RESIDUAL CURRENT MONITORNING (RCM) PREVENT ELECTRICAL FIRE & HAZARDS
                     
RESIDUAL CURRENT MONITORING (RCM)
PREVENT ELECTRICAL FIRE & HAZARDS
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CONTENTS
• What is Residual Current and 
why you should care
• Types of 
Residual Current Monitoring
• Residual Current Monitoring 
Devices
• Janitza APPs and software for 
RCM
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REASONS 
• Insulation Failures
• Bad Practices
• Unsafe Environment
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WHAT IS RESIDUAL CURRENT? 
• Electrical current that occurs in an 
unwanted conductive path
• It flows from either AC or DC circuit in  
equipment to the chassis, or to the 
ground
• Residual currents are typically the result 
of  insulation faults, defective equipment 
and components (power supplies, 
electrical loads) causing outflow-related 
residual currents and stray currents in 
TN-S systems
• RCM classification is based on 
frequency  and waveform of the 
current that they can  detect - Type A, 
Type B, Type B+
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WHY TO USE RCM 
(EARTH LEAKAGE MONITORING)?
Ensure Continuous System Availability
In Market segments with sensitive applications 
(e.g., Critical power locations, Hospitals, Industrial 
Manufacturing), an uninterrupted power system is 
of crucial importance.
• Uninterrupted operation (Increased Uptime & 
Availability) of an installation is only ensured by 
continuous monitoring.
• Continuous Residual Current Monitoring is the only 
method to detect dangerous fault currents at an 
early stage, thereby avoiding damage to the 
power system as well as preventing server or 
production downtimes. Alarm Notification of Leakage Current helps pre-empt 
Breaker Tripping
• RCM measurement in accordance with DIN EN 
62020 offers the most reliable and safe 
alternative wherever the realization of Insulation 
Resistance Measurement or RCDs are not practical 
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PROBLEMS CAUSED BY 
FAULT CURRENTS
• Electric Shock
• Breaker Tripping
• Fire Hazard
• Server and Computer Shutdown 
• Interruption of Communication 
Corrosion in Pipes caused by Leakage Current Damage to the insulation
Networks
• Temperature Rise in Conductors 
resulting in Insulation Breakdown
• Fast Corrosion of Metal Pipes
• Production Shutdown
• VSD / Inverter Faults 
• Sensor Malfunction 
• Overvoltage Problems 
• Overloaded Neutral Conductor Overloaded N Conductor Data Centre Fire Damage
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INSULATION FAILURE-REASONS 
• Natural deterioration due to aging
• Accelerated by excessive heat and 
moisture
• Heat, moisture and dirt are main causes 
of insulation failure
• Chemical deterioration
• Mechanical damage
• Sunlight
• Excessive voltage stresses
RCM - HOW IT WORKS? 
• Conductors (L1, L2, L3, N) of the specific 
measurement point are to be monitored and passed 
through the RCM CT
• In a fault-free system the sum of all currents is 
ZERO, so that in the current transformer no current 
is induced.
• If a fault current is flowing, the current difference 
induces in the differential CT a mA current that is 
detected by our UMG device
• Residual currents are typically the result of 
insulation faults, defective equipment and 
components (power supplies, electrical loads)
Fault Current ≈ 0 Sum >> 0
System = OK Failure in the 
electrical 
system
RCM CT
RCM INSTALLATIONS
Main Incomer Busbar
RCM CT
RCM INSTALLATIONS
Sub Circuits DB
RCM CT
RCM INSTALLATIONS
Sub Circuits DB
RCM CT
RCM INSTALLATIONS
Single Phase Circuits Server Rack
RCM CT
TYPES OF RCM
TYPE A Sinusoidal alternating current 
pulsed direct current
TYPE B Smooth & pulsating direct current as 
well as alternating currents upto 2 kHz.
TYPE B+ Smooth & pulsating direct current as 
well as alternating currents upto 20 
kHz.
TYPES OF RESIDUAL 
CURRENT 
RCM STANDARDS
• Verification Standard IEC 60364-6; • The functioning of the RCM or IMD shall be 
NEW! Revision… Edition 2.0 2016-04 verified.
• When RCM (Earth Leakage Monitoring) 
is installed and operational, there is 
“NO” requirement for Mains Power 
disconnection
• Confirmation of correct rating and 
setting of monitoring devices
Where a circuit is permanently 
monitored by an RCM in accordance INTERNATIONAL STANDARD
with IEC 62020 or an IMD in • Low Voltage electrical 
accordance with IEC 61557-8, it is not installations – 
necessary to measure the insulation Part 6: Verification
resistance if the functioning of the IMD 
or RCM is correct.
ALTERNATIVE FOR RESIDUAL 
CURRENT MONITORING 
Insulation Testing as part of Preventive Maintenance Residual Current Breakers / 
• Both the ends of the cable need to be disconnected and Earth Leakage Relays  
then meggered for finding the insulation • Trip the circuit causing incidents
• Long testing times results in long shutdown times • Tripping is a surprise factor in 
• Cumbersome procedure of disconnecting the terminated the Facility 
cables • No Prediction only Prevention of 
• Periodicity of the tests needs long term planning as well major fire
Insulation Monitors - Online 
• A popular measuring method is to superimpose a 
measuring DC voltage between the phase and PE 
conductor
• This measurement procedure is suitable for monitoring 
conventional AC, 3(N)AC systems. If it is used in AC, 
3(N)AC systems containing galvanically connected DC 
components, these DC currents will distort the 
measurement result.
• Cost prohibitive
BENEFITS OF RESIDUAL CURRENT MONITORING
SIGNALING
AVOID SYSTEM IMPROVE FIRE
INSTEAD OF
FAILURES PROTECTION
SHUTDOWN
MAINTENANCE PREVENT MONITOR HIGHLY
COST PRODUCTION AVAILABLE ENERGY
OPTIMIZATION INTERRUPTION DISTRIBUTION 
S SYSTEMS
RCM – WHERE IS IT USED?
APPLICATIONS
• TN-S Systems • Industrial Manufacturing
• Drive Systems (Frequency • Data Centre & Critical Power 
Converters) Applications
• DC Applications • Power Distribution Busbar
• Hospital & Medical Facilities • Rail Networks
FROM UTILITY INCOMER TO THE FINAL CIRCUIT – OUR RCM DEVICES
MV & LV LV Main Sub-Distribution PDU, Critical Out-going 
Supply (PCC) Distribution Switchboards,  Power Supply Circuits, Final 
Switchboard UPS Outputs Points & Busway Sub-
Chiller Plants Feed Box Measurement & 
Busway Tap-Offs
UMG 512- UMG 509- UMG 801 UMG 96-PA UMG 96RM-E UMG 96RM- RCM 202-AB RCM 201- UMG 20-CM
PRO PRO PN ROGO
 TYPE A RCM DEVICES
UMG 512 PRO CLASS A PQM UMG 509 PRO UMG 96 RM-E UMG 96 RM-PN
 TYPE A RCM DEVICES
UMG 96 PA UMG 806 RCM 201-ROGO
(with RCM module)
 TYPE A RCM DEVICES
UMG 20 CM RCM 202 AB
 TYPE B RCM DEVICES
UMG 96 RM-E UMG 96 PA UMG 96 PQ-L RCM 202 AB
(with RCM module) (with RCM module)
 TYPE B+ RCM DEVICES
UMG 96 PA UMG 96 PQ-L RCM 202 AB
(with RCM module) (with RCM module)
RCM 202-AB 
• Two-channel RCM device for measurement and 
monitoring according to the IEC 62020 standard
• Comprehensive analytical tools
• Up to a maximum residual current of 20 A
• Measurement and monitoring of AC/DC residual 
currents type A/B/B+ in TN and TT systems 
(grounded AC systems)
• Warning and alarm thresholds configurable for 
each channel separately
• RS 485 interface (Modbus)
• Two digital outputs
• Two analogue outputs (interfaces 4 … 20 mA)
• Harmonics up to 20 kHz (Type B+)
GridVis-RCM REPORT
• Analyze and evaluate residual current violations with 
the GridVis RCM report
• Receive statistics regarding threshold violations with 
graphically highlighted overviews
• Setting of up to 4 threshold levels
• Support of dynamic thresholds (RCM measuring 
device configuration!)
• Custom text, customer logo and export in PDF and 
XLS format
• Report creation can be carried out at custom time 
schedule
• Automatically dispatch per E-Mail
RCM ANALYSIS APP
• APP with extensive options for setting limit 
values and analyzing fault currents in detail
• Up to 20 RCM channels can be managed and 
evaluated via a gateway
• The evaluation covers all types of residual 
current with an associated frequency analysis
• For example, 50 Hz, pure DC or high-frequency 
residual currents in the 20 kHz range can be 
displayed individually
• In addition, the application enables the proven 
dynamic limit value formation with Janitza 
energy measuring devices
• Energy measuring devices can be assigned to 
each of the 20 RCM channels and limit values 
can be calculated as a function of power
THANK YOU
Contact us
MESSUNG SYSTEMS PVT. LTD.
501, 502 & 503 Lunkad Sky Vista, Viman Nagar, Pune, India - 411 014.
+91 20 6649 2800 | [email protected]
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