Introduction to Electrical Installation Testers
Electrical installation testers are multifunction instruments designed to perform various safety measurements in accordance with the IEC/EN 61557 standard. These devices are essential to ensure that electrical installations are safe and operate efficiently, identifying potential faults and verifying the correct functioning of electrical systems.
Measurements Performed by Electrical Installation Testers
Electrical installation testers perform several essential measurements to evaluate the safety and performance of electrical installations. Some of the most common measurements include:
Insulation Resistance Measurement
Insulation resistance measurement is crucial to ensure that electrical components and cables do not have leakage currents that could cause accidents or damage. It involves applying a continuous voltage between the active conductor and the ground or between active conductors. A high resistance value indicates good insulation. Generally, insulation measurement in an installation is performed between the phases and the neutral joined together on one side and the ground on the other side. If the insulation is insufficient, the measurement should be performed between each pair to locate the fault. That is why it is possible to index the recorded value with one of the following values: L-N, L-PE, N-PE, L1-PE, L2-PE, L3-PE, L1-N, L2-N, L3-N, L1-L2, L2-L3 or L1-L3. Some equipment has the TEST button option that allows the measurement to be performed more conveniently.
Conductor Continuity Measurement
This test verifies that protective conductors, such as grounding cables, are intact and do not have interruptions. It is performed by applying a low current and measuring the conductor's resistance. A low resistance value confirms the conductor's continuity. To comply with the IEC 61557 standard, measurements must be performed at 200 mA. Current reversal allows compensating for possible residual electromotive forces and, above all, verifying that continuity is bidirectional.
Loop Impedance Measurement
In a TN or TT type installation, loop impedance measurement allows calculating the short-circuit current and sizing the installation's protections (fuses or circuit breakers), especially in breaking capacity. In a TT type installation, loop impedance measurement allows easily determining the ground resistance value without driving in any stake and without cutting off the installation's power supply. The result obtained, ZS, is the installation's loop impedance between the L and PE conductors. It is slightly higher than the ground resistance. Knowing this value and the conventional contact limit voltage (UL), the assigned operating residual current of the differential can be chosen: IDN < UL / ZS. This measurement cannot be performed in an IT type installation due to the high impedance of the transformer ground connection and even its total isolation from the ground.
Leakage Current Measurement
This measurement detects leakage currents that could be hazardous. It is performed by connecting the tester in series with the circuit and measuring the current flowing to the ground. Leakage currents can indicate problems in insulation or connected devices.
3P Ground Resistance Measurement
This function is the only one that allows measuring ground resistance while the electrical installation to be tested is de-energized (e.g., a new installation). For this, two additional stakes are used, with the third stake being the ground to be tested (hence the name 3P). It can be used in an existing electrical installation but requires the current to be cut off (main differential). In all cases (new or existing installation), the test bridge must be opened during the measurement. A quick measurement can be performed to measure only RE, or a more detailed measurement can be performed by also measuring the stakes' resistances. There are several measurement methods. It is recommended to use the so-called “62%” method, but the measurement procedure is explained in more detail in the device's manual.
Voltage Ground Measurement Ra (1P) (on high-end equipment)
Equivalent to the 3P ground measurement, the voltage ground measurement allows substantial time savings: It does not require disconnecting the ground connection band and only requires an auxiliary stake (S). Additionally, this method ensures the safety of property and people in contact with the electrical installation as the ground is not disconnected. The 1P stake must be located outside the influence zone of the ground to be measured. There are two modes:
- Non-trip measurement with low current (6, 9, or 12 mA): For installations protected with 30 mA differential.
- High current measurement (or TRIP): Provides better measurement accuracy. It is also possible to calculate the fault voltage in case of phase-ground short circuit (Ufk) as defined in SEV 3755 standard.
Selective Voltage Ground Measurement Ra with Clamp (on high-end equipment)
In the case of grounding with multiple grounds connected in parallel (TN type installation), an optional clamp ammeter can be used as a complement to the voltage ground measurement. This selective voltage ground measurement function allows selecting one ground among others in parallel and knowing its exact value without disconnecting it from the rest of the ground network. To ensure high measurement accuracy, this Ra sel measurement is only available in high current mode (TRIP mode). Therefore, it is not possible to change the test current in this measurement.
RCD Tests (Residual Current Devices)
These tests verify the correct functioning of residual current circuit breakers, crucial for protection against electric shocks. They include:
- Trip Test: Applies a fault current to verify that the RCD trips correctly.
- Response Time: Measures the time the RCD takes to trip after detecting a fault current.
Phase Rotation Measurement
Some equipment includes phase rotation measurement, which allows controlling the phase sequence of a three-phase network. This is crucial to ensure the correct operation of motors and other three-phase equipment.
Examples of Multifunction Testers
PEAKTECH P2755:
The P2755 from Peaktech is a multifunction tester that performs all necessary measurements to comply with electrical safety standards. Its features include:
- Insulation resistance measurement
- Conductor continuity measurement
- Loop impedance measurement
- Leakage current measurement
- Ground resistance measurement
- RCD tests
- PC connectivity and data export software
For more information, visit the product page: P2755.
METREL MI3100 SE EurotestEASI:
The MI3100 SE EurotestEASI from METREL is an advanced tester offering a wide range of testing functions for electrical installations. Its features include:
- Insulation resistance measurement
- Continuity measurement
- Loop impedance measurement
- RCD tests
- Leakage current measurement
- Ground resistance measurement using the 3P method
- PC connectivity and data export software
For more information, visit the product page: MI3100 SE EurotestEASI.
CHAUVIN ARNOUX CA6116N:
The CA6116N from Chauvin Arnoux is a multifunction tester that allows performing various tests necessary to verify the safety of electrical installations. Its capabilities include:
- Insulation resistance measurement
- Conductor continuity measurement
- Loop impedance measurement
- Ground resistance measurement
- Leakage current measurement
- Ra (1P) voltage ground measurement using an optional clamp ammeter
- Selective 1P ground measurement
- Power and harmonics measurement through an optional clamp ammeter
- PC connectivity and data export software
For more information, visit the product page: CA6116N.
CHAUVIN ARNOUX CA6117:
The CA6117 from Chauvin Arnoux is one of the most advanced testers, offering extensive functions for analyzing and testing electrical installations. Its features include:
- Insulation resistance measurement
- Continuity measurement
- Loop impedance measurement
- Leakage current measurement
- Ground resistance measurement
- Selective 1P ground measurement
- Ra (1P) voltage ground measurement using an optional clamp ammeter
- Power and harmonics measurement through an optional clamp ammeter
- Frequency measurement
- Advanced diagnostic functions
- PC connectivity and data export software
For more information, visit the product page: CA6117.
