Operating instructions for POLIM
©
-D surge arrester ABB
6 EN Doc. 1HC0010173 AB
3. DESCRIPTION
3.1. Intended use
The POLIM
®
-D is a surge arrester intended for use in high- and medium-voltage
applications. Surge arresters protect the insulation of high voltage and medium
voltage devices against unacceptable overvoltages which are caused by lightning
or switching operations.
The manufacturer is not liable for resulting damages from further, unintended use.
The operator accepts all responsibility for using the POLIM
®
-D outside of its in-
tended application range as specified in this document.
3.2. Structure and function
The POLIM
®
-D surge arrester is constructed from serially connected, non-linear
metal-oxide (MO) resistors. These MO resistors have an extremely non-linear re-
sistance property. At the maximum operating voltage of U
c
, only a small capacitive
current will flow in the mA range. With an increase in voltage, the MO resistors en-
ter a highly-conductive state practically without delay. Thus any further increase in
voltage is limited to the specified residual voltage values. After the decline of the
overvoltage the arrester immediately turns back to the non- or slightly-conductive
state. The MO arrester converts the energy of the surge into heat, which it trans-
fers to the surrounding air.
The stack of MO resistors and connection equipment is held together with loops
made of fiberglass-reinforced plastic. The directly molded silicone housing protects
it from all environmental and weather influences. This design has proven to be the
best solution in every environment for years.
The POLIM
®
-D surge arrester is optionally equipped with a disconnecting device
(disconnector). This device disconnects the POLIM
®
-D surge arrester from the
power network, when it has been overloaded and destroyed. Disconnecting is
done by firing of a small propellant charge in the disconnecting device.
The POLIM
®
-D is especially suited for overvoltage protection of:
• transformers
• cables
• other medium-voltage apparatuses and systems
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