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CHAPTER 2: INSTALLATION
2.2.2
Control Power
2.2.3
VT Inputs
2.2.4
CT Inputs
PQM POWER QUALITY METER – INSTRUCTION MANUAL
Courtesy of NationalSwitchgear.com
The control power supplied to the PQM must match the installed power
supply. If the applied voltage does not match, damage to the unit may occur.
Check the product identification to verify the control voltage matches the
CAUTION
intended application.
A universal AC/DC power supply is standard on the PQM. It covers the range 90 to 300 V DC
and 70 to 265 V AC at 50/60 Hz. It is not necessary to adjust the PQM if the control voltage
is within this range. A low voltage power supply is available as an option. It covers the
range 20 to 60 V DC and 24 to 48 V AC at 50/60 Hz. Verify from the product identification
label that the control voltage matches the intended application. Connect the control
voltage input to a stable source for reliable operation. A 2.5 A HRC fuse is accessible from
the back of the PQM via the fuse access door. Consult the factory for replacement fuses, if
required. Using #12 gauge wire or ground braid, connect Terminals 5 and 6 to a solid
system ground, typically a copper bus in the switchgear. The PQM incorporates extensive
filtering and transient protection to ensure reliable operation under harsh industrial
operating environments. Transient energy must be conducted back to the source through
Filter Ground Terminal 5. The Filter Ground Terminal (5) is separated from the Safety
Ground Terminal (6) to allow dielectric testing of switchgear with the PQM wired up. Filter
Ground Terminal connections must be removed during dielectric testing.
When properly installed, the PQM meets the interference immunity requirements of
IEC 801 and ANSI C37.90.1.
The PQM accepts input voltages from 0 to 600 V AC between the voltage inputs (V
and voltage common (V
). These inputs can be directly connected or supplied through
n
external VTs. If voltages greater than 600 V AC are to be measured, external VTs are
required. When measuring line-to-line quantities using inputs V
the voltage common input V
n
the voltage inputs.
All connections to the PQM voltage inputs should be connected using HRC
fuses rated at 2 Amps to ensure adequate interrupting capacity.
CAUTION
Current transformer secondaries of 1 A or 5 A can be used with the PQM for phase and
neutral sensing. Each current input has 3 terminals: 5 A input, 1 A input, and common.
Select either the 1 A or 5 A terminal and common to match the phase CT secondary.
Correct polarity as indicated in the wiring diagrams is essential for correct measurement of
all power quantities.
The CTs selected should be capable of supplying the required current to the total
secondary load, including the PQM burden of 0.1 VA at rated secondary current and the
connection wiring burden.
All PQM internal calculations are based on information measured at the CT and
VT inputs. The accuracy specified in this manual assumes no error contribution
from the external CTs and VTs. To ensure the greatest accuracy, Instrument
NOTE
class CTs and VTs are recommended.
is grounded. This input is used as a reference for measuring
ELECTRICAL
, V
, V
)
1
2
3
, V
, and V
, ensure that
1
2
3
2–15
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