Eaton Digitrip 3000 series - SECTION 7: TIME-CURRENT CURVES; 7-1 DIGITRIP 3000 INVERSE TIME OVERCURRENT CURVES

DT3000 Instruction Leaflet
I.B. 17555D Effective: Date 07/02 Page 37
For more information visit: www.cutler-hammer.eaton.com
Supersedes I.B. 17555C dated November 1999
Circuit Breaker Trips
Much Faster than
Expected on Inverse
Time Overcurrent
(continued)
• Zone Interlocking Used • Check for Absence of Blocking Signal from
“Down-Stream” Breaker
NOTE: During an Internal Test, there is No
Blocking Signal from a “DownStream” Breaker,
therefore, add jumper for test.
• Paragraph 4-
2
Circuit Breaker Trips
Much Slower than
Expected on Inverse
Time Overcurrent
• The Short Delay Time
Setting Determines the
Minimum Inverse Time
Overcurrent
• Check Coordination Curves for Short Delay
and Inverse Time Overcurrent Settings
• Section 7,
Paragraph 3-
3.1
• Improper Wiring from
Protective Relay
• Check Trip Relay Wiring
NOTE: Instantaneous and Override Trip
Functions Close the Contact Between TB2-
12 and TB2-13, while Inverse Time
Overcurrent and External Trip Functions
Close the Contact Between TB2-14 and
TB2-15
• Check that Trip Contact on Protective
Relay makes
• Figure 3-1
• Figure 3-1
Protective Relay
Indicates a Trip, but
Circuit Breaker
Doesn’t Open
• Unit in Test Mode with “No
Trip Test Selected”
• Select Trip Test while in the Test Mode
• Check Wiring from Protective Relay to
Circuit Breaker Trip Coil
• Check that Circuit Breaker has Source of
Tripping Power
• Paragraph 3-
3.3
• Wiring Plan
Drawing
• Wiring Plan
Drawing
• Breaker Contact to
Protective Relay not
Functioning
• Check wiring from Breaker Dry Contact to
TB1-9 and TB1 -10 of Protective Relay
Terminal Block
• Figure 3-1
and 5-3
Auto-Reset Function
not Operational
• DIP switch S9 not set
correctly
• Check DIP Switch S9 Setting
• Check that Contact is Operational
• Table 5.1
• Figure 5-3
• Dip Switch S9 not set
correctly
• Check DIP Switch Setting • Table 5.1
Manual Reset
Function not
Operational
• Damaged Reset
Pushbutton
• Replace Protective Relay • Paragraph 6-
3
Caution: When the Digitrip 3000 Protective Relay is Powered, it Supplies Voltage to the “b” Contacts
SECTION 7: TIME-CURRENT CURVES
7-1 DIGITRIP 3000 INVERSE TIME OVERCURRENT
CURVES
The following pages contain the specific time-current
curves applicable to the Digitrip 3000 Protective Relay.