electrical services minimum requirement - NSW Public Works

Part 2 - Switchboards and Associated Equipment
207.12.3 Reduced Voltage Starters
Reduced voltage starters shall be of the electromagnetically operated type complying with
AS 1202 Parts 2 and 3, offering overload protection in each phase of the supply or motor
circuit and incorporating the following features.
(a) Star Delta Starter
Star-delta starters shall include:
(i) One (1) main line contactor or equivalent.
(ii) Star and Delta contactors mechanically and electrically interlocked to
prevent simultaneous operation.
(iii) One (1) triple pole overload relay, fitted to the line contactor. Where the
star-delta starter configuration is such that the overload is connected into the
motor phase winding circuit, a nameplate shall be fixed to the starter stating
the full load current of the motor phase wind, i.e. 58% of the full load line
current of the motor.
(iv) One (1) time delay relay with nominal 0-30 second adjustable time delay
period to control the star to delta switching contactors.
(v) Where closed transition type starters are indicated, suitably rated stainless
steel resistor banks, transition contactor and time delay relay shall be
provided.
(b) Auto-Transformer Starters
207.12.4 Reversing Starters
Auto-transformer starters shall be parallel, closed transition (Korndorfer
connections) type in accordance with Diagram B1, Appendix G of AS 1202, Part 3,
utilising three poles of the star contactor ("K1"), Mechanical and electrical
interlocking shall be employed between the star contactor ("K1") and the run
contactor ("K3") to prevent simultaneous closing.
Each auto-transformer starter shall include:
(i) One (1) three core auto-transformer tapped at 50%, 65% and 80% and rated
for enclosed operation. Provide Auto-transformers with insulation class 155
to AS 2768. Provide Auto-transformers suitable for a minimum of 12 starts
per hour. House each auto-transformer in its own segregated compartment.
(ii) One (1) triple pole thermal overload relay.
(iii) Star, auto-transformer and run contactors (K1, K2 and K3).
(iv) One (1) set of three embedded thermistors, complete with manual reset,
operating relays and indicators, to protect the auto-transformer.
(v) One (1) time delay relay with nominal 0 to 30 second adjustable time delay
period to control the start and run contactors.
Reversing starters shall generally comply with Clause 207.12.1 and shall include:
(i) Two (2) main line contactors, mechanically and electrically interlocked to prevent
simultaneous closure.
(ii) One (1) triple pole overload relay.
(iii) One (1) time delay relay with nominal 0 to 30 second adjustable time delay period,
to prevent plugging of the motor.
Page 48 MEW E101