How to avoid common errors when installing measuring equipment

Installing a device correctly is not a simple task, since there are many aspects to consider to ensure it works correctly. The slightest mistake can affect the values measured by a device. What aspects do you need to consider? What are the potential problems? It is important to have all the data in order to solve any problems that have occurred, and prevent those that haven't.

In this article, we explain what the most common problems are when installing devices to measure electrical parameters, what their consequences are and how to solve them.

Illustration 1. Voltage-current phasor diagram

Problem 1: Phase synchronization

As illustration 1 shows, the voltages and currents of each corresponding phase need to have the same lead/lag angle at all times to ensure the correct operation of the installation. In order for the readings to be correct, the devices responsible for measuring electrical parameters must be installed in such a way that the voltages and currents correspond to the relevant angles.

Illustration 2. Incorrectly wired measuring device

Illustration 2 shows how a device is being used to measure the voltage and current in the 3 phases of a three-phase installation, but two of the wires used to measure the voltage are using the incorrect line as a reference. As a result, line 3 will show the right numbers, since it is measuring the voltage and current from the same phase. By contrast, the measurements for phases 1 and 2 will be incorrect, since the current and voltage are not for the same phase and will be out of sync.

This incorrect connection yields wrong readings for some extremely important parameters, such as power, cos phi, power factor or energies.

Suppose you have to measure an installation in order to install a capacitor bank. An incorrect power factor reading could lead you to think you need a bigger or smaller bank than you actually need.

Another example: you have to take a reading before installing energy management software. If you measure the wrong power, the devices that process the data would be set up wrong. And this could even lead to economic fines.

Illustration 3. Incorrectly installed current sensors

Problem 2 Error in the current sensors

Installing the current sensors incorrectly can yield readings that differ greatly from reality. As illustration 3 shows, line 3 has a current sensor (a transformer, clamps, etc.) that is installed in the opposite direction to the current flow.

We start from the assumption that the consumption in an installation is based on the sum of the line currents. If one of them has the current sensor backwards, this means that a generated current is measured as consumed, or vice versa. The result would be a current reading that is divorced from reality.

We'll give you another example: we are going to install current sensors, as shown in illustration 3, and a current of 5A is flowing in each line. As a general rule, the installation would be consuming 15A, since the sum of the currents in the 3 lines is 5 + 5 + 5 = 15A.

In this specific case, since the current sensor for line 3 is installed backwards, we will get a current of 5 + 5 - 5 = 5A. This small error can give a measurement that is two-thirds smaller than it really is.

If we rely on the accuracy of this figure, we would manage the power in a way that could result in financial penalties for excess loads. If, however, we realize the measurement error, we would have to go to the installation, reverse the direction of the current sensors and take the reading again.

Illustration 4. Circuit FLEX clamps

Problem 3: Configuration of the current clamps

The current clamps can be set up to work in several current ranges. They can measure anything above a minimum value, but there are set ranges to ensure they measure with the accuracy specified by the manufacturer. Measuring a current with clamps that are outside the specified configuration range can considerably reduce the measurement accuracy. It is therefore essential that the current flowing through the wires being measured be within the current range specified by the user.

This table shows the minimum current and the current range of Circutor's FLEX clamps

Below, we provide a couple of examples based on these values:

• Assume that 20 amps is flowing through the wires. If we used the first clamp configuration, the device would be above the minimum current setting. It measures and is also within the current range. This guarantees that the measurement is within the accuracy provided in the device's technical specifications.
• Assume that in this same installation, the clamps are set up using the second option. This value is above the minimum current. The current can be measured, but it is outside the range, causing a loss of accuracy.
• Finally, if the third option is used in this installation, the clamps would not give any readings. We would need a minimum of 500 amps to be flowing in order to take a reading using this configuration.

MYeBOX, Portable power analyzer with recording of quality events and transients

In conclusion, it is clear that an incorrect connection leads to wrong readings for electrical parameters. But there are many more indirect consequences: An incorrect connection means that the user has to travel to where the device is located in order to change the connection, with the corresponding transport, personnel and time costs. If the company is relatively close, this expense may not be very significant. But if, for example, it is located in a foreign country, the costs start to add up.

Fortunately, CIRCUTOR's devices let you set up the correspondence between the phases, specify the current direction measurement and change how the clamps are installed, all of it remotely.. By using a program installed on the user's own PC called Power Studio, you can connect to devices anywhere in the world and set up multiple configurations. This way, you can solve each and every one of the measurement problems detailed above, which are the most common in the industry. As a result, you can save unnecessary expenses and gain efficiency.

In short, although measurement errors have many negative consequences, CIRCUTOR makes it easy for you to avoid them, and, if they are unavoidable, to minimize them.