LED (H) Range
13
When the autotest detects that the differential protection is not valid, it cuts off and diagnoses. In this way, one is totally
assured of the constant validity of the extraordinary degree of protection afforded by this differential and the fact that it
makes for easy inspection and guarantees that the ruling legislation is complied with at all times.
If the autotest detects an anomaly, it cuts off and emits a diagnosis by means of the static “I
N
”LED lit up. When the
anomaly has disappeared, the unit resets.
Redundant cut-off devices
As a redundant security measure, the unit has a built-in
double cut-off device
for the ancillary MCB, viz.:
Cut-off device #1, by means of a very high-speed tripping coil
Cut-off device #2, by means of a built-in motor-drive
Moreover, in order to command the double cut-off device, the unit has two independent cut-off circuits, viz.:
1 – Very high-speed cut-off circuit for the MCB by means of a coil. It has its own exclusive built-in energy storage which
permits it to disconnect the MCB even when there is no mains supply.
2 - Cut-off circuit by means of a motor. It has its own exclusive built-in energy storage which permits it to
disconnect and connect the MCB even when there is no mains supply.
CHAPTER 3
- Description of Protections
Differential protection
When, downstream from the units of the DOV707 and RDI705 ranges, there is a default current to earth which
supersedes the threshold corresponding to its value (30mA or 300mA, depending on version), the unit cuts off at very
high speed. The reclosure timer immediately enters into a countdown. When this concludes, the unit recloses. If the
number of reclosures is used up (depending on version) in a period of time inferior to that indicated on the reset to zero
counter (depending on version), the unit will block. cf. Technical characteristics.
By Por " default current deriving or leaking to earth” one should understand it as those currents which derive to earth
generating a difference of intensities between the active output conductors (phases and neutral).
If the leakage or derivation closes the circuit between phases and/or neutral of the live output conductors, there is no
difference in intensity between phase and neutral. In this case, the differential protections do not act but then neither would
any receiver being supplied from phase to neutral.
The functioning of the protection devices against defect currents which derive or leak to earth (differentials) is based on the
measurement of the difference in intensity between the live conductors (phase and neutral). Once the pre-established
threshold has been exceeded, the cut-off elements of the device come into play.
The differential is a standard element of protection. It measures defect currents to earth in order to cut off should this
leakage exceed certain pre-established values.
For safety reasons, the norm stipulates that a differential must cut off within 50% and 100% of its programmed I
n value.
As a norm, differential manufacturers establish this margin midway in this range, i.e. the threshold is established at 25%
below the original programmed I
n value. The Safeline units are tared in the same way.
Over recent years, there has been a steadily growing proliferation of electrical receiver equipment which relies on
electronics in order to increase its performance and cut down on energy. For example, tools and domestic appliances with
speed regulation, electronics in general, etc... which operate with rectified or pulsing currents.
The derivations or defect currents of these rectified or pulsing currents constitute a risk which has been taken into account.
Hence, the inclusion of protections against derivations from pulsing currents
The SURELINE differential protection differentiates itself from others because of its high precision, very high speed and its
constant self-verification, amongst other characteristics.
Protection against permanent and transient overvoltage
In the event of a permanent or transient overvoltage of a value superior to that programmed (cf. technical characteristics),
the unit engineers a very high-speed cut-off via the tripping coil and the motor-drive.
The unit withstands permanent overvoltages of 450 V RMS and transient (300ms) 1000V peak voltages. In the event of
peak voltages of over 1000 V, the unit protects itself by means of a built-in XXXmA T fuse. Prolonged use in higher-rank
voltages is not recommended. The unit will reset automatically when the anomalous condition desists. Whilst there exists
an overvoltage, the unit will not reset.
Summary of Contents for Sureline DOV707H
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