Subscribing is a smart move!
You can subscribe to this forum after you log in or create your free account.
PM8240 - TNS without a 4th current transformer
Metering & Power Quality
Schneider Electric support forum about Power Meters (ION, PowerTag, PowerLogic) and Power Quality from design, implementation to troubleshooting and more.
Invite a Co-worker
Send a co-worker an invite to the portal.Just enter their email address and we'll connect them to register. After joining, they will belong to the same company.
Send Invite Cancel
Solved
Go to Solution
Link copied. Please paste this link to share this article on your social media post.
Hi,
The net is TNS. So we choose 4W-Wye in the setup of the PM8240.
But there isn't a current transformer placed on the Neutral.
Now we see for I5 (ground?) 40A and for I4 (Neutral) 0A. But I4 should be around 40A.
The Compact NSX, placed upstream of the PM8240, shows around 40A for the Neutral.
1. How to wire the I4 terminals when we do not have a current transformer?
Like shown on screenshot 1A or like shown on screenshot 1B? Or is this not so important?
2. Where to tell the PM8240 that a fourth current transformer is not present and that it should calculate the Neutral? (This is possible with a PM5560.)
Thanks!
BR,
Philippe
Accepted Solutions
Link copied. Please paste this link to share this article on your social media post.
If you have only 3CTs for a 3 phase system (with either 3 or 4 wires), you should use the "3CT" wiring diagram.
Ideally, one of the I4 terminals should be jumpered to the grounded CT common, but it should also work fine if I4 is not connected.
The "I5" measurement on the PM8240 is the calculated residual current of I1 + I2 + I3 + I4. So when I4 is not used (as shown above) and you have a 4wire system, this should be the neutral current.
If the I5 measurement is not your expected neutral current, you may have have a CT polarity, phase swap, or ground fault issue.
I recommend do NOT simply connect I4+ to I4- as it can become a loop antenna that may allow the meter to register when in close proximity to AC magnetic fields.
Link copied. Please paste this link to share this article on your social media post.
If you have only 3CTs for a 3 phase system (with either 3 or 4 wires), you should use the "3CT" wiring diagram.
Ideally, one of the I4 terminals should be jumpered to the grounded CT common, but it should also work fine if I4 is not connected.
The "I5" measurement on the PM8240 is the calculated residual current of I1 + I2 + I3 + I4. So when I4 is not used (as shown above) and you have a 4wire system, this should be the neutral current.
If the I5 measurement is not your expected neutral current, you may have have a CT polarity, phase swap, or ground fault issue.
I recommend do NOT simply connect I4+ to I4- as it can become a loop antenna that may allow the meter to register when in close proximity to AC magnetic fields.
Create your free account or log in to subscribe to the forum - and gain access to more than 10,000+ support articles along with insights from experts and peers.