Rec. ITU-T K.77 (07/2019) - Characteristics of metal oxide varistors for the protection of telecommunication installations
Summary
History
FOREWORD
Table of Contents
Introduction
1 Scope
2 References
3 Definitions
     3.1 Terms defined elsewhere
     3.2 Terms defined in this Recommendation
4 Abbreviations and acronyms
5 Service conditions and storage conditions
     5.1 Service conditions
     5.2 Storage conditions
6 Electrical requirements
     6.1 Varistor voltage
     6.2 Maximum continuous operating voltage
     6.3 Leakage current
     6.4 Capacitance
     6.5 Maximum clamping voltage
     6.6 ESD impulse test
     6.7 Rated energy
     6.8 Impulse life characteristic
     6.9 Service life under voltage-temperature stress
     6.10 TOV- withstanding duration
     6.11 TOV-withstand characteristic
     6.12 Insulation resistance (for insulated MOV only)
     6.13 Voltage proof (for insulated MOV only)
     6.14 ESD clampling voltage
     6.15 Maximum impulse voltage
7 Test methods
     7.1 Varistor voltage
     7.2 Maximum continuous operating voltage
     7.3 Leakage current d.c.
     7.4 Capacitance
     7.5 Clamping voltage
     7.6 ESD impulse test (for surface mount electrostatic protective varistors only)
     7.7 Rated energy
     7.8 Impulse life characteristic
     7.9 Service life under voltage-temperature stress
     7.10 TOV-withstand duration
          7.10.1 Description
          7.10.2 Test set-up
          7.10.3 Test steps
     7.11 Insulation resistance (for insulated MOV only)
     7.12 Voltage proof (for insulated MOV only)
     7.13 ESD clamping voltage
     7.14 Maximum impulse voltage
8 Environment tests
     8.1 Robustness of terminations
          8.1.1 General
          8.1.2 Wire terminations robustness
          8.1.3 Strap terminations robustness
          8.1.4 Threaded studs or screw terminations robustness
          8.1.5 SMV terminations robustness
     8.2 Solderability
          8.2.1 Disc type solderability
          8.2.2 SMV solderability
     8.3 Resistance to soldering heat
          8.3.1 Disc type resistance to soldering heat
          8.3.2 SMD type resistance to soldering heat
     8.4 Vibration
     8.5 Shock
     8.6 Rapid changes of temperature
     8.7 Climatic sequence
     8.8 Damp heat, steady state
     8.9 Fire hazard
     8.10 Solvent resistance of marking
     8.11 Component solvent resistance
9 Identification
     9.1 Marking
     9.2 Documentation
10 Ordering information
Annex A  Impulses used in this Recommendation
     A.1 Definition of T1/T2 impulse
     A.2 Tolerances for T1/T2 impulse (Figures A.1 and A.2)
     A.3 Tolerances for rectangular impulse (Figure A.3)
     A.4 ESD discharge current impulse (Figure A.4)
Annex B  Test methods for impulse life characteristics of MOV
     B.1 Scope
     B.2 Method for impulse life characteristics
          B.2.1 Sampling and initial measurement
          B.2.2 Test currents
          B.2.3 Failure criterion
          B.2.4 Weibull distribution (Weibull distribution function):
     B.3 Expressions of MOV impulse life characteristics
          B.3.1 Basic impulse life equations
          B.3.2 Graphical expressions of the impulse life characteristics
Annex C  Test methods for service life under voltage-temperature stresses
     C.1 Scope
     C.2 Initial qualification approval test
          C.2.1 Sampling plans
          C.2.2 Test set-up
          C.2.3 Test hours
          C.2.4 Number of samples (N)
     C.3 Test procedures
          C.3.1 Sampling and initial measurement of the samples
          C.3.2 Installation of the samples in the test chamber
          C.3.3 Measurement during the test
          C.3.4 Restoration and measurement after 2000 hours
          C.3.5 Conformance criterion for qualification approval test
     C.4 Maintenance of qualified failure rate (FR) level
          C.4.1 Sampling plans for qualification maintenance test
          C.4.2 Requirements
     C.5 Failure distribution function of service life
Bibliography