DT3000
Instruction Leaflet
I.B. 17555D
Effective: Date 07/02
Page 7
For more information visit:
www.cutler-hammer.eaton.com
Supersedes I.B. 17555C dated November 1999
TABLE 2.1 CURVE SELECTION
Curve Type
Settings
Result
Thermal
It
I
2
t
I
4
t
FLAT
Moderately Inverse
Inverse
Extremely Inverse
Definite or Fixed Time
ANSI
MOD
VERY
XTRM
Moderately Inverse
Very Inverse
Extremely Inverse
IEC
IEC-A
IEC-B
IEC-C
IEC-D
Moderately inverse
Very Inverse
Extremely Inverse
Definite Time
Ct Ratio = 1200:5 (Entered as “1200”)
Actual secondary current at pickup=7.5=(1800/1200) x 5
2-1.3 TIME SETTING
A Digitrip 3000 Protective Relay time setting is a pre-
selected time delay initiated when a pickup point on the
long or short curve is exceeded. If the current value drops
below the pickup value, the timing function resets.
Memory is NOT provided. If the current value does not
drop below pickup, the amount of delay before tripping
occurs is a function of the current magnitude and the time
setting. The delay can be determined from the appropriate
time-current curves.
2-1.4 PROTECTION CURVE SETTINGS
Curve Selection:
Extensive flexibility on inverse time
overcurrent (phase and ground) curve shaping is possible
with eleven available curve types. The selection and
associated result is determined by the type of curve shape
that best fits the coordination requirements (Figure 1-4,
Table 2.1). Different curve shape settings can be applied
to phase and ground to maximize coordination flexibility.
The curves are discussed in more detail in Paragraph 3-
3.1.
Note: The DT3000 displays pickup settings in the
“Settings” window to three significant digits only. If
there is a 4th digit in the setting, it will not be
displayed in the “Settings” window.
Phase Inverse Time Overcurrent Pickup:
The available pickup settings for the standard DT3000, shown below, range from
0.20 to 2.2 times (I
n
).
Phase Element Inverse Time Overcurrent Pickup –
Available Settings
Tolerance
Curve #
0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75,
0.80, 0.85, 0.90, 0.95, 1.00, 1.10, 1.20, 1.30, 1.40, 1.50, 1.60, 1.70,
1.80, 1.90,2.00,2.10, 2.20
±5%
The available pickup settings for the Chicago version (DT3100 and DT3101) are shown below, they range from 0.20 to 1.00
times (I
n
).
Phase Element Inverse Time Overcurrent Pickup –
Available Settings
Tolerance
Curve #
0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75,
0.80, 0.85, 0.90, 0.95, 1.00
±5%
Phase Inverse Time Overcurrent Time Multiplier:
The available time settings, shown below, depend on the curve shape
selected. For the thermal curves, the settings represent relay operating times at a current value equal to 3 times (I
n
). For ANSI
and IEC curves, the settings represent the relay’s time multiplier for the current value equal to I/I
pu
.
Phase Element Inverse Time Overcurrent Time Multiplier
Available Settings
Tolerance
Curve #
Curve = IT, I
2
T, I
4
T:
0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75,
0.80, 0.85, 0.90, 0.95, 1.00, 1.25, 1.50, 1.75, 2.00, 2.25, 2.50, 2.75,
3.00, 3.50, 4.00, 4.50, 5.00, 5.50, 6.00, 6.50, 7.00, 7.50, 8.00, 8.50,
9.00, 10.0, 12.5, 15.0, 17.5, 20.0, 22.5, 25.0, 27.5, 30.0, 35.0, 40.0
Curve = FLAT:
0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75,
0.80, 0.85, 0.90, 0.95, 1.00, 1.25, 1.50, 1.75, 2.00
Curve = ANSI MOD, VERY, XTRM:
0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5,
1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0,
3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5,
4.6, 4.7, 4.8, 4.9, 5.0
+10%
See Notes 1 & 2
± 0.05 seconds
±10%
See Notes 1 & 2
IT SC-5392-92B
I
2
T SC-5391-92B
I
4
T SC-5390-92B
FLAT
SC 5393-92B
MOD SC-6685-96
VERY SC-6686-96
XTRM SC-6687-96
