Electrical Safety Devices for Motor Control Centre

There are many electrical safety device for motor control centre MCC:

1-Type of load

    The type of load that a MCC controls affects the choice of electrical safety devices. For example, some loads are resistive, such as heaters and lighting, while others are inductive, such as motors and transformers. Inductive loads require more current to start than to run, and they can generate back electromotive force (EMF) when switched off. Therefore, inductive loads need safety devices that can handle higher inrush currents and suppress voltage spikes. Some common electrical safety devices for inductive loads are magnetic circuit breakers, overload relays, and surge suppressors.

   2-Voltage level

The voltage level of a MCC determines the insulation and clearance requirements of the electrical safety devices. For example, low-voltage MCCs (below 600 V) can use air circuit breakers or molded case circuit breakers, which have smaller dimensions and lower costs than medium-voltage MCCs (above 600 V). Medium-voltage MCCs require vacuum circuit breakers or gas-insulated circuit breakers, which have higher insulation and arc-extinguishing capabilities. Additionally, medium-voltage MCCs need more protection devices, such as potential transformers, current transformers, and relays, to monitor and isolate faults.

   3-Coordination scheme

The coordination scheme of a MCC defines how the electrical safety devices operate in the event of a fault. For example, some MCCs use selective coordination, which means that only the device closest to the fault trips, while the rest of the system remains energized. This minimizes the impact of the fault on the production and reduces the downtime. Other MCCs use non-selective coordination, which means that multiple devices trip simultaneously, regardless of their location to the fault. This maximizes the safety of the personnel and the equipment, but it also increases the outage duration. The choice of coordination scheme depends on the criticality of the load, the availability of backup power, and the cost-benefit analysis.

     4-Installation location

The installation location of a MCC influences the environmental and physical factors that affect the electrical safety devices. For example, some MCCs are installed indoors, where they are protected from moisture, dust, and temperature fluctuations. Other MCCs are installed outdoors, where they are exposed to harsh weather conditions and vandalism. Therefore, outdoor MCCs need more robust and durable safety devices, such as metal-enclosed circuit breakers, weatherproof enclosures, and padlocks. Additionally, the installation location determines the accessibility and maintenance requirements of the electrical.

Components such as pT's , CT's, fuses , different protection motors in Mcc, , good configuration of unit trip in incomer of circuit breaker , good capacitor bank.