Type 1 and Type 2 coordination are ratings applied to motor starters, as per IEC standard 60947-4-1. This rating is based on the level of protection and resilience provided during a high current fault.
The differences between the two levels can be explained as follows:
A motor starter with type 1 protection is designed to protect people and equipment during a short circuit fault, but after this event it may be too damaged for further use. For example, the overload could be ruined, or the contacts may have fused. Repairs and replacement parts are usually required to get the motor starter back into working order.
A motor starter which incorporates type 2 coordination will protect people and equipment, and it will still be in working order without requiring expensive repairs and replacement parts. Type 2 incorporates minimal fusing of contacts which can be easily separated with a screwdriver. This feature means the motor starter can continue service without downtime for maintenance and repairs.
Choosing the right type
In cases where the probability of experiencing a high current short circuit fault is low, type 1 coordination is considered sufficient. Type 2 is recommended for applications where there is a significant risk of a high current short circuit fault, and applications with critical up-time.
Type 2 Requirements
DOL starters require circuit breaker, a contactor and/or thermal overload combination which has been certified to type 2 by the manufacturer. The additional cost involved is small. For Soft Starters, semiconductor fuses may also be required, and this can add to the cost and require additional cabinet space.