Soft Starters

Soft Starter Selection Guide

A soft starter is a device used to reduce inrush current to reduce the load on a motor's electrical circuits. Inrush current is the initial surge of current into the windings that is required to overcome inertia during motor startup. A soft starter provides protection to machines with high inertia. It slowly ramps up the speed, which prevents overheating or stress on parts of the motor.

WEG Soft Starters

Types of Soft Starters

Digital

A digital soft starter (also known as a solid state starter) is the most common type of soft starter. They last the longest compared to other types of starters due to the fact that they do not have contacts that could burn out or armatures that could break. These types of starters may include digital programming or other control features.

Reduced Voltage Start

Reduced voltage starters usually use autotransformers to adjust voltage during motor starting. When the motor ramps up to full speed, the transformer will be switched out, and the motor will then run at full voltage. The autotransformer's taps (present voltage allowances) limit the voltage to 50%, 65%, or 80% of full voltage.

Part Winding Start

Part winding starters are for loads that require low starting torque, such as blowers or low inertia fans. The motor draws full voltage but only about 65% to 70% of the full current. There is no internal motor protection with part winding systems, and such protection must be combined separately.


Sizing & Applications

Sizing

The two most important specifications you need to know to size a soft starter for your motor are:

1) Supply voltage
2) Motor size in current (Amps, kW, or HP)

Other specifications to take into account:

• Connection (continuously running or externally bypassed?)
• Wired in-line or in delta?
• Ambient temperature (For every degree above 40°C, the soft starter needs to be derated by 2% of the Full Load Current.)
•Altitude (For every 100m above 1000m, the soft starter must be derated by 1% of the Full Load Current.)

Applications

Common applications for soft starters for normal duty motors include: compressors, centrifugal pumps, escalators, short conveyor belts, and bow thrusters.

Applications for motors that requiring heavy-duty starting include: mixers, long conveyor belts, crushers, mills, and stirrers. Some applications will have both a normal and heavy duty start mode. Most motors will be able to use a soft starter, except ones designed for full torque at 0 RPM.


Protections

Soft starters protect against the following:

• Motor Overload Protection
• Locked Rotor & Overcurrent
• Phase Loss
• Phase Sequence


Product Selection

Click on the model number to view price, data sheets, specifications, and other detailed information.

SSW05 - 3 Phase, 230V or 460 V Input

Model No. Motor HP Soft Starter Amps
230 V 460 V
SSW050010T2246EPZ 3 5 10
SSW050016T2246EPZ 5 10 16
SSW050023T2246EPZ 7.5 15 23
SSW050030T2246EPZ 10 20 30
SSW050045T2246EPZ 15 30 45
SSW050060T2246EPZ 20 40 60
SSW050085T2246EPZ 30 60/75 85
WEG SSW05 Soft Starter

SSW06 - 3 Phase, 230V, 460V or 575V Input

Model No. Motor HP Soft Starter Amps
230 V 460 V 575 V
SSW060010T2257ESZ 3 5 7.5 10
SSW060016T2257ESZ 5 10 15 17
SSW060023T2257ESZ 7.5 15 20 23
SSW060030T2257ESZ 10 20 30 30
SSW060045T2257ESZ 15 30 40 45
SSW060060T2257ESZ 20 40 60 60
SSW060085T2257ESZ 25/30 50/60/75 75 85
SSW060130T2257ESZ 50 100 125 130
SSW060170T2257ESZ 60 125 150 170
SSW060205T2257ESZ 75 150 200 205
SSW060255T2257ESZ 100 200 250 255
SSW060312T2257ESZ 125 250 300 312
SSW060365T2257ESZ 150 300 350 365
SSW060412T2257ESZ 150 350 450 412
SSW060480T2257ESZ 200 400 500 480
SSW060604T2257ESZ 250 500 650 604
SSW060670T2257ESZ 250 550 750 670
SSW060820T2257ESZ 350 700 850 820
SSW060950T2257ESH1Z 400 800 1050 950
SSW060950T2257ESH2Z 400 800 1050 950
SSW061100T2257ESH2Z 450 900 1200 1100
SSW061400T2257ESH2Z 550 1200 1500 1400
WEG SSW06 Soft Starter

SSW07 - 3 Phase, 220/230V, 460/480V, or 575V Input

Model No. Motor HP Soft Starter Amps
220/230 V 460/480 V 575 V
SSW070017T5SZ 5 10 15 17
SSW070024T5SZ 7.5 15 20 24
SSW070030T5SZ 10 20 30 30
SSW070045T5SZ 15 30 40 45
SSW070061T5SZ 20 50 60 61
SSW070085T5SZ 30 75 75 85
SSW070130T5SZ 50 100 125 130
SSW070171T5SZ 60 125 175 171
SSW070200T5SZ 75 150 200 200
SSW070255T5SZ 100 200 250 255
SSW070312T5SZ 125 250 300 312
SSW070365T5SZ 150 300 350 365
SSW070412T5SZ 150 350 400 412
WEG SSW07 Soft Starter

GPH2 Series

Standard version with circuit breaker, AC1, no keypad.

Model No. Model No. Soft Starter Amps
230 V Motor HP 460 V Motor HP
GPH2005QC2000 5 GPH2010QC4000 10 17
GPH2007QC2000 7.5 GPH2015QC4000 15 24
GPH2010QC2000 10 GPH2020QC4000 20 30
GPH2015QC2000 15 GPH2030QC4000 30 45
GPH2025QC2000 25 GPH2050QC4000 40/50 61
GPH2030QC2000 30 GPH2075QC4000 75 85
GPH2050QC2000 50 GPH2100QC4000 100 130
GPH2060QC2000 60 GPH2125QC4000 125 171
GPH2075QC2000 75 GPH2150QC4000 150 200
GPH2100QC2000 100 GPH2200QC4000 200 255
GPH2125QC2000 125 GPH2250QC4000 250 312
GPH2150QC2000 150 GPH2300QC4000 300 365
GPH2175QC2000 175 GPH2350QC4000 350 412

With circuit breaker, AC1, keypad on door.

Model No. Model No. Soft Starter Amps
230 V Motor HP 460 V Motor HP
GPH2005QC2001 5 GPH2010QC4001 10 17
GPH2007QC2001 7.5 GPH2015QC4001 15 24
GPH2010QC2001 10 GPH2020QC4001 20 30
GPH2015QC2001 15 GPH2030QC4001 30 45
GPH2025QC2001 25 GPH2050QC4001 40/50 61
GPH2030QC2001 30 GPH2075QC4001 75 85
GPH2050QC2001 50 GPH2100QC4001 100 130
GPH2060QC2001 60 GPH2125QC4001 125 171
GPH2075QC2001 75 GPH2150QC4001 150 200
GPH2100QC2001 100 GPH2200QC4001 200 255
GPH2125QC2001 125 GPH2250QC4001 250 312
GPH2150QC2001 150 GPH2300QC4001 300 365
GPH2175QC2001 175 GPH2350QC4001 350 412

With circuit breaker, AC3, no keypad.

Model No. Model No. Soft Starter Amps
230 V Motor HP 460 V Motor HP
GPH2005PC2000 5 GPH2010PC4000 10 17
GPH2007PC2000 7.5 GPH2015PC4000 15 24
GPH2010PC2000 10 GPH2020PC4000 20 30
GPH2015PC2000 15 GPH2030PC4000 30 45
GPH2025PC2000 25 GPH2050PC4000 40/50 61
GPH2030PC2000 30 GPH2075PC4000 75 85
GPH2050PC2000 50 GPH2100PC4000 100 130
GPH2060PC2000 60 GPH2125PC4000 125 171
GPH2075PC2000 75 GPH2150PC4000 150 200
GPH2100PC2000 100 GPH2200PC4000 200 255
GPH2125PC2000 125 GPH2250PC4000 250 312
GPH2150PC2000 150 GPH2300PC4000 300 365
GPH2175PC2000 175 GPH2350PC4000 350 412

With circuit breaker, AC3, keypad on door.

Model No. Model No. Soft Starter Amps
230 V Motor HP 460 V Motor HP
GPH2005PC2001 5 GPH2010PC4001 10 17
GPH2007PC2001 7.5 GPH2015PC4001 15 24
GPH2010PC2001 10 GPH2020PC4001 20 30
GPH2015PC2001 15 GPH2030PC4001 30 45
GPH2025PC2001 25 GPH2050PC4001 40/50 61
GPH2030PC2001 30 GPH2075PC4001 75 85
GPH2050PC2001 50 GPH2100PC4001 100 130
GPH2060PC2001 60 GPH2125PC4001 125 171
GPH2075PC2001 75 GPH2150PC4001 150 200
GPH2100PC2001 100 GPH2200PC4001 200 255
GPH2125PC2001 125 GPH2250PC4001 250 312
GPH2150PC2001 150 GPH2300PC4001 300 365
GPH2175PC2001 175 GPH2350PC4001 350 412

TPH2 Crusher Duty

Model No. Motor HP Soft Starter Amps
460 V
TPH2100KD0000 100 130
TPH2150KD0000 150 205
TPH2200KD0000 200 255
TPH2250KD0000 250 312
TPH2300KD0000 300 365
TPH2350KD0000 350 412
TPH2400KD0000 400 480
TPH2500KD0000 500 604