Technical data

7
©1995 Square D—All Rights Reserved
11/98
The circuit breaker can be equipped with a microprocessor-based, electronic control unit which
provides all the traditional protection of the universal power circuit breaker (long-time, short-time,
instantaneous and ground-fault) plus other built-in functions:
n RMS sensing (standard)
n Alarm switch (standard)
n Overcurrent trip switch (standard)
n Interchangeable rating plugs (on STR28DP, STR38SP and STR58UP)
n Thermal memory and I
2
t ramp (standard on STR 38-58 control unit)
n Defeatable instantaneous (standard on STR 38-58 control unit)
n Zone-selective interlocking for ground-fault and short-time (option)
n Current and load meter (option)
n Load-monitoring outputs (option)
n Fault indicators (option)
n Communication ability (option)
Control Units STR 18M STR 28D STR 38S STR 58U
Basic Features
Long-time (1) Setting Adjustable Adjustable Adjustable
Delay Fixed Fixed Adjustable
Short-time Pickup Adjustable Adjustable
Delay Adjustable Adjustable
Instantaneous Adjustable Adjustable Fixed (2) Adjustable (2)
Test Receptacle Standard Standard Standard
Additional Features (Options)
Ground-fault Protection (3) nn
Built-in Ammeter nn n
Fault Indicators nn
Segregated Alarm Switch n
Zone-selective Interlocking n
Load Monitoring n
Communication Outputs n
(1) Long-time pickup at 1.1 current setting.
(2) Defeatable on N1 and H1 types.
(3) Two types: residual sensing (T) or residual source ground return (W).
Control Units
06313014