MD-3000
Instruction Leaflet
IB02602001E
Effective: Date 03/06
For more information visit:
www.EatonElectrical.com
Initial Release
1-1.1 WARRANTY AND LIABILITY INFORMATION
NO WARRANTIES, EXPRESSED OR IMPLIED,
INCLUDING WARRANTIES OF FITNESS FOR A
PARTICULAR PURPOSE OF MERCHANTABILITY, OR
WARRANTIES ARISING FROM COURSE OF DEALING
OR USAGE OF TRADE, ARE MADE REGARDING THE
INFORMATION, RECOMMENDATIONS AND
DESCRIPTIONS CONTAINED HEREIN.
In no event will Eaton Cutler-Hammer be responsible to
the purchaser or user in contract, in tort (including
negligence), strict liability or otherwise for any special,
indirect, incidental or consequential damage or loss
whatsoever. Including but not limited to damage or loss of
use of equipment, plant or power system, cost of capital,
loss of power, additional expenses in the use of existing
power facilities or claims against the purchaser or user by
its customers resulting from the use of the information and
descriptions contained herein.
1-1.2 SAFETY PRECAUTIONS
All safety codes safety standards and/or regulations must
be strictly observed in the installation, operation and
maintenance of this device.
THE WARNINGS AND CAUTIONS INCLUDED AS
PART OF THE PROCEDURAL STEPS IN THIS
DOCUMENT ARE FOR PERSONNEL SAFETY AND
PROTECTION OF EQUIPMENT FROM DAMAGE.
THIS IS AN EXAMPLE OF A TYPICAL WARNING
LABEL. THIS WILL HELP TO ENSURE THAT
PERSONNEL ARE ALERTED TO CAUTIONS THAT
APPEAR THROUGHOUT THE DOCUMENT.
COMPLETELY READ AND UNDERSTAND THE
MATERIAL PRESENTED IN THIS DOCUMENT
BEFORE ATTEMPTING INSTALLATION,
OPERATION OR APPLICATION OF THE
EQUIPMENT. ONLY QUALIFIED PERSONS
SHOULD BE PERMITTED TO PERFORM ANY
WORK ASSOCIATED WITH THE EQUIPMENT. ANY
WIRING INSTRUCTIONS PRESENTED IN THIS
DOCUMENT MUST BE FOLLOWED PRECISELY.
FAILURE TO DO SO COULD CAUSE PERMANENT
EQUIPMENT DAMAGE, BODILY INJURY OR
DEATH.
1-2 GENERAL INFORMATION
The MD-3000 Protective Relay is a panel-mounted
microprocessor based self-balancing differential current
relay, designed for both ANSI and IEC applications
(Figures 1-1 and 1-2). It is a self-contained device that
operates from either ac or dc control power and provides
true rms sensing of each phase differential current. Only
one relay is required per three-phase circuit. An integral
part of each device is the differential current
monitoring
and the ability to select protective functions.
THE LOSS OF CONTROL VOLTAGE WILL CAUSE
THE MD-3000 TO BE INOPERABLE. IF AC
CONTROL VOLTAGE IS USED AN APPROPRIATE
RELIABLE POWER SOURCE/SCHEME SHOULD
BE SELECTED (POSSIBLY AN UPS SYSTEM) TO
SUPPLY POWER TO THE RELAY.
The MD-3000 Motor/Generator Protective Relay provides
differential current protection for motors and generators.
MD-3000 Protective Relays are compatible for use with all
circuit breakers utilizing a shunt trip coil.
The MD-3000 is intended to replace electromechanical
differential protection relays.
1-3 FUNCTIONS/FEATURES/OPTIONS
The primary function of the MD-3000 Protective Relay is
differential overcurrent protection. This is achieved by
analyzing the secondary current signals received from the
switchgear current transformers. This secondary current
represents the current differential between the input and
output of a motor or generator. When the user
programmed current levels are exceeded for a period of
time greater than the user programmed time delay setting,
the closing of trip contact(s) is used to initiate breaker
tripping.
The MD-3000 Protective Relay operates from the
secondary output of standard switchgear current
transformers rated at 5 amperes. It is configured to fit
specific distribution system requirements. The phase CT
ratios can be independently programmed over a range of
5:5 to 5000:5. Refer to Table 2.1 for the available CT ratio
settings.
The relay automatically exits the program mode if there is
no programming activity for 2-1/2 minutes. Programming
and test mode security are provided by a sealed, hinged
access cover on the front of the relay. Displays indicate
the value currently being considered, while multi-colored
LED’s indicate operational conditions and specific
functions.
In addition to performing a continuous self-testing of
internal circuitry, all MD-3000 Protective Relays include
field testing capabilities that are accessible from the front
panel. To check that all tripping features are functioning
properly a test current simulates a differential overcurrent
condition. Refer to Paragraph 2-1.5 for additional
information.
MD-3000 Motor/Generator Differential Relay operating
parameters and troubleshooting information are displayed
WARNING
