Reference standards:
EN60051, EN50081, EN50082, EN61010, IEC60051, IEC61010, DIN43780

Temperature limites:
The measuring instruments and their accessories withstand temperature variations from -25 centigrade to +40 centigrade( 55 centigrade in the tropical weather proof version) without permanent fault.

Relative humidity:
The accuracy class is maintained within the interval of 25% to 80% of non condensed relative humidity.

Auxiliary power supply:
The accepted tolerance for nominal values of the auxiliary power supply is:
Voltage: +10%~-15% Frequency: 45-65Hz