IEEE C62.39-2012 pdf download IEEE Standard for Test Methods and Preferred Values for Self-Restoring Current-Limiter Components Used in Telecommunication Surge Protection
6.1.2 Test method
The resistance shall be measured when the component is in thermal cquilibrium at the atmosphericconditions given in the product documentation. The default standard atmospheric conditions are given in5.1. Components mounted by reflow soldering shall be measured 1 h or more after soldering.
Resistance measurement shall be made without any appreciable self-heating of the component (IEC 60738-:2006 (B3], 7.5), using low-current resistance measuring equipment such as a digital meter.
The measuring method shall be such that the error does not exceed the following:
10% of the resistance tolerance
10% of the specified maximum difference resistance of paired OCPs
6.1.3 Values
OCPs used in telecommunication applications have a typical resistance range of 1 2 t 50 2. There are nopreferred resistance values given, as the values appropriate for a given application are dependent of thesignal performance requirements and the desired time-to-trip.
When the 0CPs are provided as pairs, one in each wire of a twisted pair, an important characteristic is theresistance difference between the OCPs. For PPTC thermistors, the biggest resistance difference occursafter a trip event.
6.1.4 Criteria
The measured resistance value and, if necessary, the differential resistance value of a pair, shall be withinthe limits given in the product documentation.
6.2 Hold current, n
6.2.1 Purpose
This test verifies that the OCP does not trip when conducting the minimum specified value of thecomponent hold current, . for a specified time at specified ambient conditions. Typically the lowest valueof hold current will occur at the highest temperaturc.
6.2.2 Test method
The OCPs shall be connected and enclosed in a chamber as in Figure 2. The chamber temperature isadjusted to the value given for this test in the product documentation and the air allowed to becomestationary.
The OCPs are connected to constant currentthevaluein the product documentation.Themaximum open-circuit voltage of a supply shall beower than 50% of maximum voltage ac,/max value orThe minimum open-circuit supply voltage shall be atthe voltage specified in the product documentation.least five times greater than the voltage developed across the OCPat a current of h. The voltage acrosseach OCP is measured and recorded at the time given in the productdocumentation. If no time is specified
IEEE C62.39-2012 pdf download
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