NEMA Overload & Current Sensitive Relays

From industrial to construction applications, Siemens offers a wide range of overload relays. Our NEMA class of overload relays are used to protect motors from the cold, such as refrigeration, where the ESP200 uses its auto reset mode to help you avoid shutdowns. To protect motors against over-heating, the ESP200 also has phase unbalance protection and thermal memory to prevent the motor from restarting while too hot.

When extreme is a standard for you (hot or cold), we get the job done.

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Solid State Overloads

3UB8 ESP200 solid-state overload relays

ESP200 overload relays provide accuracy unmatched in the market. With repeat accuracy of greater that 99%, trips can be set to the most specific conditions, resulting in both longer motor life and cost savings. The ESP200 solid state overload relay is so simple to configure. Just set the FLA dial to match the FLA of the motor nameplate and set the DIP switches per the faceplate engraving. No software or manuals are required.

Key Features:

Trip Classes - 5, 10, 20, or 30 Selectable by DIP-switches
Phase Loss Protection - Trips in less than 3 Seconds
Phase Unbalance - Trips based on Trip Class selected
Ground Fault - Trips 60% of Motor Current
FLA dial with wide Adjustment - 4:1 ratio

Special Use Solid State Overloads

958 ESP200 solid-state overload relays

The 958 is designed to provide excellent protection of hermetically sealed and artificially cooled motors that require ambient insensitive and quick trip response times. Combined with a series lockout relay, it provides unsurpassed protection for hermetically sealed compressor motors in air conditioning applications. The combination of high trip speed, current adjustment, and ease of installation makes it perfect for these applications. The trip curves are customized to provide proper overload protection for these loads without causing nuisance tripping.

It has selectable manual or automatic reset mode, and provides ground fault selection to protect equipment from damage in case of a fault.

Oil Field Solid State Overloads

958L ESP200 solid-state overload relays

The 958L is designed for the cycling loads of pumping applications in the oil market. They provide protection for standard motors, oil well pump motors, multi-torque connections, and ultra-high slip motors.

Rotors can be damaged in less than 15 seconds during motor stall conditions if electrical power is not removed. To prevent damage during motor stall, the 958L solid state overload removes the power in 7 seconds at 250% lock rotor current. Therefore, the motor casing and the rotor will be protected from damage saving users money and time.