Metrel MI 3102H BT vs MPI-530: Comparing Significant Differences, Applications & Accuracy

Hello, I would like to ask for a reliable opinion and description of significant differences in the above-mentioned measures. I'm going to buy one of them. I need a meter to measure installations that I make myself. Possibly for commissioned measurements in companies / industrial plants.
For now, I am in favor of buying a Metrel (2.5kV), but I saw Sonel in action when I ordered measurements and I saw that it is quite intuitive.
Based on dry instructions, I compared both meters. And now a question for surveyors, which is more useful and what to choose? Metrel has resistance measurement at 2.5 kV, Sonel 1kV; Metrel cannot measure the earth resistance 4P, Sonel has the option of 4P; (which method do you most often use for these measurements?) Sonel has a more accurate loop impedance measurement down to 0.001, is it important?

What do you need a test voltage of 2.5kV for?
Do you make installations with an operating voltage above 400V?
Do you need to perform insulation measurements of power cables laid on the ground?
If you do not perform such measurements, you do not need 2.5kV, and to perform measurements of internal installations, max. 500V.

In addition, the decision which meter to choose also depends on the access to the service and laboratory in which you will have to calibrate the instrument.
Call yourself how much individual laboratories take for calibrating a given instrument.
As for the MPI series meters, they are really good and convenient to use meters. Unfortunately, I do not know Metrel and I am not able to say anything about it, because I used many different meters, but all of them were Sonela. The most measurements in my life have been made with the MPI-525 - several thousand per month.
The MPI-530 is its more extensive successor.
It's also a good idea to add some cash and buy a PE5 protocol program if you do a lot of them.

What about measuring WLZ? Is it treated as a cable between the meter box on the plot border and the house? Then, probably the standard prescribes 2.5 kV?

Since it is arranged with a YKY or YAKY cable, it should be treated as a cable.
But for 2.5kV measurements you can buy an inductor or an electronic meter for a few hundred.
You can also buy MPI-525 instead of MPI-530, which also has a range of 2.5kV and in this case it will probably be a better choice, and even a thousand in your pocket will stay.

What about the 3P and 4P method when measuring ground? When 4P is required for single family homes or industrial plants.

4P provides higher measurement accuracy.
There is probably no such clear indication in the standards. At least I have not found anything like that in PN-HD 60364-6 where the measurement methods are described.

However, when making measurements, the measurement error should be included in the measurement results.
In the case of residential houses or factories, this accuracy may be important in TT networks, where higher requirements are imposed on earthing, i.e. lower earth resistance, and lower expected touch voltages are required.
It may happen that, due to the limit value of the measurement results, the protection may not be classified as effective when using a less accurate method. And by performing a more accurate method, the measurement results may meet the protection requirements.

Do you need to perform insulation measurements of power cables laid on the ground?
If you do not perform such measurements, you do not need 2.5kV, and to perform measurements of internal installations, max. 500V.
Old regulations. Now the power cables are measured with the voltage "not less than 1000V". A measurement of 1000V is also sufficient.

webronin wrote:

Old regulations. Now the power cables are measured with the voltage "not less than 1000V". A measurement of 1000V is also sufficient.

I honestly admit that I would like it to be so, but is there any legal basis that allows WLZ made with a YKY cable to be measured with 1kV? In my opinion, since ZK is a customer installation, WLZ is no longer a power line, the voltage on it is always 230 / 400V, so why measure it with 2.5kV if the PN-HD 60364- -6: 2008 standard says about the voltage Up = 1kV .

Power cables with a rated voltage of 1kV and above should be measured with 2.5kV. Quote "The measurement should be made at a temperature of 15-25 degrees Celsius, humidity 40-75% for about 60s." Władysław Orlik TESTS AND ELECTRICITY MEASUREMENTS FOR PRACTICES.

Sentences are divided as you can see. I wrote to PKN for info on this matter. Gentlemen, however, you need 2.5 kV. The text of the reply from PKN I do not know if I can include it here. Let the admin speak.

webronin wrote:

Sentences are divided as you can see. I wrote to PKN for info on this matter. Gentlemen, however, you need 2.5 kV. The text of the reply from PKN I do not know if I can include it here. Let the admin speak.

A similar discussion was made at ise regarding cable measurements.
The question is whether the WLZ cable belonging to the recipient (from the operating limit) is a power cable?

webronin wrote:

Sentences are divided as you can see. I wrote to PKN for info on this matter. Gentlemen, however, you need 2.5 kV. The text of the reply from PKN I do not know if I can include it here. Let the admin speak.

Could you please send this answer in PW, I am very interested in their position.

Dear Mr. Chairman of KT55: Responding to the issues raised by e-mail xxxxxxxxx, regarding the ambiguity of the provisions of the PN-HD 60364-6: 2016-07 standard, with regard to the test voltage values that should be used when measuring insulation resistance in internal power lines installations of buildings, the following explanations are given. The scope of the PN-HD 60364-6: 2016-07 standard covers provisions on the acceptance and periodic testing of low voltage electrical installations, starting from their connection to electricity receivers. In the internal supply lines (WLZ) of these installations, there may be earth cables in the section between the connection and the main switchboard, but they do not fall within the scope of the standard under consideration, which is confirmed by the data contained in Table 6.1 of this standard. They clearly show that the test voltage for measuring the insulation resistance in circuits (without earth cables) with a rated voltage of Un 500 V - the value of 1000 V. the circuit of the internal power supply line of the LV installation. there is a section of the earth cable, which - as mentioned - does not fall within the scope of the standard in question, then the test voltage for measuring the insulation resistance in such a circuit should have a value of 2500 V. a specific product of a specific manufacturer meets the requirements of a given standard. They can only clarify doubts as to the correct reading of the provisions of a standard, which is not a legal regulation, but a technical document for voluntary application. PKN opinions are not of the nature of any administrative acts. Other bodies, e.g. certification bodies, are appointed to test the compliance of products with standards and legal regulations.

Thank you,
I have to look for this standard, especially Table 6.1. however, I see a few inaccuracies here:

First of all, PB indicates 60364-6: 2008 as the standard and until this changes, I plan to perform measurements in accordance with this standard.

Another thing is:

Quote:

The scope of the PN-HD 60364-6: 2016-07 standard covers the provisions on acceptance and periodic testing of low voltage electrical installations, starting from their connectors to electricity consumers . In internal supply lines (WLZ) of these installations, there may be earth cables in the section between the connection and the main switchboard, but they do not fall within the scope of the standard in question , which is confirmed by the data contained in Table 6.1 of this standard.

They taught me that the connection is between the connector and the switchgear, so it is within the scope of the standard, but for that I have to find this unfortunate table 6.1.

If you agree on something, let me know here on the forum. I will be very grateful. And not only me. As for the standards, there are many inaccuracies.

Table 6.1 shows that when the nominal voltage of the circuit up to and including 500 V, including FELV, the DC test voltage is 500 V, and the permissible resistance is 1 M?, and it applies to the main switchboard and individual circuits.
In other words, the Riso measurement can be made with a voltage of 500 V, and it makes no sense to torture the cable with a value of 2500 V.
I personally measure U pom. 1000 V, because I see no contraindications.
One more thing - the mentioned table 6.1 can be found in point 6.4.3.3 under the title Electrical installation insulation resistance in PN-HD 60364-6: 2016-07.
And yet before that I wrote:

Quote:

The question is whether the WLZ cable belonging to the recipient (from the operating limit) is a power cable?

elpapiotr wrote:

Table 6.1 shows that when the nominal voltage of the circuit up to 500 V inclusive, including FELV, the DC test voltage is 500 V, and the permissible resistance is 1 M?, and it applies to the main switchboard and individual circuits.

It is interesting where they read that:

Quote:

In the internal supply lines (WLZ) of these installations, there may be earth cables in the section between the connection and the main switchboard, but they do not fall within the scope of the standard under consideration, which is confirmed by the data contained in Table 6.1 of this standard.

As for me, the use of N-SEP-E-004 for the WLZ line guided by the YKY cable is strongly stretched, if the nominal voltage of the circuit is up to 500V. Following this lead, the YKY 3x1.5 mm? cable to the lamp next to the gate, I would also have to test 2.5 kV, just because it is pulled by a ground cable.

DrKubus wrote:

Following this lead, the YKY 3x1.5 mm? cable to the lamp next to the gate, I would also have to test 2.5 kV, just because it is pulled by a ground cable.

You'd have to be crazy to do something like that.

So where does the belief that I should test 2.5 kV from the connector (with a meter) to the switchgear come from? Since according to of all definitions it is a LV electrical installation acc. to of the referenced standard. And probably only the producers of 2.5 kV meters want it to be tested this way.

Hence, the password "cable" is used every time, and that's it.

It reminds me of the dispute about the necessity to have E to make measurements, even though PB clearly indicates that you need to have D + measurements