Eaton Cutler-Hammer Digitrip 3000 Instructions For Installation, Operation And Maintenance page 10

Page 4
The Digitrip 3000 Protective Relay provides five protec-
tive functions for both phase and ground protection. The
ground element is capable of a residual, an external
source ground or a zero sequence connection. If ground
protection is not desired, the ground element does not
have to be connected.
The five protective settings are:
• Inverse Time Overcurrent Pickup
• Inverse Time Overcurrent Time Multiplier
• Short Delay Pickup
• Short Delay Time
• Instantaneous Pickup
Each of the protective functions are independently pro-
grammed for various combinations to fit specific system
requirements. For protective functions not required, the
relay will allow all of the protective functions on ground
and all but the inverse time overcurrent function on phase
to be disabled. When the Digitrip 3000 is not set for an
instantaneous trip function, a true making current release
(discriminator) is available. If not desired, the discrimina-
tor can be disabled.
Fig. 1-3 Digitrip 3000 Protective Relay with DIP
Switches Shown in Upper Left (Rear View)
Digitrip 3000 Protective Relays provide greater selective
coordination potential by providing 11 different curve
shapes (Figure 1-4).
• Thermal Curves (4 shapes)
- It
2
- I t
4
- I t
- Flat
• ANSI Curves (3 shapes per ANSI C37.112)
- Moderately Inverse
- Very Inverse
- Extremely Inverse
• lEC Curves (4 shapes per IEC 255-3)
- IEC-A (Moderately Inverse)
- IEC-B (Very Inverse)
- IEC-C (Extremely Inverse)
- IEC-D (Definite Time)
The ground element of Digitrip 3000 can have a curve
shape independent of the phase element, providing for a
more versatile ground protection.
With this vast selection of Curve Shapes, Digitrip 3000
provides protection capable of coordinating with most any
existing electro-mechanical overcurrent relay or power
fuse.
A pictorial representation of characteristic curve shapes
is provided on the face of the relay for reference pur-
poses (Figure 1-1).
All Digitrip 3000 Protective Relays have zone selective
interlocking capabilities for phase and ground fault pro-
tection. Zone selective interlocking is a means by which
two or more coordinated trip devices can communicate to
alter their pre-set tripping modes to provide a faster
response for certain upstream fault conditions. The relay
is shipped with the zone selective interlocking feature dis-
abled by the use of the two jumpers on the rear mounted
terminal strip TB1 (Figure 1-5).
Digitrip 3000 Protective Relays operating parameters and
troubleshooting information are displayed on the front of
the relay, via the two display windows. This is considered
"ON DEVICE" information. In addition, all relay informa-
tion can be transmitted to a remote location via the built-
in INCOM communication system. This type of informa-
tion is referred to as "COMMUNICATED INFORMATION."
I.B. 17555C
Effective November 1999