Electrical Connections, 24VAC | Liebert MR1 manual

Electrical Connections

Caution: Ensure Environmental unit has sufficient 24VAC power to support the MR1, Liqui-tects or any other auxiliary device.

The MR1 Mini-Remote requires a two-wire connection (field- supplied) to communicate with the Environmental unit under its control. The stranded twisted-pair connects to the MR1 interface board at TB2-11 (T+) and TB2-12 (T-). Refer to Table 1 below for the connections at the Environmental unit. Note that maximum length for RS-422 communications is 1000 feet, and minimum of 22 gauge wire should be used for all field wiring.

Power for the MR1 is supplied to TB3-1 and TB3-2. Maximum current draw is 0.3A at 24VAC. It is recommended that the MR1 be powered independently from an external 24VAC transformer; optionally, it may draw power from the Environmental unit. However, if the MR1 is located greater than 300 feet (100 meters) from the Environmental unit, an external transformer must be used.

Liebert		24VAC	Connection to MR1
Environmental		Auxiliary	TB2-11 (T+)
Controller		Power	TB2-12 (T-)

SM - Standard
AM/AG - Advanced		Terminal T5	Terminal 78		(T+)
L10 - Level 10		Terminal G5	Terminal 77		(T-)
Microprocessors

L00 - Level 00		TB1-1	Terminal 78		(T+)
Microprocessor		TB1-5	Terminal 77		(T-)
Mini-Mate 2	-		TB4-1	(T+)
			TB4-2	(T-)

SSC - Small System	-		TB2-1	(T+)
Controller			TB2-2	(T-)

Table 1: Connection Summary

NOTE: New Feature. The inputs are now contact-closure – 24VAC powered inputs are no longer necessary.

NOTE: Exercise caution if installing new MR1 as replacement unit: remove power from signal inputs, or damage to unit may occur!

The MR1 provides a Common Alarm Output, at TB2-9 and TB2-10. This dry-contact is rated for 5A, at 24VDC or 120VAC.

There are four optional Customer Alarm inputs that may be used on the MR1 (see Hardware Configuration). The inputs are triggered by contact-closures, and the contacts are rated for 5A, at 24VDC or 120VAC as well. The connection points and display mapping are as follows:

Local Alarm 1:	TB2-3	&	TB2-4
Local Alarm 2:	TB2-1	&	TB2-2
High Water Alarm:	TB2-5	&	TB2-6
High Head Alarm:	TB2-7	&	TB2-8

Liebert MR1 • 5

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PRODUCT

MR1 specifications

The Liebert MR1 is a state-of-the-art precision cooling unit specifically designed for data centers and critical IT environments. It is engineered to provide optimal temperature and humidity control, ensuring the reliability and longevity of IT equipment. The Liebert MR1 stands out due to its advanced features, technologies, and characteristics, which cater to the growing demands of modern data centers.

One of the main features of the Liebert MR1 is its modular design. This modularity allows for scalable cooling solutions, providing flexibility to adapt to changing needs. The units can be easily combined to create a system that fits the exact requirements of the facility, accommodating both current and future cooling demands.

The Liebert MR1 employs cutting-edge inverter technology, which enhances the efficiency of the cooling process. This technology enables the compressor to adjust its speed, optimizing energy consumption based on real-time cooling requirements. As a result, the unit can significantly reduce operational costs while also contributing to a more sustainable environment.

Furthermore, the Liebert MR1 is equipped with advanced control systems that allow for precise monitoring and management of temperature and humidity levels. Users can easily interface with the unit through an intuitive digital display, enabling seamless adjustments and setting customized environmental parameters. This level of control is crucial for maintaining the ideal conditions conducive to equipment performance.

Another notable characteristic of the Liebert MR1 is its redundancy features. These include built-in redundancies that ensure continuous operation even in the case of a failure in one unit. This reliability is vital for data centers where uptime is of utmost importance, as any downtime can result in significant financial loss and reputational damage.

In addition to its technical features, the Liebert MR1 is designed for near-silent operation. This makes it an excellent choice for environments where noise levels need to be kept to a minimum, such as in office spaces or critical control rooms.

In summary, the Liebert MR1 is an innovative cooling solution that delivers efficiency, reliability, and flexibility for modern data centers. With its modular design, inverter technology, advanced controls, redundancy features, and quiet operation, it addresses the critical cooling requirements of IT professionals, ensuring that their systems remain operational and effective in any condition.