Overload Relays
From general applications to special applications, Siemens offers a wide range of overload relays that provide superior motor protection. Overload relays are used to protect motors from excessive heat resulting from sustained motor overloads, rapid motor cycling, stalled rotor conditions and phase loss.
Solid-State Overload Relays, Class 48, 958, & 958L
Solid-state overload relays are ambient insensitive, self-powered and do not require heater elements.
Class 48 ESP100 solid-state overload relays offer additional protection over standard thermal overload relays. In addition to overload protection, they trip in three seconds or less in the event of a phase loss – fast enough to prevent motor damage. The ESP100 is available with trip class 10, 20, and 30 to fit a wide variety of applications.
Class 958L ESP100 special use solid state overload relay are designed specifically for the oil market and the cyclical loads experienced with these types of pumping applications. These overload relays provide protection on all standard motors, oil well pump motors, multi-torque connections, and ultra-high slip motors.
Thermal Overload Relays, Class 48
Ambient compensated bimetal overload relays are designed to compensate for the ambient air temperature surrounding the overload. This helps to prevent the occurrences of nuisance tripping. Additionally, they are automatic or manual reset selectable. Heater elements are required.
Current Sensitive Relays, Class 97
Current sensitive relays monitor motor current and provide an instantaneous output if the motor current is over or under an adjustable set point. These over or under current conditions may be the result of a change in system status such as a jam, broken belt or dry well. Start-up delay, trip delay and current trip adjustments are provided to match the current sensitive relay to a specific application.