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ECM-1220 Connection

Brultech Research Inc (BRI) is proud of the ECM-1220's versatility. This model has been designed with the ability to monitor almost any residential and light commercial load.

By November 07, the ECM-1220 will have the ability to monitor two phase loads fed from a three phase service and certain 3 phase loads.

Because of BRI's forethought, the hardware has already been implemented in those monitors manufactured before Nov/07. It is simply a matter of upgrading the ECM-1220's firmware, to obtain these new features.

How The ECM-1220 Derives True Power

A brief explanation of how the ECM-1220 compiles the power used by a load will make it much easier to understand how to connect it and interpret the readings.

In order to meter true power, the load's current and voltage must be sampled. This must be performed in real time because something called "power factor" comes into play.

The ECM-1220 does this by sampling the current via current transformer (CT), and the voltage from the wall transformer, which is proportional to the line voltage. See diagram below.

Figure 1

One of the ECM-1220 settings is "PT Setting". This setting tells the ECM-1220 what secondary voltage coincides with 120V on the primary side. This value is preset at the factory and should only require changing for certain connection types. These values could be read from a label on the wall transformer.

The same principle applies to the "CT Setting". The ECM-1220 needs to be set to a value representing the appropriate current ratio of the current transformer.

Based on the diagram above, the channel in which the CT is plugged into will provide the power for that load.

Referring to figure 2, the load is connected to the opposite phase. Assuming the same load as that in figure1, the ECM-1220 will display the same power.

 

Figure 2

This setup may produce a slight error if Line1(black) voltage differs from Line2 voltage (red). This error is usually negligible since service panels are generally fairly balanced.

The technique used by the ECM-1220 when monitoring 240V loads is a combination of both figure1 and fugure 2. This technique is shown in figure3.

Figure 3

As you can see, an additional current transformer is used so that each line may be monitored by each channel. The total power for this load is then the sum of each channel.

There has been some confusion with this type of setup because a 240V load is monitored and 120V is displayed. Essentially, the same 120V is used to calculate the power of each channel.

Monitoring a 240V load using this method has the advantage of viewing the power of each half of the load separately. This is beneficial in determining how balanced the load is. For some loads, this provides greater insight, such as a clothes dryer with a 240V heating element and a 120V motor. The heating and motor power may then be calculated separately.

Examples of figure 1 and figure 3 may be all you will ever require for most applications. The next section will describe some variations of the above and techniques  for simpler and more complex application.

 

Connecting the ECM-1220 to Various Load Types

Please Note:

All examples below are based on 60Hz frequency. The ECM-1220 currently is not compatible with 50Hz systems.

Any installation which requires work inside service panels, junction boxes or other areas with live conductors should only be performed by a qualified individual having knowledge of the dangers involved, using proper safety practices and obeying all local electrical codes.

The example in figure 3 shows how to connect to a 3-wire 120V/240V load (Line1,Line2 and Neutral). Some 240V loads only use two wires, line1, line2 and no neutral. One such example is an electric baseboard heater.

Figure 4

You may simply use the same technique based on that of figure 3 (redrawn in figure 4), or you may prefer to monitor with only one CT, since the same current flows through line1 and line2 as shown in figure 5.

Figure 5

The setup in figure 5 allows the load to be monitored with only one CT using only one channel, allowing a second similar load to be monitored with the second channel.

There is one important difference to note in this example:

In figure 4, both channels were used, deriving the power for both halves of the 240V load and the power was the sum of both halves.

In figure 5, only one channel is used to derive the total power, therefore the load is treated like the basic example of figure 1, only now the ECM-1220 needs to assume a voltage of 240V, the actual load voltage. 

This is simply done by changing the PT Range from "3" to "2". This double the voltage value. The ECM-1220 will now display 240V, although powered by a 120V receptacle. The displayed power will represent the actual load power.

This method should only be used for applications where the load does not make use of the neutral connection.

You may run into a situation where you need to monitor a 240V load without having access to 120V. Figure 6 shows how to connect for this situation.

Figure 6

Since the ECM-1220's wall transformer may NOT be connected directly to 240V, Brultech has 240V:120V step down transformer available to use for this application. Once again, the ECM-1220 needs to know that you are monitoring a load connected to 240V. Therefore you will need to double the PT range by setting it to "2".

There is one important difference this time around! The step-down transformer does not provide a perfect 2:1 reduction ratio. This is easily compensated by adjusting the CT type. This value is supplied with the transformer if purchasing this option.

Under Construction ..... more examples coming

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