BS ISO 19235:2015 pdf download – Analogue quartz clocks — Timing accuracy
1 Scope This International Standard specifies the basic parameters, requirements, and testing methods of timing accuracy for analogue quartz clocks, hereinafter referred to as “the quartz clock”. This International Standard applies to analogue quartz table and wall clocks which the oscillator frequency is 32 768 Hz and the nominal voltage is DC 1,5 V. Analogue quartz clock movements can refer to it. This International Standard does not apply to the following quartz clocks: — clocks for particular applications such as clocks used in aircraft, ship, vehicle, and facilities; — clocks incorporated into other products; — clocks in which time is radio-synchronized. 2? Terms? and? definitions For the purposes of this document, the following terms and definitions apply. 2.1 mean instantaneous rate m arithmetic mean value of three instantaneous rates of the quartz clock separately measured on three successive days, in “s/d” or “s/m” 2.2 voltage? coefficient C U variation rate of instantaneous rate of the quartz clock caused by the variation of source voltage 2.3 temperature? coefficient C t variation rate of instantaneous rate of the quartz clock caused by the variation of temperature 2.4 nominal voltage U n voltage for which the movement is destined 3 Basic parameters and requirements of timing accuracy 3.1 Mean instantaneous rate, m After the quartz clock has been continuously running for 3 d, the mean instantaneous rate shall be within −1,0 s/d to +1,0 s/d. 3.2? Voltage? coefficient, C U The voltage coefficient, C U , shall be within −1,0 s/(d·V) to +1,0 s/(d·V).
3.3? Temperature? coefficient, C t The temperature coefficient, C t1 , shall be within 0 s/(d·°C) to +0,1 s/(d·°C) and C t2 shall be within −0,1 s/(d·°C) to 0 s/(d·°C). 4 Test methods 4.1 Test conditions 4.1.1 Test environment The test ambient temperature shall be 18 °C to 25 °C, the temperature variation shall be within ±2 °C during the whole test and the relative humidity shall be between 50 % and 70 %. 4.1.2 Power supply Unless otherwise specified, the test power supply during the test shall be the nominal voltage of the quartz clock of DC 1,5 V. 4.1.3 Pre-running Before the test, the quartz clock shall run for at least 2 h in the test environment specified in 4.1.1. 4.2 Test apparatus The resolution and maximum permissible error of the test apparatus can refer to Table 1.