Motor protection envelope — 90 A, adjustable 70–90 A, Class 10
The Siemens 3RU5146-4LB0 is a SIRIUS thermal overload relay rated 90 A operational current, with an adjustable current response range of 70–90 A. This relay is designed for Size S3 contactor combination, mounting directly onto the contactor without occupying DIN rail space.
Panel fit and environmental tolerance
Dimensions are 140 mm depth, 70 mm width, 120 mm height — the width is the critical panel-spacing dimension. Siemens requires 6 mm clearance to grounded parts on the side. The relay operates from -20 to +70 °C and 0–100% relative humidity, and withstands 8g shock for 10 ms per IEC 60068-2-27, so it holds up in high-vibration MCCs. Mounting position is flexible: vertical surface with ±135° rotation or ±45° tilt front/back. Installation altitude is limited to 2000 m above sea level without derating.
Sourcing and lifecycle — active production, quoted to order
The relay carries a rated operational voltage of 1000 V at 50–60 Hz, surge voltage resistance 8 kV, and insulation voltage 1000 V with pollution degree 3. Typical power loss is 16.5 W total, rising to 21 W in hot operating state at rated current.