Residual Current Monitoring

Posted on: January 21st, 2022 by Doug Lovell

Any electrical leak can be lethal and dangerous for your staff and production site. By using Danisense Residual Current Monitor (RCM) you can protect both staff and equipment, avoid expensive breakdowns – and, even mandatory inspections. Furthermore, you can now get the Smart RCM with PC software for data analysis providing additional monitoring features.

With the multiplication of power electronic devices used in industrial and commercial installations creating DC and high-frequency residual current, the traditional type A residual current device could achieve its limits and not work properly.

Thanks to its zero-flux technology expertise, Danisense developed a range of highly flexible Residual Current Monitor of Type B/B+ for measuring DC and AC residual currents up to 100kHz, with analogue 4-20mA and relay output.

Danisense Residual Current Monitoring – RCM is characterised by

·       Large aperture (70 mm).

·       Setting of

– Rated RC limit (30, 100, 300, 500 and 1,000 mA).

– Frequency range (100, 2,000, 20,000 and 100,000 Hz).

– Integration time (Short, Medium, Long).

  • Rated residual operating current in combination with full compliance with the new norm IEC62020-1.
  • Locally or remotely operated.

New: Smart Residual Current Monitoring – RCM with PC software for data analysis

The latest version of Danisense RCM is controlled by PC (via USB) for data analysis and provide you with the following additional monitoring features:

  • FFT (Fast Fourier transform): The frequency spectrum of the measurement.
  • TRMS calculation for the individual low-frequency pass windows selected by you. TRMS is calculated very accurately via the FFT. Typically used for setting the rated RC limit and frequency range.
  • Remote setting of

– Rated RC limit

– Frequency range

– Integration time

  • Time logs off TRMS and relays data.
  • Relay trigger info – for instance, info about last time the residual current has been overdue.
  • General info for the selected settings.

In Germany, it is mandatory to test and validate production facilities at least every 4 years. Unless the company has Residual Current Monitoring (RCM) installed.


Daninsense Software - Telonic 2


The Info window gives a good overview with several individual options. Always shown are remote settings of the rated RC limit, frequency range, and integration time.

Another feature is ”Device info” showing supply voltage, temperature, and firmware version. Furthermore, serial number and individual naming of device locations.

Also, testing of the relay is a direct option.

Danisense software FFT window - Telonic UK

The FFT window shows the frequency spectrum of the measurement and corresponds to TRMS calculations of the frequency ranges. Top: Time domain of the measurement.

Mid: Shows Ranges and TRMS.

Bottom: The frequency domain spectrum

Other features include a copy to the clipboard and log / linear scale.

Danisense software data logging window - Telonic UK

Data logging shows time logged off TRMS data and relay status. Among the features, other features are “copy to clipboard”.

How does residual current monitoring work?

A Residual Current protective Device (RCD) has been a standard component in electrical sub-distribution for many decades. There is also an RCD at home, which has a rated residual current of 30 mA. Tripping between 50 and 100 % of the rated residual current is specified in the international standard. If the 30 mA RCD trips, a residual current must be bigger than 15 mA. The threshold of 30 mA is intended to ensure personal protection, which is required wherever freely accessible sockets are available. Currents from 50 mA onwards are life-threatening.

In the manufacturing industry environment, we usually find larger machines that are used for production. Even if these machines do not have any freely accessible sockets, RCDs are often used for different safety issues. They are designed to provide safety for three types of protection which are described in the following table.

Danisense Table -Telonic UK


A system failure can lead to electrical fires. Major damage to the system could also be prevented if a minor defect could be detected at an early stage. A major disadvantage when protecting the systems with an RCD is then an unforeseeable sudden shutdown of the system. In some branches of industry, an uncontrolled and unexpected system shutdown can quickly result in costs in the five to six-figure range.

This is remedied by Residual Current Monitors (RCM) with which the residual current can be measured. An increase in the residual current can be detected and reported at an early stage. A controlled shutdown of the production plant guarantees better-coordinated repair measures. The availability of the system can be increased. The probability of a production downtime decreases. An RCM is part of predictive maintenance.

Danisense RCD vs RCM Telonic UK


The figure above clearly shows that, in contrast to the RCD, an RCM cannot independently interrupt the supply line. The differential current is only measured and outputted via a suitable interface. In addition, RCMs have one or more relay outputs, which in turn can be used to control circuit breakers.



Which standard must a residual current monitoring device comply with?
Residual current monitoring devices can offer significant added value for any company with electrical installations. As mentioned in the IEC 60364-6:2016 there has to be a periodic verification of electrical installations or productions plants. This periodic verification is described as follows: Periodic verification shall be carried out without dismantling, or with partial dismantling, as required, supplemented by appropriate tests and measurements from Clause 6.4, to provide for:

the safety of persons and livestock against the effects of electric shock and burns,
protection against damage to property by fire and heat arising from an electrical installation defect,
confirmation of correct rating and setting of protective devices required by IEC 60364-4-41,
confirmation of correct rating and setting of monitoring devices,
confirmation that the installation is not damaged or deteriorated to impair safety,
the identification of installation defects and non-compliance with the requirements of the relevant parts of the IEC 60364 series, that may give rise to danger,
confirmation of correct rating and setting of protective devices, and
confirmation of correct rating and setting of monitoring devices.

Where a circuit is permanently monitored by a residual current monitoring device (RCM) in accordance with IEC 62020 or an IMD in accordance with IEC 61557-8 it is not necessary to measure the insulation resistance if the function of the IMD or RCM is correct.

The functioning of the RCM or IMD shall be verified.
As we can see it is expressly stated that measurement of the insulation resistance in the periodic verification can be replaced by a residual current monitoring device in accordance with high-frequency now read the IEC 62020 which monitors permanently the residual current in conjunction with continuous maintenance by qualified electricians.

Another area of application of the RCM is the protection of production plants against fire. Around 30 percent of all registered fires can be traced back to faults or defects in electrical systems. The protection via an RCD with 300 mA can often lead to false tripping due to the very high system-related residual currents of the system. This is where the IEC 60364-4-42:2010+AMD1:2014 comes into play, stating that residual current monitors may be used in conjunction with a circuit breaker to avoid electrically ignited fires due to insulation faults to shut down the system if residual current protective devices (RCDs) are ruled out for technical reasons.

As a result, it is strongly advised to use residual current monitors in accordance with the IEC 62020 in order to exploit all the benefits you can achieve with these devices.


Danisense RCMH070IB+ Residual Current Monitoring


Other Current Transducers from Danisense.

Voltage Output Models

Model Range AC Current DC Current Bandwidth OVERALL ACCURACY DC-10Hz @ 25°C Output Ratio Output Connections Price
DS50UB-1V 100A 50Arms 75A >500kHz 121ppm 1V / 50A BNC Plse Call
DS50UB-10V 55A 36Arms 50A >500kHz 149ppm 10V / 50A BNC Plse Call
DS200UB-1V 330A 200Arms 300A >500kHz 60ppm 1V / 200A BNC Plse Call
DS200UB-10V 220A 140Arms 200A >500kHz 54ppm 10V / 200A BNC Plse Call
DS300UB-10V 330A 210Arms 300A >500kHz 45ppm 10V / 300A BNC Plse Call
DS400UB-10V 440A 280Arms 400A >500kHz ??? 10V / 400A BNC Plse Call
DS600UB-1V 950A 600Arms 900A >300kHz 42ppm 1V / 600A BNC Plse Call
DS600UB-10V 660A 424Arms 600A >300kHz 43ppm 10V / 600A BNC Plse Call
DS1000UB-10V 1100A 700Arms 1000A >300kHz 54ppm 10V / 1000A BNC Plse Call
DL2000UB-1V 3000A 2000Arms 3000A >300kHz 50ppm 1/2000V/A BNC Plse Call
DL2000UB-10V 2200A 1414Arms 2000A >300kHz 50ppm 1/200V/A BNC Plse Call
DM1200UB-10V 1320A 850Arms 1200A >300kHz 35ppm 10V / 1200A DSUB9 male & BNC Plse Call
DR5000UX-10V/7500A 8000A 5000Arms 7500A >100kHz 20ppm 1V / 750A Mini XLR Plse Call
DR10000UX-10V 11000A 7000Arms 10000A >100kHz 20ppm 1V / 1kA Mini XLR Plse Call
RCMH070IB+ Plse Call

Current Output Models

Model Range AC Current DC Current Bandwidth OVERALL ACCURACY DC-10HZ @ 25°C Primary / Secondary Ratio Output Connections PRICE
DC200IF 300A 200Arms 300A >500kHz 11ppm 1 : 1000 6.3mm x 0.8mm Faston
DS50ID 150A 50Arms 75A >1MHz 88ppm 1 : 500 DSUB9 Plse Call
DS200ID 370A 200Arms 300A >1MHz 22ppm 1 : 500 DSUB9 Plse Call
DS200ID-CD100 370A 200Arms 300A 1MHz 22ppm 1 : 500 DSUB9 Plse Call
DS200ID-CD1000 370A 200Arms 300A 1MHz 22ppm 1 : 500 DSUB9 Plse Call
DS300ID 500A 300Arms 450A >1MHz 15.5ppm 1 : 1000 DSUB9 Plse Call
DS400ID 600A 400Arms 600A 300kHz 18.17ppm 1 : 2000 DSUB9 Plse Call
DQ500ID 800A 500Arms 750A >300kHz 11ppm 1 : 1750 DSUB9 Plse Call
DS600ID / DQ600ID 1000A 600Arms 900A >500kHz 9.33ppm 1 : 1500 DSUB9 Plse Call
DS600ID-CD100 1000A 600Arms 900A 500kHz 11ppm 1 : 1500 DSUB9 Plse Call
DQ600ID-P1300 1300A 600Arms 900A 300kHz 11ppm 1 : 1500 DSUB9 Plse Call
DQ640ID-B 640A 28 to 452Arms 40A to 640A >300kHz 13ppm Progr 40A-640A DSUB9 Plse Call
DL2000ID 3000A 2000Arms 3000A >300kHz 7ppm 1 : 1500 DSUB / BNC Plse Call
DL2000ID-CB100 3000A 2000Arms 3000A 300kHz 7ppm 1 : 1500 DSUB9 Plse Call
DL2000ID-CD100 3000A 2000Arms 3000A 300kHz 7ppm 1 : 1500 DSUB9 Plse Call
DM1200ID 1800A 1200Arms 1500A 400kHz 11ppm 1 : 1500 DSUB9 Plse Call
DM1200ID-CD3000 1800A 1200Arms 1500A 15kHz 15ppm 1 : 1500 DSUB9 Plse Call
DR5000IM 8000A 5000Arms 8000A >100kHz 4ppm 1 : 2500 4mm Banana Plse Call
DR10000IM 11000A 7000Arms 10000A >100kHz 6ppm 1 : 2500 4mm Banana Plse Call

PCB Mount

Model Measurement Resistor Linearity Error Weight Height PRICE
DP50IP-B Up to 100Ω at full scale 10ppm 250g 32mm Plse Call