E-Mon E20-6003200J-D-KIT - Manual (Page 43)

CLASS 2000 METER
43 62-0389-05
This special high voltage meter installation shows the correct wiring procedure for 3-
wire high voltage circuits. In this application, the 2 element meter connection is used
on the secondary circuits of the user supplied high voltage PTs and CTs.
The E-MON meter used in this application is the model containing “12025 HV”.
Installation of these meters requires the use of two (2) current sensors mounted on the
secondaries of the high voltage Current Transformers. See the drawing above for
proper wiring. For correct operation, the meter must be installed correctly.
This special high voltage meter installation utilizes high voltage PTs (Potential
Transformers) and CTs (Current Transformers) supplied by others. The E-MON meter
is installed using the secondary outputs of these devices.
High voltage PTs reduce the primary voltage (4160v, 13200v, etc.) to a Secondary
output of 120v. This secondary is connected to the E-MON meter voltage inputs as
shown in the wiring diagram. High voltage CTs reduce the primary current (amps) to a
directly proportional 0~5 amp output. As an example, a 0~400 amp primary becomes a
0~5 amp proportional signal from the secondary output. This allows much smaller
wiring to be utilized in the meter hookup. The high voltage CT secondary is installed as
a continuous “loop”, with a single lead connected to both secondary terminals.
E-MON meters accept a 0~2 volt signal from their Current Sensors. To convert the 0~5
amp signal, the Current Sensors are installed on the CT secondary lead. A set of 25
amp sensors is used in this application. These sensors have the high voltage CT
secondary lead passed through them five (5) times by looping the wire as shown in the
drawing. This allows a direct conversion of the CTs primary current to a directly
proportional 0~2 volt signal, which is used by the meter.
Since there is a signal ratio introduced by the high voltage CTs and PTs, it will be
necessary to multiply the number on the meter’s display for a correct reading. The
meter multiplier is calculated by using the CT ratio and the PT Ratio. [PTr x CTr /
Number of Secondary Lead Passes Through Sensor]. The E-MON 25 amp HV kWh
meter with 5 wraps of the high voltage CT secondary will have its multiplier calculated
by the formula shown below.
EXAMPLE: CT = 400:5 = 80:1 (CTr = 80)
PT = 4200:120 = 35:1 (PTr = 35)
Wraps (Passes) = 5
METER MULTIPLIER = PTr x (CTr/Wraps)
35 x (80/5)
35 x (16) = 560