Technical information

1.3 Sizing of the protections and of the branch

circuit components.

1.3.1 Three-phase direct starter

The reference schematic is:

Branch Circuit Protection:

the last protection against over

currents and in particular,short

circuits.

Controller: contactor

Overload protection:

protection against overloads

Internal conductors & wires

inside the panel

Terminal: interface terminal

between the panel and on the

machine

External: conductors&wires

outside the panel

Disconnect Switch: disconnect

switch on the machine for

maintenance of the motor

Motor: three/single phase

electrical motor

This means that all the components descr

ibed m ust be appro v ed b y an NRTL f or

their intended function.Any e xceptions shall be c learly indicated.

Design example:

5hp three-phase motor (3,7 kW)

480V

Once the sizing has been completed, the components shall be chosen in the case

where the motor start has to be affected following the construction criteria IEC

and UL/CSA “normal” components with double approval

•NEMA special components for North America

BRANCH CIRCUIT