Siemens SENTRON User manual

SENTRON
www.siemens.com/rccb
Residual current
protective devices
Technology primer
Edition 06/2018

2

3
Be it protecting, switching, measuring or monitoring – components for
low-voltage power distribution from Siemens offer just the right device
for all applications in the electrical installation field. Whether for use in
industry, infrastructure or buildings, these products guarantee a maximum of
flexibility, ease of use and safety.
So you can keep the entire power supply safely under control.
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
circuit breaker 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 are therefore
sure of always selecting the right device.
Preface

4
1. Product portfolio 6
2. Introduction 8
3. Protection through residual current protective devices 9
3.1 Additional protection with In ≤ 30 mA
(previously “Protection against direct contact”) 9
3.2 Fault protection (previously “Protection against indirect contact”) 13
3.3 Fire protection 14
4. Residual current protective devices 15
4.1 Types of RCCBs 15
4.1.1 Type AC 17
4.1.2 Type A 17
4.1.3 Type F 17
4.1.4 Type B 17
4.1.5 Type B+ 18
4.2 Classification of residual current protective devices 18
4.3 Basic design and method of operation 21
4.3.1 Type A RCCB 21
4.3.2 SIQUENCE universal current-sensitive RCCB Type B and Type B+ 24
4.4 Features and application areas 25
4.4.1 RCCB 25
4.4.2 RCBO Type AC, Type A and Type F 26
4.4.3 SIQUENCE universal current-sensitive RCCB Type B and Type B+ 29
4.4.4 SIQUENCE universal current-sensitive RCBO Type B and Type B+ 34
4.4.5 RC units for installation on miniature circuit breakers 35
4.4.6 SIGRES RCCBs (for harsh ambient conditions) 36
4.4.7 Type
Ksuper-resistant 37
4.4.8 Type
Sselective 39
4.4.9 Versions for 50 to 400 Hz 40
4.4.10 Versions for 500 V operational voltage 40
4.4.11 RCCB with left-side N connection 40
4.5 Additional components for RCCBs 41
4.5.1 Remotely controlled mechanism (RC) 41
4.5.2 Auxiliary switches 43
4.5.3 Additional components 43
Contents

5
5. Notes on installation and use 44
5.1 General notes 44
5.1.1 Selection of protective devices 44
5.1.2 Use of residual current protective devices 46
5.2 Choosing the right residual current protective device 48
5.2.1 Type A, Type F or Type B / Type B+? 49
5.2.2 What protection goal must be achieved? 49
5.2.3 What electrical interference occurs and how is it handled? 50
5.3 Special features regarding the use of SIQUENCE universal current-sensitive
RCCBs (Type B and Type B+) 53
5.3.1 Applications 53
5.3.2 Residual currents at various fault locations, with a frequency
converter (FC) as an example 54
5.3.3 Configuration 61
5.3.4 Causes of excessive leakage currents and possibilities of reducing
them 62
5.4 Back-up protection 64
5.5 Protection against thermal overload 66
5.6 Troubleshooting 67
5.7 4-pole RCCBs in a 3-pole network 68
6. MRCDs and RCMs 69
6.1 Modular residual current devices (MRCDs) 69
6.2 Residual current monitoring devices (RCMs) 70
7. Outlook 73
8. Sources 74
9. Appendix 75
9.1 Key terms and definitions (according to DIN VDE 0100-200) 75
9.2 Power systems and protective devices 78
9.2.1 TN system 79
9.2.2 TT system 80
9.2.3 IT system 82
9.2.4 Summary 83
9.3 Key terms and definitions for specifying the switching capacity 84
9.4 Installation regulations for electrical installations with residual current
protective devices 85
10. List of figures and tables 87

6
Product portfolio
1. Product portfolio
Residual current circuit breaker
(RCCB) 5SM3 / 5SV
• Type AC, Type A and Type F
• In= 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 version for harsh ambient
conditions
• Version Kand S
• Version for 500 V
• Version for 50 … 400 Hz
SIQUENCE residual current circuit
breaker (RCCB) 5SM3/5SV3
• Type B, Type B+
• In= 16 … 80 A
• In = 30, 300 and 500 mA
• 2-pole (1+N) and 4-pole (3+N)
• Version Kand S
• including SIGRES functionality
SIQUENCE residual current breaker
with overcurrent protection (RCBO) 5SU1
• Type B, Type B+
• In= 100 … 125 A
• In = 30, 300 mA and 1 A
• 4-pole
• Circuit breaker characteristic
C and D
• Rated switching capacity 10 kA
• Version Kand S

7
RC unit for combination with a
miniature circuit breaker 5SM2
• For mounting on a miniature
circuit breaker
• Combined electric shock and line
protection
• Type AC, Type A and Type F
• In= 0.3 … 100 A
• In = 10 mA … 1 A
• 2-, 3- and 4-pole
• Version Kand S
RCBOs;
combination units 5SU1
• Combined electric shock and line
protection
• Type AC, Type A and Type F
• In= 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
Residual current monitoring
devices (RCM) 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
protective devices must be given unreserved preference over alternative protective
devices.
In addition to fault protection (protection against indirect contact), RCCBs 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 protective
devices. Electricians should therefore make sure that they are fully informed about
RCCBs. In addition to information on the protective effect, an understanding of
how the devices function is also conveyed.
In order to optimally adapt the use of the devices to the requirements of the
electrical installation, the functionality of the different versions of RCCBs is
discussed and the user is given practical installation and application tips.

9
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
components 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.
3.1 Additional protection with IΔn ≤ 30 mA
(previously “Protection against direct contact”)
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. If a person directly touches live parts,
two series-connected resistors determine the level of the current – the internal
resistance of the person Rmand the transfer resistance of the location Rst; see
Fig. 1.

10
Protection through residual current protective devices
Direct contact
IΔn≤30mA
RBRst
Rm
IM

Fig. 1: Protection against direct contact: Additional protection means measures
to protect against direct contact with an active part that is energized
during operation.
For a proper assessment of the accident risk, it must be assumed that the contact
resistance of the location is virtually zero.
The resistance of the human body depends on the current path and the contact
resistance of the skin. Measurements have shown, for example, that a current
path of hand/hand or hand/foot has a resistance of approx. 1000 . Under these
assumptions, a touch voltage of 230 V would produce a dangerous shock current
of 230 mA. Fig. 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 , as they can cause death
due to ventricular fibrillation. It also shows the tripping ranges of the residual
current protective devices with rated residual currents of 10 mA and 30 mA. The
maximum permissible tripping times according to VDE 0664-10 are also depicted.
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.

11
Protection against direct contact (additional protection) with IΔn ≤ 30 mA
IM
10 mA 30 mA
ms
mA
t
10,000
1,000
100
100
0,1 110100 1,00010,000
Fig. 2: Effects of 50/60 Hz alternating current on the human body
Zone : Exposure is normally imperceptible.
Zone : There are generally no injurious effects or muscle spasms.
Zone : Muscle cramps can occur. There is normally no danger of
ventricular fibrillation.
Zone : Ventricular fibrillations may occur.
Residual current protective devices with a rated residual current of In ≤ 10 mA
have a tripping characteristic in zone , i.e. below the let-go current. There are
generally no injurious effects or muscle spasms. They are therefore suitable for
sensitive areas, such as bathrooms.

12
Protection through residual current protective devices
Residual current protective devices with a rated residual current of In ≤ 30 mA
meet the conditions for additional protection against electric shock (see Fig. 2):
• In the case of accidental direct contact with parts that are live under operating
conditions (e.g.: failure of the basic insulation, operation for other than the
intended purpose, ineffective basic protection)
• In the case of negligence on the part of the user (e.g. use of defective devices,
inexpert repairs to systems and/or equipment)
• In the case of contact with faulty live parts (e.g. failure of fault protection in
the event of 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 protection can
be required in conjunction with other protection measures under certain external
influences and in certain special areas.
In several parts of the standards for Groups 4 and 7 of DIN VDE 0100, this
additional protection is required or explicitly recommended (see „Appendix“).
Some important requirements are explained below in more detail as examples.
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.
• For branch circuits for portable items of equipment used outdoors with a rated
current of ≤ 32 A.

13
Note
While DIN VDE 0100-410:06-2007 specifies two exceptions to these require-
ments, these are not generally applicable to 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 qualified 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 permanently for a “specific 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 measures to protect against the contact of
a human body with a part that is not live in operation but is electrically conductive.
In these cases, the demand 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.

14
Protection through residual current protective devices
Indirect contact
Rst
Rm
IM
RB
Fig. 3: Protection against indirect contact: Fault protection is understood to
mean measures to protect against the contact of a human body with a
part that is not live in operation but is electrically conductive.
3.3 Fire protection
DIN VDE 0100-482 requires measures for the prevention of fires which can be
caused by insulation faults in “locations exposed to fire 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 In ≤ 300 mA.
This does not include mineral-insulated cables and busbar systems.
In the case of applications where resistance-related faults may cause a fire
(e.g. ceiling heating with panel heating elements), the rated residual current must
be In = 30 mA. The fire protection provided by residual current protective devices,
however, should not be limited to locations exposed to fire hazards but should
always be provided.

15
4. Residual current protective devices
4.1 Types of RCCBs
Residual current circuit breakers are distinguished from one another in respect of
their suitability for detecting different forms of residual current (Table 1).
Proper function of the RCCBs
Current
wave-
form
Type
AC
Type
A
Type
F
Type
B
Type
B+
Tripping
current
• • • • • 0.5 ... 1.0 In
• • • • 0.35 ... 1.4 In
• • • • Start angle 135°
0.11 ... 1.4 In
• • • • max. 1.4 In
+6 mA (Type A)
+10 mA (Type F)
+0.4 In (Type B/B+)
• • • 0.5 ... 1.4 In
• • 0.5 ... 2.0 In
Table 1: Classification of RCCBs into different types with tripping ranges
Residual current with different waveforms can occur depending on the electronic
switching in the circuit. Since RCCBs 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 RCCB in each case.

16
Residual current protective devices
Suitable
RCCB type
Circuit Load current Residual current
Table 2: Possible residual current waveforms and suitable RCCBs

17
4.1.1 Type AC
a
Type AC RCCBs are suitable only for detecting sinusoidal AC residual currents
(see circuits 1 to 3 in Table 2). 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 RCCBs detect pulsating DC residual currents in addition to sinusoidal AC
residual currents. This type of device is the most commonly used pulse current-
sensitive 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 RCCB is suitable for electronic equipment with input
circuits 1 to 6 in Table 2.
4.1.3 Type F
Type F RCCBs detect all residual current types, as do Type A. Additionally, they
are suitable for detecting residual currents with mixed frequencies up to 1 kHz.
They will also be able to cope with the possible residual current waveforms on
the output side of single-phase connected frequency converters (e.g. in washing
machines, pumps). Smooth DC residual currents up to 10 mA do not affect the
trip properties unacceptably. Type F RCCBs additionally have short-time delayed
tripping and an enhanced current withstand capability. They are suitable for
electronic equipment with input circuits 1 to 7 in Table 2.
4.1.4 Type B
In addition to detecting residual current waveforms of Type F, RCCBs 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, such as on the
output side of frequency converters. They can be used for all input circuits listed
in Table 2, i.e. also for those identified with numbers 8 to 13. Tripping values are
defined up to 1 kHz.

18
Residual current protective devices
4.1.5 Type B+
The same conditions apply for Type B+ RCCBs as for Type B residual current
protective devices. It is only that the frequency range for the detection of residual
currents is extended to 20 kHz: The device will trip within this frequency range
below 420 mA.
4.2 Classification of residual current protective devices
Residual current protective devices are classified according to their various versions
(see Fig. 4).
• RCD is the generic term for all types of residual current protective devices.
• RCCBs are residual current 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
independent 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.

19
• 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).
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.

20
Residual current protective devices
RCD
RCCB RCBOCBR PRCD SRCDMRCD
Protection objectives
• Additional protection with rated residual
current In ≤ 30 mA
• Fault protection with rated residual current
In > 30 mA
• Fire protection with a rated residual current of
In ≤ 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 enhancement of
protection level
Fig. 4: Classification of residual current protective devices (RCDs)
Modular residual current devices (without integral current breaking devices)
Circuit breakers incorporating residual current protection
RCCB *
RCBO *
Portable residual current protective device
Socket-outlet residual current protective device
* System voltage-independent detection and tripping