Siemens SENTRON User manual

SENTRON
Technology primer
Residual Current
Protective Devices

Preface
Whether for protecting, switching, monitoring or measuring – low-voltage
circuit protection devices from Siemens perform a wide range of functions
for all applications in the area of electrical installation technology. They
are suitable for use in residential buildings, non-residential buildings or
industrial applications and thus allow you to maintain control over all
electrical circuits.
This is especially important when it comes to selecting and installing the
appropriate residual current protective device. With this primer, we provide
you with a simple tool for perfectly adapting the respective residual
current protective device to the requirements of the electrical installation
in question. Apart from general information on residual current protective
devices, it contains important details regarding installation and use. You
can therefore be assured that you will always choose the right device.

1 Overview 6
2 Introduction 8
3 Protection through residual current protective devices 8
3.1 Additional protection
(previously „Protection against direct contact“) with IΔn ≤ 30 mA 9
3.2 Fault protection (protection against indirect contact) 12
3.3 Fire protection 13
4 Residual current protective devices 14
4.1 Types of residual current protective devices 14
4.1.1 Type AC 16
4.1.2 Type A 16
4.1.3 Type F 16
4.1.4 Type B 16
4.1.5 Type B+ 17
4.2 Classification of residual current protective devices 17
4.3 Basic design and method of operation 19
4.3.1 Type A RCCB 19
4.3.2 SIQUENCE universal current-sensitive RCCB Type B and Type B+ 21
4.4 Features and application areas 22
4.4.1 RCCB 22
4.4.2 RCBO (Type AC/Type A, Type F) 23
4.4.3 SIQUENCE universal current-sensitive RCCB Type B and Type B+ 26
4.4.4 SIQUENCE universal current-sensitive RCBO Type B und Type B+ 30
4.4.5 RC units for installation on miniature circuit breakers 31
4.4.6 SIGRES RCCB (for harsh ambient conditions) 31
4.4.7 Type
Ksuper-resistant 32
4.4.8 Type
Sselective 34
4.4.9 Versions for 50 to 400 Hz 35
4.4.10 Versions for 500 V operational voltage 35
4.4.11 Residual current operated circuit breaker with N-connection
on the left side 35
4.5 Additional components for residual current operated
circuit breakers 36
4.5.1 Remote controlled operating mechanism (RC) 36
Contents

4.5.2 Auxiliary switch 37
4.5.3 Additional components 37
5 Notes on installation and use 38
5.1 General notes 38
5.1.1 Selection of protective devices 38
5.1.2 Use of residual current protective devices 40
5.2 Choosing the right residual current protective device 42
5.2.1 Type A, Type F or Type B/ Typ B+? 43
5.2.2 What protection goal must be achieved? 43
5.2.3 What electrical interference occurs and how is it handled? 44
5.2.3.1 Leakage currents 44
5.2.3.2 High load currents 45
5.2.3.3 Overvoltages and surge current load 46
5.3 Special features regarding the use of SIQUENCE universal
current-sensitive residual current protective devices
(Type B and Type B+) 47
5.3.1 Applications 47
5.3.2 Residual currents at different fault locations, with a frequency
converter (FC) as an example 47
5.3.3 Configuration 52
5.3.4 Causes of excessive leakage currents and possibilities of
reducing them 53
5.4 Back-up protection 55
5.5 Protection against thermal overload 57
5.6 Troubleshooting 58
5.7 4-pole residual current operated circuit breakers in a
3-pole network 59
6 Residual current monitoring devices (RCM) 59
7 Outlook 61
8 Source specified 62
9 Appendix 63
10 List of figures and tables 74

6
Overview
Residual current operated circuit
breaker (RCCB)
SIQUENCE residual current
operated circuit breaker (RCCB)
SIQUENCE residual current operated
circuit breaker with overcurrent
protector (RCBO)
5SM3 / 5SV
• Type AC, Type A and Type F
•
I
n= 16 … 125 A
•
I
∆n = 10 mA … 1 A
• 2-pole (1+N) and 4-pole (3+N)
• N connection at left and right
• SIGRES for harsh ambient
conditions
• Version Kand S
• 500 V version
• 50 … 400 Hz version
5SM3
• Type B, Type B+
•
I
n = 16 … 80 A
•
I
∆n = 30, 300 and 500 mA
• 2-poe (1+N) and 4-pole (3+N)
• Version Kand S
• including SIGRES functionality
5SU1
• Type B, Type B+
•
I
n = 100 ... 125 A
•
I
∆n = 30, 300 mA and 1A
• 4-pole
• Circuit breaker characteristic
C and D
• Rated switching capacity 10 kA
• Version Kand S
1. Overview

7
RC unit for combination with a
miniature circuit breaker
RCBOs; combination units
Residual current monitoring
devices (RCM)
5SM2
• For mounting on a miniature
circuit breaker
• Combined electric shock and
line protection
• Type AC, Type A and Type F
•
I
n = 0.3 … 100 A
•
I
∆n = 10 mA … 1 A
• 2-, 3- and 4-pole
• Version Kand S
5SU1
• Combined electric shock and
line protection
• Type AC, Type A and Type F
•
I
n = 6 … 40 A
•
I
∆n = 10 … 300 mA
• Circuit breaker characteristic B and C
• Rated switching capacity 4.5 kA,
6 kA and 10 kA
• 1+N-pole, 2-pole
• N connection at right and left
5SV8
• Residual current monitoring
• Type AC and Type A
•
I
∆n = 0.03 ... 30 A
• Response time 0.02 ... 10 s
• Summation current transformer
20 ... 210 mm

8
Introduction
2. Introduction
When dealing with electricity, safety has top priority. Every electrician must be
particularly conscientious when safety is concerned and must apply the required
protective measures correctly. In consumer’s installations, residual current pro-
tective devices must be given unreserved preference over alternative protective
devices.
In addition to fault protection (protection in cases of indirect contact), residual
current protective devices with rated residual currents up to 30 mA also provide
“additional protection” in cases of direct contact. Fires caused by ground-fault
currents can also be prevented at a very early stage.
In many cases, the DIN VDE standards require the use of residual current protec-
tive devices. Electricians should therefore make sure that they are fully informed
about residual current protective devices.
In addition to information on the protective effect of residual current protective
devices, an understanding of how the devices function is also conveyed. In order
to optimally adapt the use of residual current protective devices to the require-
ments of the electrical installation, the functionality of the different versions of
residual current protective devices is discussed and the user is given practical
installation and application tips.
3. Protection through residual current protective devices
The basic prerequisite for use of a residual current protective device in order to
automatically disconnect the power supply as a protective measure is that an
appropriately grounded protective conductor is connected to the system com-
ponents and equipment to be protected. Current can then pass through a human
body only when two faults occur (interruption of the PE conductor in addition to a
fault in the insulation) or when there is unintentional contact between live parts.

9
Protection through residual current protective devices
3.1 Additional protection (previously „Protection against direct contact“)
with IΔn≤30mA
Additional protection is understood to mean protection which takes effect if there
is direct contact of a human body with a part normally live during operation in
the event of basic and/or fault protection failing. When a human body touches
live parts, two resistors connected in series determine the intensity of the  owing
current – the internal resistance of the human body Rmand the transfer resistance
of the location Rst ( gure1).
Direct contact
In² 30 mA
RBRst
Rm
IM
Figure 1: Protection against direct contact
In order to consider the accident properly, the worst case scenario where the
transfer resistance of the location is near zero must be assumed.

10
The resistance of the human body depends on the current path and the contact
resistance of the skin. Measurements have shown e.g. approximately 1,000 Ω
for the  ow of current from hand to hand or from hand to foot. Under these
assumptions, a touch voltage of 230 V results in a dangerous shock current of
230 mA. Figure 2 shows the current intensity/exposure time curves in relation to
the physiological reactions of the human body. Dangerous current intensities and
exposure times are those which reach as far as zone 4, as they can cause death
due to ventricular  brillation. It also shows the tripping ranges of the residual
current protective devices with rated residual currents of 10 mA and 30 mA. It
also shows the maximum permissible tripping times according to VDE 0664-10.
As can be seen from the tripping curves, residual current protective devices do
not limit the intensity of the residual current but provide protection due to fast
disconnection of the power and therefore a minimal time of exposure to the
current.
Protection through residual current protective devices
Figure 2: Effects of 50/60 Hz alternating current on the human body
Protection against direct contact (additional protection) with IΔn≤30mA
Zone ①: Exposure is normally imperceptible.
Zone ②: There are generally no injurious effects or muscle spasms.
Zone ③: Muscle cramps can occur. There is normally no danger of
ventricular  brillation.
Zone ④: Ventricular  brillations may occur.
IM
10 mA 30 mA
ms
mA
t
10.000
1.000
100
100
0,1 110 100 1.000 10.000

11
The tripping curve of residual current protective devices with a rated residual cur-
rent of IΔn ≤ 10 mA is in zone 2 below the release limit. Medically damaging effects
and muscle cramps do not usually occur (see gure 2). They are therefore suitable
for sensitive areas, such as bathrooms.
Residual current protective devices with a rated residual current of IΔn ≤ 30 mA
fulll the conditions for additional protection against electric shock (see gure 2):
• in the event of unintentional, direct contact with parts that are live when
operational (e.g. failure of the basic insulation, operation for other than the
intended purpose, ineffective basic protection)
• in the event of carelessness on the part of the user (e.g. use of defective
equipment, incorrectly repaired components and equipment)
• in the event of contact with defective live parts (e.g. loss of protection
against faults due to interruption of the protective conductor)
The use of residual current protective devices with a rated residual current of up
to 30 mA has proven to be effective as additional protection in the event of failure
of the basic protection precautions (protection against direct contact) and/or fault
protection precautions (protection against indirect contact) as well as in the event
of carelessness on the part of the user when using electrical equipment. However,
this should not be the only way of providing protection against electric shock.
This does not replace the need for further protective measures as required by
DIN VDE 0100-410.
The requirement for „additional protection“ with residual current protective
devices according to sections 411.3.3 and 415.1 of DIN VDE 0100-410 does not
mean that how this protection is used is up to the user. This additional protec-
tion can be required in conjunction with other protection measures under certain
external inuences and in certain special areas.
In several parts of the standards of sections 4 and 7 of DIN VDE 0100, this additio-
nal protection is required or expressly recommended (see appendix). Some im-
portant requirements are explained below in more detail as examples.

12
In the generally applicable standard for protection against electric shock
(DIN VDE 0100-410:2007-06, the use of residual current protective devices with
a rated residual current of ≤ 30 mA is required as additional protection for
• all socket outlets with a rated current of ≤ 20 A if they are intended for use by
non-experts and for general use
• nal circuits for portable items of equipment used outdoors with a rated current
of ≤ 32 A.
Note:
In DIN VDE 0100-410:06-2007, two exceptions from these requirements are
indicated but they are not usually applicable in the majority of applications.
The requirement of the standard for additional protection can be avoided only
in the case of socket outlets which are only used by qualied electricians and
persons who have received appropriate technical instruction (e.g. in electrical
workshops) or if it has been ensured that the socket outlet is only used per-
manently for a „specic item of equipment“.
According to standard DIN VDE 0100-723:2005-06 „Requirements for special
installations, locations or plants – classrooms with experimental equipment“,
Type B residual current protective devices with a rated residual current of
≤ 30 mA must be used for supplying power to the experimental equipment and
its circuits in TN or TT systems.
3.2 Fault protection (previously “Protection against indirect contact”)
Fault protection is understood to mean the contact of a human body with a part
that is not live in operation but is electrically conductive. In these cases, the de-
mand is for automatic disconnection of the power supply when a fault can pose
a risk due to the intensity and duration of the touch voltage.
Residual current protective devices with rated residual currents of over 30 mA
are also suitable for this purpose. The tripping conditions must be complied with
to achieve the protective effect. In addition, the dangerous touch voltage must
not be present for an impermissible length of time, taking into consideration the
grounding resistance and the rated residual current.
Protection through residual current protective devices

13
Indirect contact
Figure 3: Protection against indirect contact
Rst
Rm
IM
RB
3.3 Fire protection
DIN VDE 0100-482 requires measures for the prevention of  res which can be
caused by insulation faults in “locations exposed to  re hazards”. This stipulates
that cables and conductors in TN and TT systems must be protected by means of
residual current protective devices with a rated residual current of IΔn ≤ 300 mA.
This does not include mineral-insulated cables and busbar systems.
In applications in which resistive faults can cause a  re (e.g. radiant ceiling heating
with panel heating elements), the rated residual current must be IΔn = 30 mA. The
 re protection provided by residual current protective devices, however, should
not be limited to locations exposed to  re hazards but should always be provided.

14
Residual current protective devices
4. Residual current protective devices
4.1 Types of residual current protective devices
Residual current protective devices are distinguished from one another in respect
of their suitability for detecting different forms of residual current (table 1).
Residual current with different waveforms can occur depending on the electronic
switching in the circuit. Since residual current protective devices differ in their
suitability for detecting residual current waveforms, the relevant load input circuit
must be taken into account when such a device is chosen.
Table 2 shows electronic circuits and their possible load and residual currents,
along with the suitable types of residual current protective device in each case.
According to the function of RCCBs in various types
Current
type
Type AC Type A Type F Type B Type B+ Tripping
current
0.5 – 1.0 IΔn
0.35 – 1.4 IΔn
Lead angle
135°
0.11 – 1.4 IΔn
max. 1,4 IΔn
+ 6 mA (Type A)
+ 10 mA (Type F)
+ 0,4 IΔn (Type B/B+)
0.5 – 1.4 IΔn
0.5 – 2.0 IΔn
~
Table 1: Classication of residual current protective devices into different
types with tripping ranges

15
Table 2: Possible residual current waveforms and suitable residual current
protective devices
Suitable
RCD type Circuit Load current Residual current

16
Residual current protective devices
4.1.1 Type AC
Type AC residual current protective devices are suitable only for detecting
sinusoidal AC residual currents (see circuits 1 to 3 in table 1). This device type
is not authorized in every country (e.g. Germany as per DIN VDE 0100-530) for
residual current protection and cannot carry the VDE mark of conformity.
4.1.2 Type A
Type A residual current protective devices detect pulsating DC residual currents
in addition to sinusoidal AC residual currents. This type of device is the most com-
monly used pulse currentsensitive residual current protective device in Germany.
It can therefore also handle the residual current waveforms which can occur in the
power supply units of single-phase loads with electronic components (e.g. ECG,
dimmer switches). Smooth DC residual currents up to 6 mA do not affect the trip
properties unacceptably. This type of residual current protective device is suitable
for electronic equipment with input current circuits 1 to 6 in table 2.
4.1.3 Type F
Type F residual current protective devices detect all residual current types as do
Type A. Additionally, they are suitable for detecting residual currents from mixed
frequencies of up to 1 kHz. This will also be able to cope with the possible residual
current waveforms on the output side of single-phase connected frequency con-
verters (e.g. in washing machines, pumps). Smooth DC residual currents up to
10 mA do not affect the trip properties unacceptably. Type F residual current
protective devices additionally have short-time delayed tripping and enhanced
current withstand capability. They are suitable for electronic equipment with
input current circuits 1 to 7 in table 2.
4.1.4 Type B
In addition to detecting residual current waveforms of Type F, residual current
protective devices of Type B are used to detect smooth DC residual currents.
Residual current protective devices of this type are suitable for use in 50/60 Hz
three-phase AC systems, but not in DC voltage systems or where frequencies
differ from 50/60 Hz as on the output side of frequency converters. They can be
used for all input current circuits listed in table 1, i.e. also for those identied
with numbers 8 to 13. Tripping values dened up to 2 kHz.
~

17
4.1.5 Type B+
The same conditions apply for Type B+ residual current protective devices as for
Type B residual current protective devices. It is only that the frequency range for
the detection of residual currents is extend to 20 kHz: The device will trip within
this frequency range below 420 mA.
4.2 Classicationofresidualcurrentprotectivedevices
Residual current protective devices are classied according to their various
versions (see gure 4).
• RCD is the generic term for all types of residual current protective device.
• RCCBs are residual current operated circuit breakers without integral overcurrent
protection known in Germany as Fehlerstrom-Schutzschalter (FI-Schutzschalter).
• RCBOs are devices which feature an integrated overcurrent protection unit for
overload and short-circuit protection in addition to protection against residual
currents. Another version in this device group is the residual current unit
(RC unit). The customer can then mount the miniature circuit breaker versions
suitable for a particular application (characteristic, rated current, switching
capacity) on these RC units. Once assembled, these devices perform the same
functions as an RCBO. The RC unit provides residual-current detection but has
no contacts of its own; in the event of a fault, it trips the miniature circuit
breaker which opens the contacts and interrupts the circuit.
Given their tripping conditions, only versions of RCCBs and RCBOs which are inde-
pendent of the supply voltage are approved for AC residual currents and pulsating
residual currents (Type A) in Germany and in most other European countries as a
means of providing protection with disconnection of the supply. Only such RCCBs
and RCBOs are permitted to bear the VDE mark of conformity.
• CBRs are miniature circuit breakers with residual current protection in accordance
with EN 60947-2 (VDE 0660-101), appendix B. In this case, a residual-current
detector is permanently installed on a miniature circuit breaker, thus ensuring
residual current protection.
• MRCDs are modular devices, i.e. separate modules are provided for residual
current detection (via current transformers), evaluation and tripping (via
miniature circuit breakers) (in accordance with EN 60947-2 (VDE 0660-101),
appendix M).

18
Residual current protective devices
CBRs and MRCDs are especially intended for applications with higher rated
currents (> 125 A).
• PRCDs are portable residual current protective devices which are integrated,
for example, in connectors or in multiple socket outlets.
• SRCDs are, according to DIN VDE 0662, non-portable residual current protective
devices which are integrated in a socket outlet or form a single unit with a
socket outlet.
PRCDs and SRCDs can be used to raise the level of protection for applications in
which the required protective measure is ensured in some other manner. They are
not permissible as a protective measure with disconnection of the supply.
Figure 4: Classi cation of residual current protective devices (RCDs)
RCD
Residual current device
RCCB RCBOCBR PRCD SRCD
Modular residual current devices (without integral current breaking devices)
Circuit breakers incorporating residual current protection
Residual current operated circuit breaker *
Residual current operated circuit breaker with overcurrent protector *
Portable-residual current protective device
Socket-outlet-residual current protective device
* System voltage-independent detection and tripping
Protection objectives:
• Additional protection with rated residual
current IΔn ≤ 30 mA
• Fault protection with rated residual current
IΔn > 30 mA
• Fire protection with rated residual current
IΔn ≤ 300 mA
All residual current protective devices comply
with the DIN VDE standards
Not for protective
measure according to
DIN VDE 0100-410,
only local protection
level increase
MRCD

19
4.3 Basic design and method of operation
4.3.1 RCCB Type A
A residual current operated circuit breaker of Type A essentially consists of the
following function groups:
• Summation current transformer for residual current detection
• Tripping circuit with components for evaluation and holding magnet release
for converting the electrical measured variable into a mechanical latch release
• Breaker mechanism with contacts
Note:
With the exception of the tripping circuit, the design of the Type AC and Type F
RCCBs is identical to that of Type A.
The summation current transformer comprises all conductors of the circuit to be
protected, including the neutral conductor. In a fault-free system, the magnetic
effects of the current-carrying conductors are cancelled out in the summation
current transformer. There is no residual magnetic eld which could induce
voltage onto the secondary winding of the transformer.
A residual magnetic eld remains in the transformer core only if residual current
is owing, e.g. due to an insulation fault in the system to be protected (from
the electrical point of view, downstream of the residual current operated circuit
breaker). This generates a voltage in the secondary winding, effecting discon-
nection of the circuit with the excessive touch voltage by means of the holding
magnet release and the breaker mechanism (see gure 5).
Holding magnet
release
Mechanics of the
protective device Secondary winding
Summation current transformer
Test button
Test resistor
Figure 5: Schematic representation of a residual current operated circuit breaker

20
Residual current protective devices
In accordance with the device standard EN 61008-1 (VDE 0664-10), the device
must disconnect within 300 ms at the rated residual current. In accordance with
the product standard applicable in Germany, Type A and Type F residual current
operated circuit breakers must function independently of supply voltage and
auxiliary voltage in all function groups (detection, evaluation, disconnection) in
order to achieve a consistently high level of reliability of the device protection
function.
The function of the trip element, which works independently of the supply or
auxiliary voltage, is shown in gure 6.
Immediately above the permanent magnet lies a magnetic shunt whose primary
task is to stabilize the permanent magnet‘s magnetic ux. On one pole core, there
is an excitation winding, which is connected to the secondary winding of the
summation current transformer. If there is a ground fault in the main circuit, a
voltage is induced in the secondary winding of the summation current transformer.
The left part of the illustration shows the rest position when the system is in a
fault-free state. The permanent magnet drives a magnetic ux between two cores
of magnetically soft material and stabilizes the armature through counteraction
of a spring force. When a voltage is generated in the secondary winding of the
transformer (middle part of the illustration), this voltage drives a current through
the excitation winding. This generates a second magnetic ux. The effect of the
permanent magnetic eld is cancelled out in a half-wave by the second magnetic
eld (righthand part of the illustration).
Figure 6: Principle of operation of a holding magnet release