The following classes have been defined by the VdS to classify the security of burglary alarm control centres:
VdS today: Trust through security (VdS Schadenverhütung GmbH), formerly: Verband deutscher Sacherversicherer
VdS Alarm systems Class A (low security against sabotage)
Simple protection against attempts to penetrate in the sharp and blurred states; the switches have medium response sensitivity.
Simple contact elements are used.
VdS Alarm systems Class B (medium security against sabotage)
Medium protection against attempts to penetrate in the sharp and blurred states; the switches have medium response sensitivity.
A contact element plus additional conductor loop is used.
As soon as a line is cut, an alarm is generated.
VdS Alarm systems Class C (high security against sabotage)
Increased protection against attempts to penetrate in the sharp and blurred states; the switches have increased response sensitivity.
A contact element is additionally monitored by an additional external field contact.
Being manipulated with a magnet opens the line and creates an alarm.
Depending on the object to be protected, the VdS classes are usually combined with safety classes by the alarm system manufacturer.
Electrotechnical explanation of the variants
For alarm systems with magnetic switches, the following applies in principle:
A magnetic switch connected to an alarm system must be closed (!) And current must flow (!).
Normally closed contacts are open at rest, the magnet is not applied.
When the magnet approaches, the contact closes = "normally open".
Most Schüco magnetic switches are normally open contacts.
NC contacts are closed in idle state, the magnet is not applied.
When the magnet approaches, the = "NC contact" opens.
This form exists with magnetic switches only in combination with changeover contact.
Changeover contacts work depending on the connection.
There is either the function of a closer or an opener.
With VdS safety switches, all cable cores have the same sheath colour.
VdS guidelines require that all cores have the same colour for magnetic contacts.
For potential burglars, manipulation is made more difficult this way.
