Product category:
Power supplies and plant cabling
News Release from: Siemens Automation and Drives | Subject: 7LQ3 354 and 7LQ3 355
Edited by the Processingtalk Editorial
Team on 07 March 2008
Monitoring secure power supply earth
leakage
For early detection and correction of insulation faults, the Siemens now offers two new rack-mounted insulation breakdown monitors and alarm units
These units monitor non-grounded vital power supplies, for example in pharmaceutical or in medical premises, detect insulation faults as soon as they occur, and output warning signals The units are applied to the vital power supplies on equipment that must remain in operation even when threatened with a short-circuit to frame, or when the general power supply fails
This article was originally published on Processingtalk on 10 Apr 2006 at 8.00am (UK)
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The 7LQ3 354 and 7LQ3 355 insulation monitors guarantee this by monitoring the insulation resistance of the non-grounded power supply as well as the load current and the temperature of a transformer.
On the 7LQ3 354, the alarm value of the insulation resistance is 50 kilo-ohms (fixed).
The 7LQ3 355 monitor also offers an adjustable response threshold of 50 to 500 kilo-ohms.
In addition, a line of colour LEDs indicates the current insulation status between 20 kilo-ohms and 1 mega-ohm.
Users can thus see the plant status at a glance.
Changeover contacts can be used to connect the devices to the building automation system or to the relevant equipment monitoring system.
The insulation monitors can even be installed in existing systems.
The 7LQ3 355 monitor is compatible with the 7XV93 test and signaling combinations from Siemens.
If the voltage drops below 90 percent of the rated value, the 5TT3411 and 5TT3412 voltage relays transmit the signal for switching to a second mains supply to secure the continued operation of the equipment.
The units are suitable for the secure power supply of sensitive areas such as server systems, etc.
The new voltage relays are suitable for single-phase (5TT3411) and three-phase (5TT3412) supply systems.
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