GE Multilin 745, Instruction Manual

Page: 196 / 242

General 745
Transformer Management Relay
Commission
ing
http://www.GEindustrial.com/multilin
7–2
GE Multilin
Though tests are presented in this section to verify the correct operation of all
features contained in the 745, only those features which are placed into service
need be tested. Skip all sections which cover features not included or not enabled
when the relay is in service, except for the provision of the next paragraph.
Some features such as the Local/Remote Reset of targets, display messages and
indications are common to all the protection features and hence are tested only
once. Testing of these features has been included with the Harmonic Restraint
Percent Differential, which will almost always be enabled. If, for some reasons, this
element is not enabled when the relay is in service, you will need to test the Local/
Remote Reset when testing another protection element.
Safety Precautions
Ensure the following precautions are observed before testing the relay.
HIGH VOLTAGES ARE PRESENT ON THE REAR TERMINALS OF THE RELAY,
CAPABLE OF CAUSING DEATH OR SERIOUS INJURY. USE CAUTION AND
FOLLOW ALL SAFETY RULES WHEN HANDLING, TESTING, OR ADJUSTING
THE EQUIPMENT.
DO NOT OPEN THE SECONDARY CIRCUIT OF A LIVE CT, SINCE THE HIGH
VOLTAGE PRODUCED IS CAPABLE OF CAUSING DEATH OR SERIOUS
INJURY, OR DAMAGE TO THE CT INSULATION.
THE RELAY USES COMPONENTS WHICH ARE SENSITIVE TO ELECTROSTATIC
DISCHARGES. WHEN HANDLING THE UNIT, CARE SHOULD BE TAKEN TO
AVOID ELECTRICAL DISCHARGES TO THE TERMINALS AT THE REAR OF THE
RELAY.
ENSURE THAT THE CONTROL POWER APPLIED TO THE RELAY, AND THE AC
CURRENT AND VOLTAGE INPUTS, MATCH THE RATINGS SPECIFIED ON THE
RELAY NAMEPLATE. DO NOT APPLY CURRENT TO THE CT INPUTS IN EXCESS
OF THE SPECIFIED RATINGS.
ENSURE THAT THE LOGIC INPUT WET CONTACTS ARE CONNECTED TO
VOLTAGES BELOW THE MAXIMUM VOLTAGE SPECIFICATION OF 300 V DC.
Conventions
The following conventions are used for the remainder of this chapter:
•
All setpoints and actual values are mentioned with their path as a means of
specifying where to find the particular message. For instance, the setpoint
WINDING 1 PHASE CT PRIMARY
, which in the message structure is located under
setpoints Page S2, would be written as:
S2 SYSTEM SETUP
!"
WINDING 1
!"
WINDING 1 PHASE CT PRIMARY
• Normal phase rotation of a three-phase power system is ABC.
• The phase angle between a voltage signal and a current signal is positive when
the voltage leads the current.
• Phase A to neutral voltage is indicated by V
an
(arrowhead on the “a”).
• Phase A to B voltage is indicated by V
ab
(arrowhead on the “a”).
• The neutral current signal is the 3 I
o
signal derived from the three phase
currents for any given winding.
• The ground current is the current signal measured by means of a CT in the
power transformer connection to ground.
Test Equipment
It is possible to completely verify the 745 relay operation using the built-in test and
simulation features described earlier in this manual. However, some customers
prefer to perform simple signal-injection tests to verify the basic operation of each
element placed into service. The procedures described in this chapter have been
designed for this purpose. To use the built-in facilities, refer to the appropriate
sections in this manual.
CAUTION
CAUTION
CAUTION
CAUTION
CAUTION