Mark VI Circuit-Switcher

• Higher-than-ever 31.5-kA fault-interrupting rating and 3-cycle interrupting time.
• Three-phase tripping by electrically linked interrupters — provides tripping simultaneity of less than ¼ cycle.
• Hermetically sealed interrupters — eliminates the hassle of field-filling with SF6 gas. Interrupters provide full dielectric ratings when open.
• Reliable performance — Mark VI uses the same robust high-speed disconnect as Mark V Circuit-Switcher and the heavy-duty Mark VI CS-1A Switch Operator.

Optional features include:

• Pre-insertion Inductors. With the addition of pre-insertion inductors, Mark VI Circuit-Switcher is ideal for capacitor-bank applications, combining switching, protection, and transient overvoltage control in one device. Pre-insertion inductors limit inrush current and overvoltage at the capacitor-bank bus, limit phase-to-phase switching-surge overvoltages at remote transformers, and control overvoltages on long, open-ended lines and on the user’s utilization-voltage bus.
• S&C Mounting Pedestals. Dramatically reduce installation time with S&C’s easy-to-install mounting pedestals.

Voltage and Continuous, 4-Hour, Peak Withstand, and Fault-Closing Current Ratings — 50/60-Hz.

Interrupter Current Ratings For Shunt Capacitor Bank Switching and Protection

Interrupter Current Ratings For Transformer Switching and Protection

Pre-insertion inductors are especially suited for limiting transient overvoltages which, through voltage manification, can result in nuisance tripping of adjustable-speed drives and other sensitive electronic devices. Voltage magnification can occur where power-factor correction capacitors and/or voltage control capacitors are applied on the utility distribution system or on a utility customer’s low voltage bus, and is caused by a near-resonant condition between the switched capacitor bus and the capacitances at lower voltages.

Pre-insertion inductors are more effective than controlled-closing schemes and pre-insertion resistors for limitation of:

• Inrush current and overvoltage at the capacitor bank bus — curbing induced transients in substation low-voltage circuits that can cause spurious signals, insulation puncture, and component damage.
• Switching-surge overvoltages at remote transformers — which can lead to decreased transformer life, or even failure.
• Overvoltages on long open-ended lines. Such overvoltages can cause nuisance arrestor operation.
• Transient overvoltages on users’ utilization-voltage bus — voltage magnification of capacitor-switching transients can cause nuisance tripping of adjustable-speed drives and other sensitive electronic devices.

How does the pre-insertion inductor work?

First, an open-air arc makes up the initial circuit through the pre-insertion inductor. The inductor core picks up the inrush current before it reaches the main contact. Then, the pre-insertion inductor is bypassed, and disconnected as the moving arcing rod rotates. As the main contact is made, the pre-insertion inductor is completely removed from the circuit.

The sliding contact arrangement places the pre-insertion inductor in the circuit for only a few cycles. That’s how long it takes to provide high-quality transient control.

For complete application information on S&C Pre-insertion Inductors refer to S&C Data Bulletin 711-95 or contact the nearest S&C Sales Office.

The Mark VI CS-1A Switch Operator direct-drives the vertical-break disconnect of the Mark VI Circuit-Switcher. It provides trip-free capability. Should the Mark VI be inadvertently closed into a fault sensed by user-furnished relays, Mark VI will trip immediately.

The operator features a sturdy welded enclosure with baffled louvers that allow air circulation, but keep out rain. The interior of the weatherproof, dustproof enclosure is accessed by a hinged door . . . rather than removal of the entire enclosure.

The Mark VI CS-1A Switch Operator includes:

• Six adjustable auxiliary switch contacts, coupled to the motor
• External trip and close push buttons with padlockable cover
• Built-in manual operating handle for the disconnect
• Decoupling mechanism that allows decoupling and locking of the disconnect in the open position
• Mechanical position indicator
• Non-resettable operation counter.

Optional features for the Mark VI CS-1A Switch Operator include:

• Additional auxiliary-switch contacts
• LED position indicating lamps
• Remote-control blocking switch
• Space-heater thermostat
• Duplex receptacle with ground-fault circuit interrupter, and convenience light lampholder with switch.

A Resource for Selecting a Substation Transformer Protective Device

One criterion in selecting a distribution substation transformer protective device is its ability to protect the transformer from secondary-side limited faults . . . or “through-faults.” These faults are difficult to detect by the overcurrent relay of the line-terminal circuit breaker, because the magnitude of the fault current is relatively low — being limited by the impedance of the transformer. These faults are a challenge to clear as well, because of their high transient recovery voltage.

Click here to use the Through-Fault Current Calculator.