Safety Precautions; Conventions - GE TRANSFORMER MANAGEMENT RELAY 745 Instruction Manual

8.1 GENERAL
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, TEST-
ING, OR ADJUSTING THE EQUIPMENT.
CAUTION
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.
CAUTION
THE RELAY USES COMPONENTS WHICH ARE SENSITIVE TO ELECTROSTATIC DISCHARGES. WHEN
HANDLING THE UNIT, CARE SHOULD BE TAKEN TO AVOID ELECTRICAL DISCHARGES TO THE TERMI-
NALS AT THE REAR OF THE RELAY.
CAUTION
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
CAUTION THE CT INPUTS IN EXCESS OF THE SPECIFIED RATINGS.
ENSURE THAT THE LOGIC INPUT WET CONTACTS ARE CONNECTED TO VOLTAGES BELOW THE MAXI-
MUM VOLTAGE SPECIFICATION OF 300 V DC.
CAUTION
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 mes-
sage. For instance, the setpoint
points Page S2, would be written as:
S2 SYSTEM SETUP
• 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
• Phase A to B voltage is indicated by V
• The neutral current signal is the 3I
• The ground current is the current signal measured by means of a CT in the power transformer connection to ground.
8
8-2
Courtesy of NationalSwitchgear.com
WINDING 1 PHASE CT PRIMARY
WINDING 1 WINDING 1 PHASE CT PRIMARY
(arrowhead on the "a").
an
(arrowhead on the "a").
ab
signal derived from the three phase currents for any given winding.
o
745 Transformer Management Relay

8.1.3 SAFETY PRECAUTIONS

, which in the message structure is located under set-
8 COMMISSIONING

8.1.4 CONVENTIONS

GE Multilin