Motor starting and protection

A motor starter typically consists of a contactor and an overload protection device. Both devices must be coordinated with ''short circuit'' protection devices (SCPD) in order to properly protect motors against ''short circuits''.

The SOC tool provides coordination tables for the low-voltage equipment selection, specifically tested for IE3/IE4 motor starting and protection. Essential, enhanced and advanced solutions can be selected. Selection guidance is available for various starter types as well, including Direct-on-Line, Star-Delta and softstarters with respect to voltage, ''short-circuit'' level, starting types (Normal Start, Heavy Duty), the types of coordination required (IEC type 1 or type 2), UL Combination Motor Controller type (A to F).

Selectivity, Back-up and other protection devices

Selection of the protection system of an electrical installation is fundamental to economical and functional service of the whole installation, and to helping reduce problems caused by abnormal service conditions or actual faults.

Selectivity and Back-up is typically used in installations with a main circuit breaker upstream and different downstream lines protected by their own short circuit protection device (SCPD).

If the priority of the installation is to help ensure service continuity, then Selectivity is the coordination strategy you need. Selectivity, according to IEC 60947-1, is the coordination between the operating characteristics of two or more overcurrent protection devices (switch fuses, molded case circuit breakers, miniature circuit breakers, etc.). In the event of an overcurrent within established limits, only the SCPD installed on the line affected by the fault will operate. If the overcurrent value exceeds the selectivity limit, then the upstream device could also trip.

Selectivity is Total (T on SOC tables) if the upstream SCPD won’t trip before the downstream SCPD up to its ''short circuit'' capacity. In the case of Partial selectivity, SOC tables report the maximum ''short circuit'' value for which selectivity is assured. 

If the priority of the installation is to achieve economic savings of the components, then Back-up is the desired coordination.

Back-up is the coordination between the operating characteristics of two overcurrent protection devices (switch fuses, molded case circuit breakers, miniature circuit breakers, etc) such that the upstream protection supports the trip of the downstream protection in case of a ''short circuit'' with a higher value than the ''short-circuit'' capacity of the downstream protective device. In this way, it is possible to optimize the breaking capacity of downstream protection devices and downsize them at the same time in order to save money.

It is possible to install on a line a protection device with a breaking capacity lower than the expected local ''short circuit'' current, because in case of a fault the upstream protection device helps ensure protection through operation. In this case there is no service continuity of the downstream device, since the upstream device has tripped and the ''short-circuit'' currents were above the limits (Icu) of the downstream device, which was most likely destroyed during the event. Also, other lines connected to the upstream device will be without supply after operation, although they are not directly affected by a fault.

SOC tables define the maximum value of ''short-circuit'' for which the back-up is assured between upstream and downstream SCPDs.

In the “Other devices protection” section, the SOC tool provides the maximum ''short circuit'' value for which a downstream switch disconnector is protected by the upstream SCPD in case of fault.

Select the appropriate UL component ratings

Components used within combination motor controllers are required to have individual component ratings tested and certified according to the appropriate UL Standard for that component. 

Everything you need in one place!

• Provides guidance on appropriate product selection to help enhance protection and safety.
• Reduces solution selection and design time
• Helps decrease unexpected downtime risk, such as that caused by nuisance tripping
• Provides the latest tested coordination data
• Anticipates life cycle changes of products used in all motor coordination tables
• Accesses the dedicated motor coordination tables for your country

Features

• More than 1800 tested and validated coordination tables available
• User-friendly selection and new smart search for fast coordination table configuration
• Optimized motor protection coordination tables for IE3/IE4 high-efficiency class with respect to N/H or NE/HE motor design
• Follow-up of the sales status of the products included inside the motor protection coordination tables
• Includes dedicated product ranges available in your country
• New export PDF and e-mail sharing options
• Main languages localization for interface display and PDF documentation exportation
• New help section to train all users in an easy and quick way
  

Features

• More than 1800 tested and validated coordination tables available
• User-friendly selection and new smart search for fast coordination table configuration
• Optimized motor protection coordination tables for IE3/IE4 high-efficiency class with respect to N/H or NE/HE motor design
• Follow-up of the sales status of the products included inside the motor protection coordination tables
• Includes dedicated product ranges available in your country
• New export PDF and e-mail sharing options
• Main languages localization for interface display and PDF documentation exportation