Electrical Systems & Mechanical Components Flashcards
7 cards from real CST practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Electrical Systems & Mechanical Components flashcards as text
Which electrical phenomenon causes a load cell output to drift upward shortly after a heavy load is applied, even though the actual load has not changed?
Answer: Thermal zero drift from heat generated in bridge resistors
Self-heating of the Wheatstone bridge resistors from excitation current can cause the zero or span to drift until the load cell reaches thermal equilibrium.
A rocker pin assembly on a mechanical scale platform primarily serves to:
Answer: Transfer vertical load to the load cell while allowing thermal expansion
Rocker pins transfer the weighing force vertically to the load cell while allowing the platform to expand and contract thermally without inducing side loads.
What does a non-linearity error in a load cell indicate?
Answer: The output deviates from a straight line between zero and rated capacity
Non-linearity is the maximum deviation of the load cell's output curve from a best-fit straight line expressed as a percentage of rated output.
A surge protector is installed on a scale indicator's AC input primarily to protect against:
Answer: Voltage transients caused by lightning or switching inductive loads
Surge protectors clamp high-voltage transients caused by lightning strikes or inductive switching events before they can damage sensitive indicator electronics.
When a technician performs a linearity test on a scale, they apply test loads at:
Answer: Multiple points spanning the capacity in both ascending and descending order
A complete linearity test applies loads at multiple points in both ascending and descending directions to capture both non-linearity and hysteresis errors.
The IP (Ingress Protection) rating IP69K on a load cell specifically indicates protection against:
Answer: High-pressure, high-temperature steam cleaning jets
IP69K certifies protection against high-pressure (80–100 bar) and high-temperature (80°C) water jets used in washdown and sanitation processes.
Which condition will cause a negative (below-zero) reading on a properly functioning digital scale indicator?
Answer: A tare weight is stored and the platform is then unloaded below the tare reference
When a tare is stored and weight is then removed below the tare reference point, the net weight calculation produces a negative display reading.