Technical Specification for M.V. Soft Starter
(e.g. 6KV, 400A – update as required)
This specification defines the minimum technical requirements for the design, manufacture,
performance and testing of a Medium Voltage Electronic Soft Starter.
The purchaser may require from the supplier to show the capability of the quoted equipment
in meeting the specification and provide a reference list.
Please contact …………………………..in case any of the above requirements is unclear.
The supplier must clearly state in his quotation any deviation from the specification
Mains voltage: 6000V +10% - 15%
Nominal Current: 400A continuous
Control voltage: 230VAC
Frequency: 50Hz ± 2 Hz
Ambient temperature: 0-500C. Relative humidity: 95% non-condensive
Maximum number of starts: 2 per hour
Altitude: see level
Centrifugal Pump 3.5 MW, 6000 KV, 400 Amp,
Scope of supply
Digital, microprocessor based soft starter in IP32 cabinet, with Line & Bypass contactors and
Motor Protection Relay.
Soft starter construction shall be of a modular design. Each phase can be separately and easily
interchanged in the field, without special tools.
The soft starter shall start the motor by slowly ramping-up the voltage supplied to the motor
while limiting the current to the required level.
The manufacturer shall offer commissioning assistance and training at site.
The manufacturer shall offer spare parts required for commissioning and 5 years operation.
To ensure long term reliability and safety, each starter shall be tested for Partial Discharge
(Corona Free), according to EN50178 & HD 625.1 S1:1996 Electronic Equipment for use in
Setting & Supervision
Starter settings shall be made on a keypad and illuminated LCD. Illuminated LCD shall
have 2 lines, 16 characters each.
Display language shall be programmable: English, German, French and Spanish.
The LCD shall display motor current, fault description and statistical data including: Total
run time, Number of starts, Last start Current, Last start time duration, Description of last
trip and Total number of trips.
The LCD shall be programmable to view a full display of all parameters - for demanding
applications or display of minimum parameters - for basic applications.
The starter shall incorporate the following LEDs for quick status display: Control voltage
On, Motor Starting, Motor Running, Motor Soft Stopping, Motor Stopped, Fault).
Keys on the keypad shall be clearly marked and setting software shall have easy-to-use
Software lock, preventing parameters change shall be by an internal dip switch
Starting & Stopping
The starter shall have the following starting and stopping settings:
Initial voltage: adjust. 10-80% Un
Current Limit: adjust. 100-500% In
Ramp-up Time: adjust. 1-90 sec.
Ramp-down Time: adjust. 1-90 sec.
Pulse Start: pulse of 80% Un, without current limit, for 0.1-1 sec.
Torque Control: for linear acceleration and deceleration with selectable Torque Curves.
Current Ramp Control: Initial Current adjust. 100-400%, Ramp-up time 1-90 sec.
Pump Control: with selectable starting and stopping curves, to prevent Over Pressure and
Water Hammer. Separate settings shall be available for starting and stopping.
Dual Adjustment with two Start Stop and two FLA settings for varying loads for two speed
Motor & Starter Protection
The starter shall have the following protection:
Excessive starts with adjustable Max. Number of Starts, Time Period and Waiting Time
(time delay after exceeding maximum number of starts).
Long Start Time (Stall protection).
Electronic Shear-pin (Jam protection) to trip instantaneously (in less than 1 cycle) when
current reaches 850% FLA. An adjustable time delay shall be available for lower currents.
Electronic Overload with selectable curves.
Under Current with time delay
Ground fault current with adjustable time delay
Current imbalance, trip time will be related to motor load
Shorted SCR &
Wrong Motor Connection
External Fault – input from a N.O. contact
Bypass Contactor Open trips the starter if bypass contactor does not close after End of
No Start Signal trips the Line Contactor in case power is connected to soft starter and start
signal was not given.
Current shall be measured by soft starter’s C/T on all three phases and above protection shall operate
before and after bypass contactor closes.
Upon fault, the starter shall trip and lock in a Fault Mode, also if mains voltage disappears
(fuse blow or voltage outage).
For maximum safety, resetting shall be possible only after start signal is removed.
Resetting shall be possible either by local Reset Key or remotely by hard wire or
Auto-Reset shall be possible for Under-Voltage, Phase Loss and Under Current Faults.
Communication (one of the following protocols, will be specified later)
MODBUS RTU RS 485 half duplex, enabling Parameter settings, Control (Start/Stop, etc.)
PROFIBUS DP enabling Control (Start/Stop, etc.) and Supervision
TCP / IP Protocol
The soft starter shall incorporate a minimum of three auxiliary relays, each with 1 C/O type, rated 8A,
250V, 1800VA, with the following functions:
Immediate Relay shall operate upon start signal, with adjustable On and Off delays. The
contact shall return to original position upon Voltage Outage, Fault, Stop signal and upon
Soft stop signal – at the end of soft stopping process.
End of Acceleration Relay shall operate upon completion of starting process, with adjust. On
delay. The contact shall return to original position upon Voltage outage, Fault and upon Stop
and Soft Stop signals.
Fault Relay – shall be programmed as:
a. Fault – changes position upon Fault, returns to original position upon Reset, after fault
had been removed.
b. Fault-Fail-Safe - changes position upon control voltage connection, returns upon fault.
(Can be used for “Control Voltage Disconnected” alarm).
Special Test Mode
Full functional test of all starter circuits shall be possible by using a standard low voltage motor of about
Analogue output (when shown in the drawings)
Analog Output, relative to motors current, field selectable 0–10VDC, 0/4–20mA
Line and By-pass contactors
Line and Bypass contactors shall be vacuum type, rated 7200V, 400A minimum.
E1 Interrupting rating 40 MVA (equivalent to 4.62KA)
E2 Fuse coordination 400 MVA 45.7KA RMS, 38R max. fuse size
Withstand KA 57.8 KA-peak, 38R-fuse
Short Time Current - 1sec-7KA, 5sec-5KA, 15sec-2.6KA
Electrical life at rated current shall be not less than 0.4 x 10 6
Mechanical life shall be not less than 0.75 x 10 6
Dielectric strength 20KV, 1min.
Impulse withstand BIL 1.2 x 50 μSec, 60 KV
Max. Chopping current 0.9A
AC control voltage 240V, 50/60Hz, +10% -15%
Pick-up / Drop-out voltage 102V / 65V
The contactor shall include 2 N.O + 2 N.C auxiliary contacts, continuous current 10A/AC,
5A/DC 600VAC, Make / Brake ratings 7200 / 720VA.
Motor Protection Relays
Each starter shall incorporate a digital microprocessor based Motor Protection Relay (MPR) as a back up
protection. Upon fault that is not cleared by the soft starter, the MPR shall trip open the Line Contactor.
In case of a high current fault, above the maximum opening current of the vacuum contactor, the MPR shall
not trip open the Line Vacuum Contactor but shall let the fuses clear the fault, thereafter opening the
The MPR shall have the following protection and settings:
Maximum Start Time (Stall Protection)
Under-Current Alarm with adjustable time delay
Under Current Trip with adjustable time delay
Load Increase Alarm
Low set Over-current (overload) with adjustable time delay
High set over-current (short circuit) with adjustable time delay
Thermal Alarm (Modeling motor heating, with adjustable time to trip at 6xIn, Hot/Cold ratio, Cool
Time Factor, Stall Time factor).
Thermal Trip with adjustable time delay
Unbalance Current Alarm with adjustable time delay, calculated according to motor’s load
Unbalance Trip with adjustable time delay.
Ground Fault Alarm with adjustable time delay
Ground Fault Trip with adjustable time delay
Under Voltage with adjustable time delay
Over Voltage Alarm with adjustable time delay
Over Voltage Trip with adjustable time delay
Under Power Trip with adjustable time delay
Motor Over Temp. – Input from Thermistor PTC / NTC or RTD (Pt100), as shown in drawing
External Fault 1 (entry from a N.O. Contact)
External Fault 2 (entry from a N.O. Contact)
Serial Communication fault
Function shall be programmable, for each fault, as Disable, Alarm Only, Trip Only, Alarm & Trip.
Trip contact shall be 5A,250VAC/DC.
Reset function shall be programmable for each fault as Auto Reset, Local Reset, Remote Reset.
Settings and supervision shall be by a LCD, 2 line, 16 characters each.
Each starter shall have a separate, completely isolated, front accessible, L.V. compartment. The L.V.
Compartment shall include at least the following components:
Soft starter Control Module, with fiber option wires.
Selector Switch Local / Remote (for door mounted Start/Stop buttons or Remote by hard
Selector switch Soft Starter / DOL starting (enabling DOL starting in case of a fault in the
Three interposing relays for starters’ output relays
Holding relay when external Start / Stop push buttons are used.
All control components mounted in the L.V. compartment shall be wired to terminal blocks, which shall
be wired to Customer Terminal blocks.
Control Components on the door
The following components shall be mounted on L.V. door:
Motor Protection Relay
Start / Stop Pushbuttons
Emergency stop push button
Indication light: Line Contactor Closed, Line Contactor Open, Bypass Contactor Closed,
Remote Operation, Fault
The cabinet shall be designed and constructed according to IEC 60694 with IP 32 Protection)
with soft starter keypad mounted behind a transparent window.
All exterior and interior metal parts shall be coated and painted under the following procedure:
Procedure - all parts shall be painted before assembly.
Preparation - Alkaline wash / rinse / iron phosphates / rinse/non chrome sealer rinse / re-
circulated de-ionized water rinse and distilled de-ionised water rinse.
Painting – Air atomised electrostatic spray, Hybrid Epoxy Polyester powder paint –semi
matt. Paint thickness 0.07 mm. Thicker painting as an option.
Color shall be RAL 7032 (unless specified differently)
Baking at 180º C (355º F) minimum.
Optional field “touch-up” spray can(s), matching the enclosure color, shall be supplied.
A continuous bare copper ground bus, 5 X 50 mm, shall be provided along the entire width of the
enclosure, at the bottom.
Power Cable Entry
Cable access shall be from bottom with a minimum of 50 cm empty space for cable connections.
Control wires shall be insulated (flame retarding thermoplastic compound), flexible stranded
copper wire supported and neatly bundled.
Control wires shall be isolated from high voltage components (whenever possible) in the
power cell. Each wire shall be marked with wire tube markers, numbered according to the
Control wire terminations shall be screw-type, copper compression type, Non-insulated,
locking type, fork tongue lugs shall be provided on the current transformers. Whenever 2
wires are connected to the same terminal, they shall be crimped together.
Customer connection terminal blocks shall be located in the medium voltage section. Remote
control cables shall be from the top or bottom of the structure.
Control cable inputs and outputs shall be through removable entry plates on top or bottom of
A door switch with 2 N.O. contacts shall be mounted on the M.V. door, opened when door is opened and
wired to the Line Contactor for interlocking. All M.V. doors shall be interlocked so the no door can be
opened when H.V. persists.
PL-13 watt protected lamp shall lit when opening the H.V. door, supplied from a dedicated miniature C/B.
Cabinet Heater (When shown on the drawing)
A 60W heater with humidity control, supplied from a dedicated miniature C/B.
Exhaust fan (When shown on the drawing)
An exhaust fan, in suitable dimensions, shall be installed on top of M.V. cabinet with air inlet at bottom
with filter, supplied from a dedicated miniature C/B.
M:\Catalogs and Marketing materials\Typical Specification\HRVS-DN\M.V. soft starters.doc