Effective 8/2006
Page 3
I.L. 66A7534H04
CAUTION
CONNECTING THIS TRIP UNIT TO CURRENT SEN-
SORS OTHER THAN CH TYPE-V MIGHT DAMAGE OR
DESTROY IT.
All trip unit models are microprocessor-based AC protec-
tion devices that provide true RMS current sensing for the
proper coordination with the thermal characteristics of
conductors and equipment. The primary function of this
Digitrip trip unit is circuit protection. The Digitrip analyzes
the secondary current signals from the CH Type-V 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, causing it to “open.”
In addition to the basic protection function, the Digitrip
520V and 520MCV provide modes of trip indication such
as:
•
Long Time trip (overload)
•
Short Time trip
•
Instantaneous trip
•
Ground (Earth) Fault trip
The CH Type-V current sensors provide the power to the
trip unit. As current begins to flow through the breaker, the
sensors generate a secondary current which powers the
trip unit. No auxilary power is needed to trip the circuit
breaker.
The Digitrip 520V and 520MCV trip units have 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 necessary. The short delay and ground
fault pick-up 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 Figure 1.1. The user chooses the settings
according to the needs of his application.
(See Sections
4.0 & 9.2)
1.1 Protection
The Digitrip trip system; including associated CH Type-V
current sensors, require no external control power to
operate their protection systems. They operate from
current signal levels derived through the CH Type-V current
sensors.
Status
LED will also blink at a faster rate if the Digitrip is
in a “Long Pick-up” (overload) mode.
Four red LEDs on the face of the trip units flash to indicate
the cause of trip for an automatic trip operation... i.e.:
Long Delay (overload), Short Delay, Instantaneous or
Ground (Earth) Fault. A battery, inside the rating plug
compartment of the Digitrip unit, maintains the trip indica-
tion until the
Reset/Battery Test
button is pushed. The
battery is satisfactory if its
Battery Check
LED lights
green when the
Battery Check
button is pushed
(See
Section 6).
NOTE:
The Digitrip unit provides all protection functions
independant of the status of the battery. The battery is
used only to maintain the automatic trip indication.
1.3 Installation and Removal
1.3.1 Installation of the Trip Unit
Align the Digitrip unit with the guide pins and spring clip of
the circuit breaker. Press the unit into the breaker until the
pins on the trip unit seat firmly into the connector housing
and the unit clicks into place
(see Figure 1.2).
1.3.2 Installation of the Rating Plug
Insert the rating plug into the cavity on the right-hand side
of the trip unit. Carefully align the three pins on the plug
with the sockets in the cavity. The plug should fit with a
slight insertion force.
WARNING
DO NOT CLOSE THE CIRCUIT BREAKER WHEN THE
DIGITRIP IS REMOVED OR DISCONNECTED. DAMAGE
TO ASSOCIATED CURRENT TRANSFORMERS MAY
OCCUR DUE TO AN OPEN CIRCUIT CONDITION.
THERE IS NO PROTECTION FOR THE LOAD CIRCUIT.
CAUTION
IF A RATING PLUG IS NOT INSTALLED IN THE TRIP
UNIT, THE UNIT WILL INITIATE A TRIP WHEN IT IS
ENERGIZED. IN ADDITION THE INSTANTANEOUS LED
OF THE DIGITRIP TRIP UNIT WILL LIGHT DUE TO A
MISSING OR BAD RATING PLUG.
1.2 Mode of Trip and Status Information
A green light emitting diode (LED), labeled
Unit Status
in
Figure 1.1, blinks approximately once each second to
indicate that the trip unit is operating normally. This
Unit
