Solutions for Automatic Source-Transfer
Hospitals, pumping stations, shopping malls, auditoriums, and many other commercial, institutional, and industrial power users require a high degree of service continuity for their critical loads. System reliability studies have shown that the power sources serving these facilities constitute the major cause of service interruptions, as a result of their extensive exposure to lightning, wind, and ice, as well as dig-ins and equipment failure.
Before considering more broadly based—and costly—solutions for improving grid reliability, power users having critical loads frequently implement primary-selective service for their facilities to ensure the continuity of power.
Primary-selective service can be provided economically using two radial utility source feeders. This simple, direct means for powering the loads facilitates quick location and isolation of a faulted feeder. One of the utility source feeders—designated the “preferred source”—normally serves the loads. If this source is lost, the other source feeder—designated the “alternate” source—is utilized to serve the loads. A power-operated interrupter switch is furnished for each source, along with a source-transfer control, to effect automatic two-way transfer.
S&C offers the industry’s most complete range of medium and high-voltage automatic source-transfer solutions.
For overhead distribution systems through 69 kV, S&C can furnish power-operated Alduti-Rupter® Switches, Scada-Mate® Switches, and Scada-Mate CX™ Switches, in combination with a Micro-AT® Source-Transfer Control or 6800 Series Automatic Switch Control. IntelliRupter® PulseCloser® Fault Interrupters can be utilized, too.
For underground distribution systems through 38 kV, S&C can furnish Source-Transfer Pad-Mounted Gear, Source-Transfer Vista® Underground Distribution Switchgear, System VI™ Switchgear, and Custom Metal-Enclosed Switchgear. Pad-Mounted Style IntelliRupter® PulseCloser® Fault Interrupters can be used as well.
Automatic Source-Transfer Pad-Mounted Gear Serving a Hospital
Here’s an example of automatic source transfer utilizing a unit of S&C Source-Transfer Pad-Mounted Gear.
Upon loss of the preferred utility source, the critical electrical loads of the hospital are transferred to the alternate utility source.
Upon subsequent return of the preferred source, the critical loads are transferred back to the preferred source. The reverse transfer is “open transition” to avoid paralleling the sources. If paralleling of the sources is permissible, “closed transition” reverse transfer may be selected
Optional Overcurrent Lockout Feature
S&C’s source-transfer solutions can be furnished with an overcurrent lockout feature. This feature prevents an automatic transfer operation that would close a switch into a fault.
If the overcurrent is due to a fault that is cleared by a source-side protective device, the prolonged loss of voltage will cause the associated source-transfer switch to open.
Automatic Source-Transfer Solutions for Overhead Systems
Let S&C help you select the solution right for your application, based on system voltage, continuous and interrupting current requirements of the loads, maximum-permissible source switching time, and requirement for additional automation.
Integer Style Alduti-Rupter Switches, available through 46 kV and up to 1200 A continuous and load interrupting.
Using AS-1A or AS-10 Switch Operators and a Micro-AT® Source-Transfer Control in Weatherproof Enclosure, transfer is achieved with two rotating-mechanism switches in 1.5 seconds maximum, or two reciprocating-mechanism switches in 2.4 seconds maximum.
With two Double-Break Style Alduti-Rupter Switches rated 69 kV, 1200 A continuous, and 600 A load interrupting—plus LS-2 Switch Operators and Micro-AT Control—transfer is achieved in 4.4 seconds maximum.
Split-bus application is possible.
Switch Operators
6801M Automatic Switch Operators provide 1.0 second maximum transfer time. Include mechanical, SCADA, and communication components in one enclosure. Can be integrated into an IntelliTeam® SG Automatic Restoration System.
Scada-Mate Switches, available through 34.5 kV, up to 900 A continuous, and 630 A load interrupting.
Using a 6802 Automatic Switch Control, transfer is achieved with two Scada-Mate Switches in 2 to 3 seconds. Split-bus application is possible with one 6802 Control and one 6801 Control.
Scada-Mate Switches include sensors for three-phase monitoring of line current and single- or three-phase monitoring of voltage. 6801 and 6802 Controls can be integrated into an IntelliTeam SG Automatic Restoration System.
Scada-Mate CX Switches, available through 25 kV and 900 A continuous and load interrupting.
Using a 6802 Automatic Switch Control, transfer is achieved with two Scada-Mate Switches in 2 to 3 seconds. Split-bus application is possible with one 6802 Control and one 6801 Control.
Scada-Mate CX Switches are optionally available with sensors for three-phase monitoring of line current and voltage. 6801 and 6802 Controls can be integrated into an IntelliTeam SG Automatic Restoration System.
IntelliRupter® PulseCloser® Fault Interrupters
IntelliRupter PulseCloser Fault Interrupters, available through 38 kV, up to 800 A continuous, and up to 16 kA interrupting.
When furnished with the IntelliTeam® SG Automatic Restoration System and SpeedNet™ Radios, or fiber-optic modems, transfer is achieved with two IntelliRupters in 1.5 to 1.8 seconds. Using the loop restoration feature, transfer is achieved with two IntelliRupters in 0.6 to 0.8 second.
Not limited to two-way transfer. IntelliRupters include sensors for three-phase monitoring of line current and three-phase monitoring of voltage on both sides of the switch Communicating IntelliRupters can be integrated into an IntelliTeam SG Automatic Restoration System.
Summary of Solutions for Overhead Systems
| Switching Devices | Voltage, kV | Continuous Current, Amperes | Interrupting Current, Amperes | Type of Switch Operator | Type of Control | Common-Bus Maximum Source-Transfer Time | Suitable for Split-Bus Application? | Suitable for IntelliTeam SG Integration? |
|---|---|---|---|---|---|---|---|---|
| Two Integer Alduti-Rupter Switches | Up to 46 | Up to 1200 | Up to 1200 | AS-1A | Micro-AT Control | 1.5 sec | Yes | No |
| AS-10 | 2.4 sec | Yes | No | |||||
| 6801M Automatic Switch Operator | 1.0 sec | Yes | Yes | |||||
| Two Double-Break Alduti-Rupter Switches | 69 | 1200 | 600 | LS-2 | Micro-AT Control | 4.4 sec | Yes | No |
| Two Scada-Mate Switches | Up to 34.5 | Up to 900 | 630 | Integral | 6802 Control | 2 to 3 sec | Yes, with one 6802 Control and one 6801 Control | Yes |
| Two Scada-Mate CX Switches | Up to 25 | 900 | 900 | Integral | 6802 Control | 2 to 3 sec | Yes, with one 6802 Control and one 6801 Control | Yes |
| Two IntelliRupter PulseCloser Fault Interrupters | Up to 38 | Up to 800 | Up to 16000 | Integral | Integral | 1.8 seconds using IntelliTeam SG and approved communication devices. 0.8 second using loop restoration | Yes | Yes |
Automatic Source-Transfer Solutions for Underground Systems
Let S&C help you select the solution right for your application based on system voltage, continuous and interrupting load-current requirements, maximum-permissible source switching time, and additional automation requirements.
Source-Transfer Pad-Mounted Gear
Source-Transfer Pad-Mounted Gear is available through 27 kV, 600 A continuous and load dropping, and up to 14 kA RMS symmetrical short-circuit. The gear includes Mini-Rupter® Switches with stored-energy switch operators plus a Micro-AT® Source- Transfer Control or a 6802 Automatic Switch Control.
Transfer is achieved in about ½-second with a Micro-AT control or in 3 seconds with a 6802 control. Common bus only. A 6802 control can be integrated into an IntelliTeam® SG Automatic Restoration System. Serves one or two critical loads.
Source-Transfer Vista® Underground Distribution Switchgear
Source-transfer Vista Underground Distribution Switchgear is available through 38 kV, 630 A continuous and load dropping, and up to 25 kA RMS symmetrical short-circuit. The gear includes motor-operated load-interrupter switches plus a Micro-AT® Source-Transfer Control or a 6802 Automatic Switch Control.
Transfer is achieved in about 6 seconds with a Micro-AT control or a 6802 control. Split-bus application is possible with two 6802 controls. A 6802 control can be integrated into an IntelliTeam® SG Automatic Restoration System. Serves up to three critical loads.
System VI Switchgear is available through 38 kV, 630 A continuous and load dropping, and up to 25 kA RMS symmetrical short-circuit. It includes motor-operated load-interrupter switches plus a Micro-AT® Source-Transfer Control or a 6802 Automatic Switch Control.
Transfer is achieved in about 6 seconds with a Micro-AT control or a 6802 control. Split-bus application is possible with two 6802 controls. A 6802 control can be integrated into an IntelliTeam® SG Automatic Restoration System.
The switchgear serves any number of critical loads, and it can be furnished with a variety of metering options.
Power-Operated Custom Metal-Enclosed Switchgear
Power-operated Custom Metal-Enclosed Switchgear is available through 38 kV, up to 2000 A continuous and up to 40 kA short-circuit. The switchgear includes Mini-Rupter® Switches with MS-2 Switch Operators or Alduti-Rupter® Switches with AS-30 Switch Operators, plus a Micro-AT® Source-Transfer Control.
Transfer is achieved in as little as 20 to 25 cycles with Mini-Rupter Switches or in about 3 seconds with Alduti-Rupter Switches.
Common bus or split bus. Serves any number of critical loads. The switchgear can be furnished with a variety of metering options and with a second Micro-AT control to permit transfer to a back-up generator.
Pad-Mounted Style IntelliRupter® PulseCloser® Fault Interrupter
The pad-mounted style IntelliRupter PulseCloser Fault Interrupter is available through 27 kV, 630 A continuous and up to 16 kA interrupting.
When furnished with the IntelliTeam® SG Automatic Restoration System or fiber-optic modems, transfer is achieved with two IntelliRupter® fault interrupters in 1.5 to 1.8 seconds. Using the loop-restoration feature, transfer is achieved with two IntelliRupter fault interrupters in 0.6 to 0.8 seconds.
Not limited to two-way transfer, IntelliRupter fault interrupters include sensors for three-phase monitoring of line current and three-phase monitoring of voltage on both sides of the switch.
Communicating IntelliRupter fault interrupters can be integrated into an IntelliTeam® SG Automatic Restoration System.
Summary of Solutions for Underground Systems
| Switching Device | Voltage, kV | Continuous and Load Dropping Current, Amperes | Short-Circuit Current, kA, RMS, Sym. | Maximum Number of Critical Loads | Type of Control | Common-Bus Maximum Source-Transfer Time | Suitable for Split-Bus Application? | Suitable for IntelliTeam SG Integration? |
|---|---|---|---|---|---|---|---|---|
| Source-transfer pad-mounted gear | Up to 27 | 600 | Up to 14 | Up to 2 | Micro-AT control | 0.5 sec | No | No |
| 6802 control | 3 sec | No | Yes | |||||
| Source-transfer Vista switchgear | Up to 38 | 630 | Up to 25 | Up to 3 | Micro-AT control | 6 sec | No | No |
| 6802 control | Yes, with two 6802 controls | Yes | ||||||
| System VI Switchgear | Up to 38 | 630 | Up to 25 | Any Number | Micro-AT control | 6 sec | No | No |
| 6802 control | Yes, with two 6802 controls | Yes | ||||||
| Power-operated custom metal-enclosed switchgear | Up to 38 | Up to 2000 continuous; up to 1200 load-dropping with Alduti-Rupter Switches | Up to 40 | Any Number | Micro-AT control | 20 to 25 cycles with Mini-Rupter Switches; 3 sec with Alduti-Rupter Switches | Yes, with a Micro-AT control | No |
| Pad-mounted IntelliRupter PulseCloser Fault Interrupter | Up to 27 | 630 | Up to 16 | Any Number | Integral | 1.8 seconds using IntelliTeam SG system and approved communication devices, 0.8 seconds using loop restoration | Yes | Yes |
A Choice of Automatic Source-Transfer Controls
Some of S&C’s automatic source transfer solutions include a Micro-AT® Source Transfer Control. Others include a 6800 Series Automatic Switch Control. And some are available with either device. IntelliRupter® PulseClosers feature their own proprietary control group which can provide automatic source transfer functionality.
So what’s the right control for your application?
Micro-AT® Source-Transfer Control
Micro-AT Source-Transfer Control was specifically developed for automatic source transfer and is very easy to configure. No personal computer is needed. But with a PC, you can download events from the optional communications card of the control.
Remote indication and control functions are also available on the Micro-AT Control. If communication to SCADA is required, a separate remote terminal unit must be furnished.
6800 Series Automatic Switch Controls
6800 Series Automatic Switch Controls combine a switch control, remote terminal unit, and battery management system/ automation control in a single package. In addition to automatic source transfer, these controls can provide automatic sectionalization. And they can be integrated into an IntelliTeam® SG Automatic Restoration System, permitting load restoration from multiple sources.
6800 Series Automatic Switch Controls are ideal for applications where the two utility sources can’t be physically brought to the same unit of switchgear. The controls communicate with each other and to SCADA via radio or fiber-optics, using DNP3 protocol. A personal computer is required to configure the controls and analyze events.
IntelliRupter® PulseCloser® Fault Interrupter
IntelliRupter PulseCloser Fault Interrupter includes a control group consisting of a protection and control module and a communication module. In addition to automatic source transfer — with or without a SpeedNet™ Radio — the control group permits application in an IntelliTeam SG Automatic Restoration System, as well as automatic loop restoration and SCADA applications. The control group is configured and operated via secure WiFi connection to a personal computer.