1
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Introduction
Focal points
- Installation of the current transformer, P1 side toward the power supply.
- Attach the transformer with colson straps.
- Connect white wire/S1 of the transformer to the positive terminal of the energy meter.
- Connect black wire/S2 from the transformer to the negative terminal of the energy meter.
- Adjust for incorrect connection using energy meter settings.
- Check connection of the RJ12 cable on a three-phase transformer thoroughly, must click 2 times. See also the section RJ12 cable connection in Chapter 3 of this manual.
- Tighten the cables running through the transformer with cable spacers.
Types
Calculus offers the following Eastron meters:
- SDM120MOD Energymeter 45A - 1F - ModBus - MID
- SDM230MOD Energymeter 100A - 1F - ModBus - MID
- SDM630MCT - Modbus - MID - V2 - 3F/100A
- SDM630MCT - ML - 1L - MID - 3F - ModBus - 1xRJ12CT
- SDM630MCT - ML - 2L - MID - 3F - ModBus - 2xRJ12CT
- SDM630MCT - ML - 4L - MID - 3F - ModBus - 4xRJ12CT
- SDM630MCT - MODBUS - MID - 3F - CT
- SDM630MCT-RC - ModBus - Rogowski Coil - MID
- Eastron SDM72D-M-2-MID Energymeter - 3F - ModBus - MID
The type of energy meter is indicated above the energy meter display.
Information regarding the specifications such as, for example: 3x230/400V can be found below the display (see image above).
See also the manuals and data sheets attached.
2
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Current transformers
Current transformers reduce high-voltage currents to a much lower value and provide a safe and convenient way to control the actual electric current flowing in an AC transmission. CTs work by converting primary current into secondary current through a magnetic medium. They allow energy meters to measure current on circuits that, if they measured the current directly, would overload the meters. In general, most meters can measure up to a maximum of 100 A of current before needing CTs to read higher values.
CTs are available for both single-phase or three-phase installations.
Types of current transformers
Solid core:
Fixed-core CTs form a fully enclosed core. To install a CT with a stable core, the conductor must be disconnected to get it through the CT core.
Split core:
Split core CTs have a “split” in the core that allows the CTs to be opened and placed around the conductor without the need to disconnect the conductor or interrupt the wiring. Just disconnect the coil, wrap it around the load you are measuring and reattach it!
Split cores are only used with the 630 MCT – MOD – MID energy meter.
Split core’s go from the T24 / T36. This is the diameter of the opening, through which the power cable goes when the split core is attached. So 24 mm or 36 mm.
Information regarding the type and specifications can be found on the CT itself.
Flow direction in a current transformer
The primary current enters the current transformer on the side marked P1. The load should be installed on the side marked P2.
If the primary current comes in on the P2 (in case of a faulty connection) then the current may be displayed as produced current instead of consumed current.
However, you can adjust the settings on the power meter so that, for example, the P2 is observed as the input of the primary current.To do this, you need to go to the “Set System Continued” menu in the power meter settings.
|
Use
|
| This screen is displayed, you can change “Forward” to “Reverse” for each individual CT connection. |
|
Hold down
|
and
to select the menu option. Press
and hold to display the submenu.
to confirm your adjustment. You can then proceed to IB or IC with
3
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Installing a current transformer
Single-phase
Pull the power cable through the current transformer if the transformer is solid.
If it is v/h split core type then you can snap it onto the power cable without disconnecting it.
Use colson straps to secure the transformer securely.
To wire the amp meter correctly, connect the positive coil (white wire / S1) of the CT to the positive terminal of the amp meter and the negative terminal of the CT to the negative terminals (black wire / S2) of the amp meter.
Make sure the cables are connected correctly!
If connected incorrectly, there is the possibility that the current will be measured incorrectly. For example: connect black wire to the positive terminal of the ammeter.
Also be mindfull when connecting the N (neutral) and GND (ground / grounding).
Three-phase
Example of a wiring diagram of a gateway + power meter:
The power meter passes power to the mean well HDR-15-24 power supply via the auxiliary supply ports 5 and 6, port 7 is connected to the L and port 8 to the N.
The gateway is then connected to the power supply.
An example of a wiring diagram of the energy meter SDM630MCT-ML:
RJ12 cable connection
Make sure when connecting the RJ12 cable that it is securely attached!
When you push the cable in, you will hear an initial click. The connection then looks like this
Insert the cable further and you will hear a second click.
Be mindfull that the cables are connected properly!
If connected incorrectly, there is the possibility that the current will be measured incorrectly.
For example, connect the S1 of phase L1 to the negative terminal of the ammeter.
The cables running through the CT can be tightened using cable spacers. These are shown in the image below.
Information on setting the different types of energy meters can be found in the section power & energy monitoring.
Questions or comments
If any information in this manual is missing, incomplete or incorrect, please do not hesitate to contact us through this article. We will happily explain further