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GE Multilin 489 Generator Management Relay 2-9
2 INSTALLATION 2.2 ELECTRICAL
2
2.2.3 CONTROL POWER
Control power supplied to the 489 must match the installed switching power supply. If the applied voltage
does not match, damage to the unit may occur.
The order code from the terminal label on the side of the drawout unit specifies the nominal control voltage as one of the
following:
• LO: 20 to 60 V DC; 20 to 48 V AC
• HI: 90 to 300 V DC; 70 to 265 V AC
Ensure applied control voltage and rated voltage on drawout case terminal label match. For example, the HI power supply
will work with any DC voltage from 90 to 300 V, or AC voltage from 70 to 265 V. The internal fuse may blow if the applied
voltage exceeds this range.
Figure 2–11: CONTROL POWER CONNECTION
Extensive filtering and transient protection are built into the 489 to ensure proper operation in harsh industrial environ-
ments. Transient energy must be conducted back to the source through the filter ground terminal. A separate safety ground
terminal is provided for hi-pot testing.
All grounds MUST be hooked up for normal operation regardless of control power supply type.
2.2.4 CURRENT INPUTS
a) PHASE CURRENT
The 489 has six phase current transformer inputs (three output side and three neutral end), each with an isolating trans-
former. There are no internal ground connections on the CT inputs. Each phase CT circuit is shorted by automatic mecha-
nisms on the 489 case if the unit is withdrawn. The phase CTs should be chosen such that the FLA is no less than 50% of
the rated phase CT primary. Ideally, the phase CT primary should be chosen such that the FLA is 100% of the phase CT
primary or slightly less. This will ensure maximum accuracy for the current measurements. The maximum phase CT pri-
mary current is 50000 A.
The 489 will measure correctly up to 20 times the phase current nominal rating. Since the conversion range is large, 1 A or
5 A CT secondaries must be specified at the time of order such that the appropriate interposing CT may be installed in the
unit. CTs chosen must be capable of driving the 489 phase CT burden (see SPECIFICATIONS for ratings).
Verify that the 489 nominal phase current of 1 A or 5 A matches the secondary rating and connections of
the connected CTs. Unmatched CTs may result in equipment damage or inadequate protection. Polarity of
the phase CTs is critical for phase differential, negative sequence, power measurement, and residual
ground current detection (if used).
CAUTION
NOTE
CAUTION