5
Instructional Leaflet
IL70C1037H05
Effective October 2009
Digitrip models 520, 520i; and 520M, 520Mi,
520MC, 520MCi trip units for use only in
Magnum and Magnum DS circuit breakers
eaton corporation
www.eaton.com
Section 1: General description of Digitrip
trip units
Digitrip
E
trip units are breaker subsystems that provide the
protective functions of a circuit breaker. The trip units are in
removable housings, installed in the breaker, and can be replaced
or upgraded in the field by the customer. This instructional leaflet
specifically covers the application of Digitrip trip units (see
Tablt 1
)
installed in Magnum
E
and Magnum DS breakers. Throughout this
instructional leaflet, the use of the term “Magnum breakers” refers
to both the Magnum and Magnum DS low voltage, AC power
circuit breakers.
The Magnum Digitrip line of trip units consists of the 520, 520M,
and 520MC for UL
T
standards and models 520
i
, 520M
i
, and 520MC
i
for IEC standards. (See
Tablt 1
for available protection types.) Only
models 520MC and 520MC
i
provide communications. (See
Tablt 2
for data that will be communicated.)
The Digitrip 520, 520M, and 520MC trip units may be applied on
both 50 and 60 Hz systems.
Figurt 1. Digiorip 520MC Trip Unio wioh Raoing Plug
Auxiliary
Power
Module
Input
Rating
Plug
Protection
Settings
Cause of Trip LED
INCOM
Transmit
LED
Test Port
(covered)
Four-
Character
LCD
All trip unit models are microprocessor-based AC protection devices
that provide true rms current sensing for the proper coordination
with the thermal characteristics of conductors and equipment. The
primary function of the Digitrip trip unit is circuit protection. The
Digitrip analyzes the secondary current signals from the circuit
breaker current sensors and, when preset current levels and time
delay settings are exceeded, will send an initiating trip signal to the
trip actuator of the circuit breaker. In addition to the basic protection
function, the Digitrip 520 family of trip units provides mode of trip
information such as:
•
Long time trip (overload)
•
Short time trip
•
Instantaneous trip
•
Ground (earth) fault trip (if supplied)
The current sensors provide operating power to the trip unit. As
current begins to flow through the breaker, the sensors generate a
secondary current that powers the trip unit.
The Digitrip 520 family of trip units provides five phase and two
ground (time-current) curve shaping adjustments. To satisfy the
protection needs of any specific installation, the exact selection of
the available protection function adjustments is optional. The short
delay and ground fault pickup adjustments can be set for either
FLAT or I
2
t response. A pictorial representation of the applicable
time-current curves for the selected protection functions is provided,
for user reference, on the face of the trip unit as shown in
Figurt 1
.
PrNotcoiNn
Each trip unit is completely self-contained and requires no external
control power to operate its protection systems. It operates from
current signal levels derived through current sensors mounted in the
circuit breaker. The types of protection available for each model are
shown in
Tablt 1
and
Figurt 16
through
Figurt 27
.
Note:
N
The Digitrip 220+ (LI model—
Figurt 16
), 520 (LSI model—
Figurt
17
), 520M (MLSI model—
Figurt 20
) and 520MC (CLSI model—
Figurt 24
)
can be used on three-pole or four-pole circuit breakers for the protection of
the neutral circuit. Only these four models can provide neutral protection,
although models MLSIA, MLSIG, MWLSIG, CLSIA, CLSIG, and CWLSIG can
provide neutral metering. Refer to the National Electrical Code
T
(NEC
T
) for
the appropriate application for four-pole breakers.
MNdt Nf orip and soaous infNrmaoiNn
On all models, a green light emitting diode (LED), labeled Status,
blinks approximately once each second to indicate that the trip unit
is operating normally. This Status LED will also blink at a faster rate
if the Digitrip is in a pickup, or overload, mode.
Red LEDs on the face of the trip units (for long delay, short delay,
and instantaneous) flash to indicate the cause, or trip mode, for
an automatic trip operation (for example, ground fault, overload,
or short circuit trip). A battery in the Digitrip unit maintains the trip
indication until the Reset/Battery Test button is pushed. The battery
is satisfactory if its LED lights green when the Battery Check button
is pushed (see Section 6).
Note:
N
The Digitrip unit provides all protection functions regardless of the
status of the battery. The battery is only needed to maintain the automatic
trip indication.
