HVAC stands for heating, ventilation, and air conditioning. In computing and especially in enterprise data centers, HVAC systems control the ambient environment (temperature, humidity, air flow, and air filtering) and must be planned for and operated along with other data center components such as computing hardware, cabling, data storage, fire protection, physical security systems and power.



transfer1Raritan’s hybrid rack transfer switch system is the first in the world to offer both electromechanical relays and silicon-controlled rectifiers (SCRs) to overcome the limitations of a traditional automatic transfer switch (ATS).

Raritan’s Rack Transfer Switch

Current sampling at 4,800 times per second for load transfers within 4 to 8ms.

Oversized relays, rated at 48A, and SCRs, rated at 70A, even though the transfer switches are intended for 16A and 32A loads.

Relay contact air gap of 3.3mm vs. the 0.6mm gap used in most transfer switch relays on the market to prevent electric arcing.

Two single throw relays instead of one double throw relay (a single point of failure) to support reliable out-of-phase transfers.

Inlet, outlet, and branch circuit level metering.

Remote outlet switching.

transfer2Available in 16, 32 and 63A, with a nominal voltage of 230 V, Chloride CROSS Rack exists in both single-phase input and single-phase output models. All models are designed for installation in 19-inch closed standard rack cabinets, occupying 2U in vertical rack space with a protection degree of IP21.

Ability to switch between two alternative single-phase power sources, ensuring redundant power to critical loads.

The ‘fixed priority’ operational mode, allows the preferred input line to be selected, enabling automatic transfer of the load to the priority line whenever its parameters fall within certain values.

BBM modality on both poles, thus ensuring that the two sources will never be directly connected.

CBEMA guidelines are met due to Chloride CROSS Rack™ ability to switch between independent AC power sources in both synchronous and asynchronous conditions, relative to the input waveforms.

Emergency switching, provides the transfer to the alternative source, in only a few milliseconds.

Ability to recognize downstream short-circuits that are caused by loads or distribution.

transfer3The Server Technology Metered Fail-Safe Transfer Switch provides fail-over redundancy to single or dual-power supply servers and network devices. Exclusive to the Metered Fail-Safe is its ability to carry loads on the A circuit, B circuit or both.

Similar, but unlike a common automatic transfer switch, the Metered Fail-Safe unit is unique in that it contains two (2) in-feeds and two (2) banks of outlets.

For example he “A” in-feed routinely powers just the A1-8 outlets, and the “B” in-feed routinely powers just the B1-8 outlets. However, if the “A” in-feed goes down, the “B” in-feed powers all 16 outlets and the same if the “B” in-feed goes down, the “A” in-feed powers all the outlets.

This “Fail-Safe” method has several advantages compared to a standard ATS because it does not prohibit load balancing between the two supplied circuits. A standard ATS contains two-in-feeds, but runs all outlets from just one source, with the secondary source only being used once an outage occurs on the capacity. This results in less heat, less resistance, and consequently less of a voltage drop compared to the same load existing on just one source. Only when an outage occurs on one of the two sources will the entire load be applied to a single source.

Geist’s auto transfer switch provides redundant power for single-corded data center equipment. If the primary power source experiences failure, the transfer switch automatically shifts to a secondary source, ensuring uninterrupted service. Once the power from the primary source is restored, the unit automatically switches back to the original source of power.

transfer4The auto transfer switch features include:

Auto switching relay

Double pole, double throw (DPDT) relay switching

UL relay contact rating of 35 Amps at 277 Voltage in Alternating Current (VAC)

Life expectancy at rated load of 100 thousand operations

Operate time is less than 25 milliseconds

Release time is less than 25 milliseconds

Pick up is 85 percent or less of nominal

Power feeds A and B must be phase synchronized

UL and c-UL listed 60950

transfer5The ASCO 7000 Series Power Transfer Switch is available in the conventional, two-position transfer configuration, and closed or delayed transition modes of operation. Additionally, switched or overlapping neutral options provide for reliable operation of ground fault protection systems and reduction of voltage transients from unbalanced load switching.
transfer6The ASCO Service Entrance Rated transfer systems are designed for automatic switching of loads between the utility source and an alternate source of power. The transfer system also contains a disconnect device on the normal source, including a disconnect link on the utility neutral, and a disconnect link between neutral and ground. If the utility source is Y connected, the voltage is greater than 250 volts phase to neutral and the system continuous current is greater than 1000 amperes, the utility disconnect device will be equipped with ground fault trip.
transfer7The ASCO 7000 Series Service Entrance Power Transfer Switch combines automatic power switching with a disconnect and over current protective device on the utility source. It uses the same reliable transfer switching mechanism and controller as the 7000 Series product platform. It also includes a utility circuit breaker as a disconnect device and links for connecting both neutral and ground conductors.
transfer8The ASCO 7000 Series Soft Load Power Transfer Switch synchronizes and parallels two independent power sources without interrupting power flow. The switch can be programmed to either maintain parallel operation of both power sources, or transfer the load to the onsite generating unit, avoiding transients caused by block loading.
transfer9ASCO 7000 Series Medium Voltage Transfer Switch protects medium voltage loads by offering maintainable and highly proven power transfer switches. The switches can be configured with protective relays and other options to meet specific project requirements. Switching at medium voltage is often preferred when most loads in a facility require protection, or when protected power is needed at distances. By placing the switch near the source, often outside, and often with service entrance, many costly installation complications can be avoided.

transfer10The ASCO Two-Source Systems are designed for automatic switching of loads between the utility source and an alternate source of power. Upon the loss of the utility power source, the system provides an automatic start signal to the alternate source of power. Once the alternate source has reached proper voltage and frequency, the system transfers the critical load from the utility source to the alternate power source. When normal power is restored the controls will retransfer the load to the utility and signal shutdown of the alternate power source after allowing a cooldown period.

The ASCO Two-Source Systems include an automatic transfer switch, any or all of the following options; automatic engine starting controls, overcurrent protection for both emergency and normal sources, instrument meters, status annunciation, and audible alarm. The systems are designed to NEMA switchboard construction and are labeled to UL 891 standards.

transfer11The ASCO Three-Source Systems are similar to ASCO Two-Source Systems except that a second alternate power source is added to back up the first if that power source fails. Upon the loss of the utility power source, the system provides all necessary controls to start both alternate power sources. The critical loads are automatically transferred to the first alternate power source that achieves acceptable voltage and frequency. The second alternate power source is then automatically shutdown after a time delay and cool down period.

If the first alternate power source fails, the second alternative power source will be automatically re-started and the load will be transferred from the first alternative power source to the second alternative power source. When the normal power is restored, the controls automatically retransfer the load to the utility power source.

transfer12For maximum availability applications, Liebert STS2 static transfer switch provides an automatic, seamless transfer between your critical load and the outputs of two independent UPS systems in a dual-bus power configuration. If the primary UPS should fail, the switch will automatically transfer the loads to the alternate UPS.

The Liebert Static Transfer Switch 2 (STS2) is available in 100A, 250A, 400A, 600A, 800A and 1000A sizes, 60Hz or 50Hz field selectable. Multiple input voltages are available. The system provides an automatic, seamless transfer between the outputs of two independent UPS systems and the input of a critical load in a dual-bus power system.

transfer13The Liebert STS2/PDU from Emerson Network Power is making it easier to protect your critical equipment by giving your single cord loads the reliability of dual cord power or by providing added redundancy to your dual cord devices. With a single, space-saving unit, the Liebert STS2/PDU static transfer switch/power distribution unit provides power distribution and automatic switching between two different AC power sources.

The Liebert STS2/PDU is available in 250A, 400A, 600A and 800A systems, in both 60Hz and 50Hz frequencies. Multiple input voltages are available. Designed for use in dual-bus power applications, this solution combines fast switching between AC power sources, power isolation, distribution, monitoring and grounding into a single package.