IEC 61010-2-30:2010 pdf – Safety requirements for electrical equipment for measurement, control, andlaboratory use- Part 2-030: Particular requirements for testing and measuring circuits.
b) An electrical quantity that is within specification for any TERMINAL shall not cause a HAZARD when it is applied to that TERMINAL or any other compatible TERMINAL, with the range and function settings set in any possible manner (see 101.3).
C) Any interconnection between the equipment and other devices or accessories shall not cause a HAZARD even if the documentation or markings prohibit the interconnection while the equipment is used for measurement purposes (see 6.6).
d) For measuring circuits that include one or more FUNCTIONAL EARTH TERMINALS, a RISK assessment (see Clauses 16 and 17) shall address the HAZARDS that may result lithe equipment is operated with a disconnected PROTECTIVE CONDUCTOR TERMINAL and If the operator unintentionally connects a FUNCTIONAL EARTH TERMINAL to any RATED voltage lot any other TERMINAL.
NOTE Oscilloscopes and spectrum analyzers are examples of equipment that often Include FUNCTIONAL EARTH TERMINALS in the measuring circuit. In many cases, the OPERATOR *111 esconnect IllS PROTECTIVE CONDUCTOR TERMINAL 50 that the FUNCTIONAL EARTH TERMINAL CSfl I loaf above earTh potential. ThIs allows me OPERATOR to make a floating measurement. buT introduces a HAZARO. If the OPERATOR should inadvertently conned Ille FUNCTIONAL EARTH TERMINAL to a HAZARDOUS LIVE voltage, then the chasSis 01 tIle measunag equipment may also be connected to the HAZARDOUS LIVE voltage, and the OPERATOR or a bystander could receive an elsetric shock from the chassis
e) Other HAZARDS that could result from REASONABLY FORESEEABLE MISUSE shall be addressed by RISK assessment (see Clauses 16 and 17).
Conformity Is checked as specified ,n 101.2, 101.3. 6.6. Clause 16 and Clause 17 as applicable.
101.2 Current measuring circuits
Current measuring circuits shall be so designed that, when range changing takes place.
there shall be no interruption which could cause a HAZARD.
Conformity Is checked by inspection, and. in case of døubt, by causing the device to switch the maximum RATED current 6 000 times.
Current measuring circuits Intended for connection to current transformers without Internal protection shall be adequately protected to prevent a HAZARD arising from interruption of these circuits during operation.
Conformity is checked by inspection, by overload tests at a value 0(10 times the maximum
RATED current for 1 s, and by causing the device to switch the maximum RATED current
6 000 times, No interruption which could cause a HAZARD shall occur during the tests.
101.3 Protection against mismatches of Inputs and ranges
101.3.1 General
In NORMAL CONDITION and in cases of REASONABLY FORESEEABLE MISUSE, no HAZARD shall arise when the maximum RATED voltage or Current of a measuring TERMINAL S applied to any other compatible TERMINAL, with any combination of function and range settings.
NOTE I MIsmatches 01 Inputs and ranges are asamptes of REASONABLY FORESEEASLE MISUSE, even It the documentation or markings ptohlbii &udh mismatch, A typical example is inadvertent connection of a high voltage to a measuring inpul intended fOr Current or resistance. Possible HAZARDS include .I.ctric shock, burns, tire, arcing and explosion
NOTE 2 TERMINALS that are clearly not of similar types and that will not retaIn the TERMINALS of the probe or accessory need not be tested
The equipment shall provide protection against these HAZARDS. One of these techniques shall be used.
a) Use of a certified overcurrent protection device to interrupt short-circuit currents before a HAZARD arises. In this case, the requirements of 101 .3.2 apply.
b) Use an uncertified current limitation device, an impedance, or a combination of both to prevent the HAZARD from arising. In this case, the requirements 01101.3.3 apply.
Conformity is checked by inspection, evaluation ol the design of the equipment, and as specified in 101.3.2 and 101.3.3. as applicable.
101 .3.2 Protection by a certified overcurrent protection device
An overcurrent protection device is considered suitable If It is certified by an independent laboratory to meet all of the following requirements.
a) The ac. and d.c. RATED voltages of the overcurrent protection device shall be at least as high as. respectively, the highest ac. and d.c. RATED voltages of any measuring TERMINAl, on the equipment.