Page 958 - ABB_Motor _Protection_and_Control_catalogue_20221216

13/68 ABB MOTOR PROTECTION AND CONTROL

—

Star-delta starters protected by overload relays
With AF contactors - Open type version in kit form
Switching frequency diagrams

General
Switching frequency/hour, according to acceleration time and load factor. Respect of the following conditions enables
utilization of the starter without excessive overheating of the connections or nuisance tripping of the thermal overload relay.

Thermal overload relay
Intermittent periodic duty Example:

70
Switching frequency (ops/h) 60 ta = 8 s Starting time of the motor: 7 second (use 8s curve) - Duty ratio: 63 %
ta = 5 s
means a permitted switching frequency of max. 15 operating cycles
50
per hour.
40
30
ta = 10 s
20
7 seconds acceleration, 2.5 minutes operation and 1.5 minutes rest.
ta = 20 s
10 ta = 12 s ta = 15 s This corresponds to a 4 minute operating cycle (15 starts/hr) with
0
0 10 20 30 40 50 60 70 80 90 100
Duty ratio (%)
ta: motor starting time

Electronic overload relay : please consult us

13