Due to effects of time: The prominent aspects of test instrument for instance input dividers, voltage references, current shunts etc are vulnerable to outcomes of time and register minor shifts over time. This shifting spells no difficulties if calibration services are widely used according to fixed routine. However a good inadvertent hard dropping of current clamp, for instance, can hit the equipment "out of cal" resulting in gross calibration errors. An accidental exposure of DMM (Digital Multimeter) to present overload can render it inaccurate. Some users think that these impacts won't affect the inputs owing to their breaker-protected nature. However, such protective devices could possibly fail to trip in response to abrupt, momentary changes in voltage or current. A massive voltage input can leap over the protective device completely. Test equipment calibration will set right this sort of errors and as well bring back the sanctity of measurements.
For top quality guarantee: Calibration fine-tunes the test equipment and guarantees secure plus reliable use to acquire correct examination outcomes through extremely sensitive products. This is a quality assurance exercise.