PM
-
3133 User
’s Manual v1.09
Last Revised: Jun. 2021 Page: 66
Copyright © ICP DAS Co., Ltd. All Rights Reserved.
E-mail: service@icpdas.com
Q10. Can I use CT's that I currently own with PM-3133 Power Meter?
You can use CT's that you currently own with PM-3133P (without CTs) Power Meter.
The CT inputs of the PM-3133P can handle a maximum of 333mV of AC current.
PM-3133P's current ratio is always full scale to 5A. CT ratio can be set internally to work
with up to 1200 amp CTs.
Adding current transformer (333mV Output CTs) has the effect of reducing the measured
current by the CT ratio (let's say 40:1 for 200A CT as example). So a current of 200A
becomes 5A. Since the meter sees 5A, many of the measurements it reports will be low
by a factor of 40 unless they are scaled up by 40.
Current
transformer
CT Ratio
(PM-3133P)
Current
transformer
CT Ratio
(PM-3133P)
50A CT
10:1
400A CT
80:1
60A CT
12:1
800A CT
160:1
100A CT
20:1
1000A CT
200:1
200A CT
40:1
1200A CT
240:1
Note:
A. Please use low phase angle error CTs: essential for accurate power and energy
measurements. (Example: phase error <2°)
B. Primary CT accuracy will influence the measurement.
C. PM-3133P only for external 333mV Output CTs.
Safe: burden resistor built-in, 333 mVac voltage output at rated full scale current, no
shorting blocks needed.
D. This meter requires external CT(s) to operate:
1P2W-1CT requires 1 CT per meter.
3P3W-2CT/1P3W-2CT requires 2 CTs per meter.
3P4W-3CT/3P3W-3CT requires 3 CTs per meter.
Q11. What is the difference between line to line voltages to line to ground voltage?
On a three phase wye connected system line to line voltages will be the voltages between
the terminals A - B, B - C, A - C. On a three phase wye connected system line to ground
voltages will be the voltages between the terminals A - N, B - N, C - N. To calculate the line
to ground voltages divide the line voltage by the square root of three which equals 1.73. An
example, on a 380 volt wye system, line to line voltage is 380 volts and line to ground
