US&S relay sizes?

US&S relay sizes?

• A. 150-250
• B. 100-200
• C. 200-300
• D. 50-100

Answer: (A)

Relays have different frame sizes that tell you how much switching power they can handle and how many contacts they provide. In US&S equipment, the mid-range frame is the one most commonly used for standard interlocking circuits. That size offers enough magnetic force to pull in the armature reliably and enough contact capacity for typical signaling tasks, without being oversized for the panel space or overheated by normal operation. That’s why the 150-250 range is the best fit here: it represents the usual mid-range size used in everyday interlocking relays. The smaller ranges tend to be for lighter-duty relays with fewer contacts, while the larger ranges are for heavier-duty duty cycles that aren’t needed in standard SMT-1 practice. So the 150-250 range aligns with the typical, widely used US&S relay size for these applications.

Relays have different frame sizes that tell you how much switching power they can handle and how many contacts they provide. In US&S equipment, the mid-range frame is the one most commonly used for standard interlocking circuits. That size offers enough magnetic force to pull in the armature reliably and enough contact capacity for typical signaling tasks, without being oversized for the panel space or overheated by normal operation.

That’s why the 150-250 range is the best fit here: it represents the usual mid-range size used in everyday interlocking relays. The smaller ranges tend to be for lighter-duty relays with fewer contacts, while the larger ranges are for heavier-duty duty cycles that aren’t needed in standard SMT-1 practice. So the 150-250 range aligns with the typical, widely used US&S relay size for these applications.