A motor protection relay safeguards electric motors by detecting thermal stress, phase imbalance, stall, and abnormal ...

Single-phase and 3-phase AC squirrel cage induction motors need some type of control circuit to initiate a start or stop function. The two types of ladder control circuits commonly used are the 2-wire ...

Safety is a major concern in a good many motor-driven applications. This is true in industrial applications where motion starts when power is applied and especially true when power is restored after ...

In Part 1 of this two-part series, we presented a 3-phase, 480VAC motor circuit with its associated controls (Figure). We stepped through a logical, systematic approach to troubleshoot the main power ...

The proper selection of 3-phase solid state relays for motor control application depends not only upon a comprehensive understanding of 3-phase SSRs, but also of the 3-phase power system and typical ...

As an electric motor’s rotor turns in close proximity to the motor windings, a bucking voltage or back electromotive force (EMF) is generated. The back EMF (BEMF) generated across the start winding is ...

Relays and contactors use a variety of technologies to switch signals and power connections. Many devices called relays use similar techniques and topologies, but the terminology can be confusing.

Higher Capabilities for Safety-Rated Control Circuits A truly reliable safety control system must work even when some parts fail. Force-guided relays are unseen components that add another level of ...

Controlling a small dc motor without speed control sounds like a trivial task; a switch or a relay should suffice. However, several problems accompany this approach. For one, the switch, because of ...

Schweitzer Engineering Laboratories, Inc. (SEL) has introduced new features in the SEL-701 motor protection relay. These features include Acselerator QuickSet SEL-5030 software support and a ...

Per 2014 NEC Article 100, short circuit current rating (SCCR) is defined as: “The prospective symmetrical fault current at a nominal voltage to which an apparatus or system is able to be connected ...