Test & Measurement Lexikon - Triax

Test & Measurement Lexicon
Derating curve
According to the derating curve (load reduction curve according to
DIN EN 60512-5-2), the operating current at higher ambient temperature
is to be reduced. The current loading capacity of measurement
accessories is limited by the thermal load-bearing capacity of
the contact materials or insulating parts and through the valid upper
limit temperature of measurement accessories according to IEC
61010. Therefore the derating curve applies as a function of environmental
temperature to currents that may continuously pass
through each contact element of the plugs, without exceeding the
upper limit temperature.
Derang-Curve
Current in A
X
Temperature Curve
Derang-Curve * 0,8
Cross Temperature 70°C
0 10 20 30 40 50 60 70 80
IEC 61010
The international standard IEC 61010 “Safety specifications for electrical
measurement, control, regulation and laboratory devices” defines
the protection of the user against dangerous currents to the
human body and electrical burns. For measuring and testing accessories,
the section IEC 61010-1 and IEC 61010-031 will be applied.
The standards correspond to EN 61010-1 and EN 61010-031.
All products of Hirschmann Test & Measurement range are designed
according to this standard.
Insulation
As far as insulation is concerned, a distinction is made between basic
insulation and double or reinforced insulation. For hand-held measuring
accessories of safety system, the standard specifies double or
reinforced insulation. This consists of the basic insulation, which
ensures minimum protection against dangerous currents for the
human body, and an additional insulation, which guarantees protection
against dangerous currents for the human body when the
basic insulation fails. SKS uses double or reinforced insulation for all
products of the 2 mm & 4 mm safety system to protect the user.
Temperature in °C
Lexicon
The derating curve describes the relation between currents, thereby
caused increase of temperature (power loss on contact resistance)
and environmental temperature of the measurement accessory. A
linear coordinate system will be marked with current on the vertical
axis and environmental temperature on the horizontal axis, which
ends with the upper limit temperature of the measurement accessories.
The valid upper limit temperature for measurement accessories
is according to IEC 61010 as follows:
Measurement Category
• Non metallic materials: 70°C
In the Measurement Category, application fields are classified according
to the potential risk for the user, since transient voltage • Metallic materials: 55°C
surges
Double insulation
Double insulation consists of basic insulation and an additional insulation.
Gripping area
The gripping area is the area in which the user can touch a measuring
medium during operation without being exposed to dangerous
currents for the human body.
It is clearly marked and constructional separated from dangerous
area under voltage. If used properly the measuring media should
only be touched on the designated gripping areas. Wrongful use or
the use of damaged products will cause high, crucial safety risks.
High frequency (HF)
The electromagnetic frequency spectrum is divided into different sections
in technology. This classification indicates the area above the
acoustic waves between 30 kHz and 300 MHz as high frequency (HF)
and the frequency range between 300 MHz and 300 GHZ as electromagnetic
waves. The SKS products of the category "HF measuring
technique" can also partly be used for measurements in the area of
electromagnetic waves.
may lead to danger to the user. In general the following applies: The
higher the measurement category, the higher will be the safety requirements
that apply to the product.
Measurement Category I (CAT I)
Measurement Category I is for current circuits within devices that are
not connected to the mains, electronic devices, battery devices, etc.,
in which only minor transient overvoltage can occur.
Measurement Category II (CAT II)
Measurement Category II is for devices that are connected to the
mains or those that receive power via the mains, but are not a part
of the installation. In these devices, there may be transient overvoltage
due to switching processes (for example mains-powered entertainment
electronic appliances, domestic appliances).
Measurement Category III (CAT III)
Measurement Category III is for voltages in the field of distribution
installations and fixed installations (for example switches, socket outlets,
general domestic installations).
Measurement Category IV (CAT IV)
Measurement Category IV is for voltages at the source of the installation
(for example overhead lines, cable networks).
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