4

RTD5 RTD6 RTD7

RTD8 RTD9 RTD10

RTD11 RTD12

1

Signal

Power

Compensation

Shield

Typical RTD Installation

U5

U10

U11

R49

R35

U1

U12

U7

U8

U13

U4

U9

R9

C4 C6+

C9

C7

U2

R15

C17

P1

R6

R10

C10

C11

C31

R2

Q1

Q3

R16

C18

C33

C32

C1

R7

R11

R17

C12

C19

U3

R3

C2

C13

R2

Q3

Q4

X1

C8+

C3

U6

C39

L1

C45

C38

C44

L2

C43

C37

C36

C42

1

6

TB1

TB2

J1

(RS485)

X1

(RS422)

X2

X3

1

6

X4

1

7

RS485

Customer Connections

A+ A- NC NC Shield

RS422

Factory Only

A+ A- B+ B- Shield

RCV XMIT

Install jumper X1 to insert termination resistor
for last unit in Modbus string. All other units in
the string should have the X1 jumper off

J4

Connects to the

Keypad Interface

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2.3 PCB Layout Section - THIS SECTION IS FOR REFERENCE ONLY. NO FIELD WIRING OR

CONNECTIONS ARE REQUIRED.

2.3.1 Optional RTD Board

FIG. 2.3.1 Optional RTD Board

2.3.2 RS485 / RS422 Communications Board

Note: This Board is mounted on the back of the Keypad Interface

2.3.3 Main Board

Motortronics Inc. Page 17

FIG. 2.3.2 RS485 / RS422 Communications Board

TB1

654

3

2

112

11

1098

7654

3

2

1

12

11

1098

7654

3

2

1

TB2

TB3

F1

J7

J2

1- C Phase

4- B Phase

7- A Phase

J1

J3

J4

1

1

7

7

J6

19

20

1

2

J5

19

20

1

2

X1

Test Points

Circuit Board

Ground

AI

AT

BI

BT

CI

CT

GF

C1

C2

A1

A2

B1B2

J8

1 3

1

3

1 6

C NCNO C NCNO

C

NCNO

C NCNO

C NCNO C NCNO

C NCNO C NCNO

AUX 1
(TRIP)

AUX 2

(ALARM)

AUX 3

(RUN)

AUX 4

(AT SPEED)

AUX 5 AUX 6

AUX 7

AUX 8

Factory Only

Do Not Program

Refer to Set Point Page 5 information

Relay Output Contact Rating : 240VAC @ 5A (1200VA)

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FIG. 2.3.3 Power Board

Motortronics Inc. Page 18

TB1

98

7654

3

2

1 8

7654

3

2

1

TB2

TB3

J1

1 8

1

8

7654

3

2

1

CGND1

CGND3

J3

39

40

12

J2

CGND4

CGND2

TB4

7 6 5 4 3 2 1

X3

1

3

Bat

2

J5

1

7

J4

J7

19

20

1

2

BT1

+

J6

19

20

1

2

Tach.
Input

+

_

Analog
Output #1
4 – 20 mA

+

_

+

_

Analog
Output #2
4 – 20 mA

+

_

+

_

+

_

+

_

+

_

Program

Enable

Input

NOTE: Install program jumper to enable set
point programming. Jumper must be removed
after programming or for prolonged storage to
preserve settings.

External
Input #2

Opto – isolated Inputs

TB3: Only use terminal 3 and 4, all
other terminals are for factory use.

DO NOT

CONNECT

DO NOT

CONNECT

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2.3.4 CPU Board

Motortronics Inc. Page 19

FIG. 2.3.4 CPU Board

ENTERRESETMEN U

POWER

RUN

ALARM

TRIP

1

2

3

4

5

6

7

8

AUX. RELAYS

HELP

2

3

4

5

6

7

8

9

10

1

2

3

4

5

6

7

8

9

10

1

2

3

4

5

6

7

1

2

3

4

5

6

7

1

8

9

10

11

12

TB4

Time Delay

NCC NO NCC NO

P.F.C. CAP

NCC NO NCC NO

2

3

4

5

6

7

1

8

9

10

11

12

TB3

Lock Out

NCC NO NCC NO

Fault

NCC NO NCC NO

2

3

4

5

6

7

8

9

10

TB2

2

3

4

5

6

7

1

8

9

10

11

TB1

CNO C SNO NC NON NC

1

NCNC C CC NC NONO AC NCAC C

12

Stop

Maintain
Contact

Start

N

TB6

TB7

TB8

NC

Red LED

Red LED

FAULT

FUSE

Green LED

DELAYED

START

Green LED

PFC

TIMED OUT

Green LED

DELAYED

TIMED OUT

7 65 4 3 2 1

PFC

7 65 4 3 2 1

AUX

7 65 4 3 2 1

START

DLY-C

AUX-C

PFC-C

Jumpers

F1

F2

F3

JP1

Remove JP1 for
electronic Motor
overload protection
During emergency
bypass operation.

SW1

ON OFF

DUAL ADJ

SW3

SW4

SW5

X1X3X5

Power

Supply

POWER

Green LED

EMERGENCY

BYPASS

Green LED

Green LED

Green LED

AUX BYPASS

AT SPEED

2

1

NEUT.

LINE

PERM

PFC

TB5

3

TB1

6543

2

112

111098

7654

321

12

111098

7654

321

TB2

TB3

F1

J7

J2

J1

J3

J4

1

1

7

7

J6

19

20

1

2

J5

19

20

1

2

X1

C1C2

A1A2

B1B2

J8

1 3

1

31 6

C NCNO C NCNO C NCNO C NCNO C NCNO C NCNO C NCNO C NCNO

AUX 1

(TRIP)

AUX 2

(ALARM)

AUX 3

(RUN)

AUX 4

(AT SPEED)

AUX 5 AUX 6 AUX 7

AUX 8

TB1

987654321 87654321

TB2 TB3

J1

1 8

1

8

7654

321

CGND1

CGND2

J3

39

40

12

J2

CGND4

CGND2

TB4

7 6 5 4 3 2 1

X3

1 3

Bat

2

J5

1

7

J4

J7

19 20

1 2

BT1

+

J6

19 20

1 2

12 13

24

25 36 37 48

TB1 TB2 TB3 TB4

RTD1 RTD2 RTD3 RTD4

RTD5 RTD6 RT D7 RTD8 R TD9 RTD10 R TD11 RTD12

1

U5

U10

U11

R49

R35

U1

U12

U7

U8

U13

U4

U9

R9

C4 C6+

C9

C7

U2

R15

C17

P1

R6

R10

C10

C11

C31

R2

Q1

Q3

R16

C18

C33

C32

C1

R7

R11

R17

C12

C19

U3

R3

C2

C13

R2

Q3

Q4

X1

C8+

C3

U6

C39

L1

C45

C38

C44

L2

C43

C37

C36C42

1

6

TB1 TB2

J1

(RS485)

X1

(RS422)

X2

X3

1 6

X4

1

7

(RS485)

B+ A- NC NO Shield

(RS422) Factory Only

A+ A- B+ B- Shield

RCV XMIT

Remove Jumper for last unit in Modbus string

3Ø Medium

Voltage Supply

Medium Voltage

CPT

(Optional)

Ø BØ A

Ø C

Ø A

Ø B

H1

H2

X1 X2

H1

H1H2 H2

X1 X1X2 X2

H

N

Ø A

Ø B

Ø C

120VAC

120VAC 120VAC

Located in Medium Voltage Section

199
201
180
179

Program Jumper

199

201

180
179

191

192

195

197

189

190

194

193

202
204

189

190

191

192

197

195

202

194

193

204

NOTE 1 - See FIG. 2.2.1 for TCB Board
detailed connections

NOTE 1

GROUND FAULT

BOARD

(Optional)

MVC3-GF / CT

ZERO
SEQUENCE
CT @ 0.05A

CPU BOARD

(See FIG. 2.3.4)

TCB BOARD

(See FIG. 2.2.1)

RTD BOARD

(See FIG. 2.3.1)

(Optional)

FIBER OPTIC

HARNESS

POWER BOARD

(See FIG. 2.2.3)

A+A-B+ B-

COMM BOARD
(See FIG. 2.3.2)

(Rear View of Board)

J4

RS485

Customer

Connection

6543

2

1

Ø A Ø B

Ø C

Ø A

Ø B

Ø C

START

STOP

Maintain
Contact

2-Wire or 3-Wire
Start Control Wiring

3Ø to

Power

Poles

NOTE 1

N

H

To SCR Power Section

KEYPAD INTERFACE

(See FIG. 1.9)

A+

A-

NC

NC

S

Twisted Pair

S

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2.4 Typical Wiring Diagram

FIG. 2.4 Typical Wiring Diagram

Motortronics Inc. Page 20

ACCELERATION

Starting Torque Level

Current Limit

TORQUE VOLTAGE

100 %

Acceleration Mode

Ramp Time

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Chapter 3 - Start-up

3.1 Introduction

It is best to operate the motor at its full load starting condition to achieve the proper settings. Initial settings are set to
accommodate most motor conditions. TRY INITIAL SETTINGS FIRST. See Section 5.1.2 Starter Configuration (Set Point
Page 2) to make any adjustments.

3.2 Acceleration Adjustments

The unit is set at the factory with typical starting characteristics that perform well in most applications. When the system is
ready to start, try the initial settings. If the motor does not come up to speed, increase the current limit setting. If the motor
does not start to turn as soon as desired, raise the Initial voltage adjustment. Adjustment description and procedures are
described as follows. See Section 5.1.2 Starter Configuration (Set Point Page 2) for additional Accel settings.

3.2.1 Initial Voltage

Factory Setting = 20% of line voltage
Range = 0% - 100% of line voltage

Initial voltage adjustment changes the initial starting voltage level to the motor.

3.2.2 Ramp Time

Factory Setting = 10 sec.
Range = 0 - 120 sec.

Ramp time adjustment changes the amount of time it takes to reach the current limit point or full voltage if the Current limit
point was not reached.

Note: Refer to your motor manual for the maximum number of starts per hour allowed by the manufacturer and do not
exceed the recommended number.

3.2.3 Current Limit (see FIG. 3.2.3)

Factory Setting = 350% of motor FLA
Range = 200% - 500% of motor FLA

The main function of current limit is to limit the maximum current. It may also be used to extend the ramp time if required.
The interaction between the voltage ramp and the current limit will allow the soft start to ramp the motor until the
maximum current is reached and the current limit will hold the current at that level. The current limit must be se high
enough to allow the motor to reach full speed. The factory setting of 350% is a good starting point.

Do not set the current limit too low on variable starting loads. This could cause the motor to stall and eventually
cause the overload protection to trip.

Note: If the motor does stall, refer to the motor manufacturer’s motor data for the proper cooling time.

Motortronics Inc. Page 21

FIG. 3.2.3 Current Limit