Switch-Rated Plugs and Receptacles

MELTRIC Switch-Rated plugs and receptacles are listed for “Branch Circuit Disconnect Switching” and “Motor Circuit Disconnect Switching.” Models are available with branch circuit switch ratings from 20 to 200A and with motor circuit switch ratings from .75 to 200 hp. Models up to 100A and 50 hp are also rated to withstand and close into a 100kA short circuit, when protected with RK1 fuses.

MELTRIC DS and DSN Series are performance tested and listed to UL 2682, which is the standard specifically for Switch-Rated Plugs and Receptacles. It includes more severe testing than the standards for ordinary pin and Sleeve or twist lock devices require. To obtain both the branch circuit and motor circuit switch ratings, the same device must pass the following sequence of electrical performance tests in order:

HP Locked Rotor Overload Test

50 operations @ rated voltage and amperage that is 600% of the motor FLA for the associated hp rating, with a power factor of 0.5 or less.

Temperature Rise Test

Performed @ rated current with a maximum rise of 30°C permitted

Electrical Endurance

6000 operations @ rated voltage and rated amperage, with a power factor of 0.8 or less

Other required performance tests including, resistance to arcing, voltage withstand @ 3000V, and short circuit make and withstand tests are performed on separate devices.

Silver-Nickel Contact Material Provides Superior Conductivity

MELTRIC uses solid silver-nickel contact surfaces on its Switch-Rated plugs and receptacles. The contacts’ 85% silver and 15% nickel composition combines the durability of nickel with the excellent conducting properties of silver.

Silver-nickel contacts provide significant advantages over the brass materials used on most other types of plugs and receptacles:

• Silver-nickel maintains low contact resistance and superior electrical properties even after oxidation and tarnishing.
• Silver-nickel withstands arcing very well and only welds at extremely high    pressure and temperature.
• The hardness of nickel gives the silver-nickel contacts excellent wear resistance.
• Silver-nickel performs well in and withstands wet and corrosive environments.

The combination of silver-nickel contacts with a spring-loaded butt-style design makes the contacts ideal for repetitive making and breaking of connections under load.

Limitations of Brass as a Contact Material

• Brass is not arc resistant, so it is not suitable for repeated making and breaking under load.  
• Brass is a soft material and  wears rapidly, degrading the operational characteristics of the contact.
• Brass oxidizes easily, preventing it from performing well in wet or corrosive environments.
• The contact resistance of brass increases rapidly due to tarnishing that occurs during normal use. 

MELTRIC uses a spring-loaded ejection system to provide a quick and secure separation of the contacts during disconnection of the circuit. The quick break mechanism drives the contacts open in 15 ms or less, minimizing internal arcing and its impact on the contacts.

MELTRIC Switch-Rated devices disconnect the circuit simply by pushing the OFF button.  This automatically breaks the connection and ejects the plug to the OFF position. The plug can then safely be removed by rotating it 30° counterclockwise and withdrawing it.

Spring-Assisted Terminals Provide Superior Conductor Connections

On traditional plugs and receptacles, the loosening of terminal screws is a common cause of failure.  MELTRIC devices have patented, spring-assisted terminals that provide more permanent and secure conductor connections.

As the terminal screw is tightened, pressure is generated against the conductor and causes the split-terminal body to expand and elliptically deform the spring ring around the terminal. Since the spring ring wants to return to its original circular shape, it exerts a constant pressure against the terminal conductor, pushing them together. This constant spring pressure on the screw and conductor helps to compensate for strand settlement and conductor yield, while providing superior resistance to the effects of vibration, shock, and thermal cycling.

Control, Monitor, Communicate

MELTRIC Switch-Rated plugs and receptacles are available with optional auxiliary/pilot contacts that allow users the convenience and  flexibility of controlling auxiliary equipment, monitoring process parameters, and/or communicating alarms without the need for secondary connectors. The larger models are available with up to 6 auxiliary contacts.

MELTRIC DS and DSN Switch-Rated plugs and receptacles achieve their rated watertightness simply by connecting the plug and receptacle. There is no need to thread on or turn watertightness rings as is required on many pin and sleeve devices. DSN Series devices provide Type 4X and IP69K/IP69 watertightness, while the DS Series provides Type 3R as standard or Type 4X as an option.