Modern electronics are used in many sensitive areas today – for example, in medical facilities, laboratories or industrial plants. Precision and functionality are not the only requirements in such environments. Safety and fault-free system stability are just as important.
Electrical connections in particular often present underestimated risks. Overvoltage, grounding conflicts or electromagnetic interference can affect or damage sensitive equipment. Data loss and, in the worst case, personal injury are also possible consequences.
TTL network galvanic isolators provide effective protection. They reliably isolate electrical systems from each other, preventing the transmission of dangerous currents or voltage spikes between devices. At the same time, they enable loss-free signal transmission – even under demanding operating conditions.
What is galvanic isolation?
Galvanic isolation electrically isolates the circuits between two devices from each other without hindering the exchange of signals. The separation of the electrical potentials is created by a barrier made of a non-conductive material so that no electrical current can flow between the circuits.
This isolation barrier significantly reduces or prevents interference and damage in electrical systems that could otherwise be caused by various factors, such as potential differences, surges, noise or ground loops. Another important factor is the protection of persons from electric shock.
Galvanic isolation in the network cable
What can cause dangerous voltages in the network cable?
Particularly in copper-based network cabling, installation or design errors, aging processes or moisture can cause line cores or the cable shield to unintentionally establish an electrical connection to other live parts. In supply networks, high overvoltages can occur for short periods, so-called voltage transients.
How does a network isolator work?
The network isolator creates a physical barrier that breaks all electrically conductive connections between the connected network peripheral and the connected device. In use, it provides reliable protection against DC and AC voltages of 4 KV and more, ensuring seamless operation of the network. In addition, it enables virtually lossless transmission of high-frequency AC voltages used in the Ethernet protocol for signal transmission, maintaining transmission quality.
Where are network isolators usually used?
Medical technology
patient protection against potentially hazardous leakage currents that can occur between a medical-electrical device device when connecting to an Ethernet network or a non-medical device (PC or printer).
Measuring and monitoring systems
Sensitive devices in electrical test fields that are connected to a control station via Ethernet interfaces must be protected against interference voltages and potential differences.
Computer systems
For computer systems that are galvanically connected to each other over long distances via Ethernet cabling and where potential equalization currents are to be prevented.
Valuable equipment and equipment requiring protection (general)
Applications where valuable equipment or equipment requiring special protection must be protected from hum and overvoltages
from the network periphery.
When is the use of a network isolator not recommended?
The network isolator has a specific frequency bandwidth of 0.3 MHz to 100 MHz for data transmission. Frequencies outside this bandwidth experience significant attenuation. Therefore, signals from nurse call systems, PBX systems, and analog audio or video signals cannot be transmitted sufficiently via the network isolator.
Important: A cable route connected to a network isolator cannot be used to supply power to PoE (Power over Ethernet) end devices!
Galvanic separation in medical technology
What defines a medical electrical device or system?
The definition of medical electrical (ME) equipment is determined by the international standard IEC 60601-1. The function of an ME device is to support diagnostic, therapeutic, care or monitoring measures for patients. The term „medical-electrical system“ describes the cooperation of several devices, at least one of which must by definition be a medical-electrical one. The individual components of the ME system can communicate with each other both wired and wirelessly.
Why do medical electrical systems need network isolators?
ME devices pose a high safety risk to the patient due to their proximity. Electrical currents that pass to the person via the electrically conductive parts of the device can lead to life-threatening situations. To eliminate any risk that could endanger a person, the international standard IEC 60601-1 regulates the requirements for the electrical safety of ME equipment and ME systems. As a general rule, all electrical equipment – including nonmedical
equipment – located in the immediate vicinity (1.5 m radius) of the patient or connected to other equipment in the patient environment must comply with the electrical safety requirements of the German standard DIN EN 60601-1.
To achieve compliance with the standard, ME devices and ME systems that are connected to other devices or networks via signal interfaces such as Ethernet, RS232 or USB must have galvanic isolation devices in the supply lines. Among other things, the standard requires that all live lines leading to the device from an electrically unprotected area must be connected via a disconnecting device.
ME devices must have a galvanic isolator at their Ethernet interface. If this is not integrated at the factory, the use of a network isolator is required. This also applies if an Ethernet interface on an ME device is intended exclusively for connection to other ME devices and therefore does not have its own galvanic isolation. In cases where the Ethernet interface is connected to a non-ME device (e.g. to a printer), a network isolator must also be interposed.
What is MOPP?
MOPP is the abbreviation for Means of Patient Protection and is defined in the IEC 60601-1 standard as a „measure to reduce the risk of electric shock to the patient“. Medical devices must be equipped with two independent protective measures for patient protection in the event that one of them fails.
Here, several protection systems usually act in parallel or in combination to counteract different hazard potentials. The voltage values required by a network isolator are defined in 1 MOPP and 2 MOPP:
The number of protective measures that a network isolator offers in individual cases depends on its technical properties and the specific medical application scenario. For example, a blood pressure monitor has different requirements than a pacemaker in an operating theatre. In addition, a network isolator only has to offer both protective measures if the medical device to be protected is not already equipped with a protective measure.
Is it possible to connect several network isolators in series?
In environments with increased risks such as operating theatres, it may be advisable to equip both the medical device and the wall outlet with a galvanic isolation device. In other cases, medical devices that already have a galvanically isolated network interface may need to be operated on wall outlets that are also galvanically isolated. Such a configuration is normally harmless, as network isolators from TTL network do not usually have a significant effect on signal strength and quality.
Can a network isolator be used in a PoE network?
A network isolator can be easily integrated into a PoE network without negatively affecting its functionality or structure. However, it should be noted that PoE end devices cannot be supplied with power via the network isolator due to the galvanic isolation. There are two possibilities for operating PoE devices: Either the network isolator is removed from the line or the PoE device is supplied with power via a separate, possibly medical power supply unit.
Network securely now
Whether hospital, test field, laboratory or production hall – galvanic isolators protect systems from failure, extend the service life of devices and effectively secure data communication. In the reichelt online shop, we stock various TTL network galvanic isolators with RJ45 or USB interface, for top-hat rail mounting or in keystone format. All products are TÜV-tested (an independent German testing body) and comply with the IEC 60601-1-2MOPP standard.
Images: TTL network, Adobe Stock
