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CIRCUIT PROTECTION
591
RATING SPECIFICATION
DOUBLE POLE, 2 MODULE
RATING RCBO TRIPPING CURRENT
LIST NO.
16A, 110V
10mA
6016s
16A, 110V
30mA
6416s
16A, 230V
10mA
6316s
16A, 230V
30mA
5716s
32A, 110V
30mA
6032s
32A, 230V
30mAs
6730s
40A, 230V
30mA
5740s
63A, 230V
30mA
5760s
63A, 230V
100mA
6160s
63A, 230V
300mA
5860s
80A, 230V
30mA
5780s
80A, 110V
30mA
6080s
80A, 230V
300mA
5880s
80A, 230V
100mA
6180s
100A, 230V
30mA
7700s
100A, 230V
100mA
6600s
100A, 230V
300mA
7800s
DOUBLE POLE, PULSATING D.C.,
FAULT CURRENT SENSITIVE, 2 MODULE
16A, 230V
10mA
6216s
16A, 230V
30mA
6716s
32A, 230V
30mA
6630s
40A, 230V
30mA
5640s
63A, 230V
30mA
5660s
TIME DELAYED, 2 MODULE
80A, 230V
100mA
6980s
100A, 230V
100mA
6400s
FOUR POLE, 4 MODULE
25A, 230/400V
30mA
6425s
40A, 230/400V
30mA
6440s
40A, 230/400V
100mA
6240s
63A, 230/400V
30mA
6463s
63A, 230/400V
100mA
6363s
63A, 230/400V
300mA
6263s
FOUR POLE, PULSATING D.C.,
FAULT CURRENT SENSITIVE, 4 MODULE
40A, 230/400V
30mA
6640s
Installation
Sentry RCDs must never be used as the sole
method of basic protection, but are invaluable in
providing supplementary protection in high risk
environments where damage may occur.
Sentry Technical
Industrial 10kA Residual Current Devices (RCDs)
Application
The choice of the most suitable RCD for a particular application should take into
account the following considerations:
1. Sensitivity
10mA RCDs offer a high degree of protection against electrocution in an accidental
shock hazard situation. They are of particular value in a high risk area where
resistances external to the body are likely to restrict the earth fault current flowing
through the body to less than 30mA and where 110V supply is being used.
30mA RCDs offer a high degree of protection in an accidental shock hazard
situation and are by far the most popular sensitivity used in the United Kingdom. In
a shock situation, the current flowing through the human body at 240V 50Hz could
be between 80 and 240mA, depending on the resistance of the body in question.
To ensure that there are no harmful physiological effects in such a situation, it is
necessary for the RCD to operate within 300mS at 30mA and 40mS at 150mA.
As the Sentry RCD typically operates well below these times, it clearly more than
satisfies this requirement.
100mA RCDs may, in some circumstances, provide protection against electrocution
in an accidental shock hazard situation. However, it is important to note that there is
a likelihood that the earth fault current may be below the sensitivity of the RCD. This
becomes increasingly likely if additional resistances to that of the human body are in
the current path.
300mA RCDs provide protection against the risk of fire only. They do not provide
protection against electrocution in an accidental shock hazard situation. A typical
application would be lighting circuits where it is deemed that the risk of electric
shock is small.
It is important to note that a current of less than 500mA flowing in a high resistance path
is sufficient to bring metallic parts to incandescence and, potentially, initiate a fire.
2. Requirements of the IEE Wiring Regulations BS 7671
RCDs may be used to provide additional protection against both fault protection and
basic protection.
Fault Protection
Defined as protection against electric shock under single fault conditions.
Effective earthing in conjunction with automatic disconnection should always be
employed to protect against the effects of fault protection. The provision of a low
resistance path back to the supply from the fault should ensure that the overcurrent
device operates before damage occurs. This is the earth fault loop impedance.
In circumstances where the earth fault loop impedance in the circuit is too high
to ensure operation of the overcurrent device, then the IEE Wiring Regulations
allow the installation of an RCD. To comply with the Regulations, the earth loop
impedance of the circuit (in ohms), multiplied by the rated tripping current of the
RCD (in amperes) must not produce a value greater than 50. With this in mind, the
maximum values of earth loop impedance permissible when installing an MK Sentry
RCD are as follows:
50 50
Z
s
(max) = ——– = ——– = 1667 Ohms
l
∆
n 0.03
Rated Tripping Current of RCD
Maximum Permissible Earth Fault Loop
Impedance
10mA
5000 Ohms
30mA
1667 Ohms
100mA
500 Ohms
300mA
166 Ohms
RCD’s are further specified for fault protection on TT systems (Regulation 411.5.2, 411.5.3 apply)