Guide 1-PATIENT SECURITY

In this laboratory guide, you approach the protection of the patient by evaluating the electrical parameters, as well as the types of ground, neutral and phases.

GlOSSARY

Arc burns: Result from high temperatures (up to 35000 F) when an arc flash event occurs.

Arc Flash: Simply put, an arc flash is a phenomenon where a flashover of electric current leaves its intended path and travels through the air from one conductor to another, or to ground. The results are often violent and when a human is in close proximity to the arc flash, serious injury and even death can occur.

Current: The rate of flow of electricity in a circuit. Measured in amperes. The symbol for current is the letter I.

Electrical burns: Happen when electric current flows through tissues and organs. Electrical Shock: Occurs when the body becomes part of an electrical circuit. Shocks can happen in three ways.

• A person may come in contact with both conductors in a circuit.

• A person may provide a path between an ungrounded conductor and the ground.

• A person may provide a path between the ground and a conducting material that is in contact with an ungrounded conductor.

Electricity: Is the flow of electrons through a conductor.Ground: Is the Conductor that normally doesn’t carry current, if the circuit work well. It’s connected to the ground network of the building, and serves to dislodge possible leaks or current branches to the ground electrodes. The color of its insulation is yellow and green.

Insulator: A material that does not give up free electrons easily and offers opposition to current flow. Some of the best insulators are polystyrene, mica, glass, and wood.

IT System: The transformer neutral is not earthed, but is theoretically unearthed. In actual fact, it is naturally earthed by the stray capacities of the network cables and/or voluntarily by a high impedance of around 1,500 Ω (impedance earthed neutral); the electrical load frames are earthed. should an insulation fault occur, a low current develops as a result of the network’s stray capacities. The contact voltage developed in the frame earth connection (no more than a few volts) is not dangerous. if a second fault occurs on another phase before the first fault has been eliminated.

Live: Is the active conductor that carries current from electric box to different points of light and sockets. The color of its insulation can be brown, black and gray.Neutral: Is the return conductor that closes the circuit, allowing the return of the current from the points of light and sockets. The color of its insulation is always blue.Safety: A device to prevent injury, when too much electricity enters the circuit, the safeties come on and cut off the flow.

Thermal burns: Typically happen when skin touches a hot surface.

TN System: The transformer neutral is earthed; the electrical load frames are connected to neutral. This type of system has three possibilities: the same conductor acts as a neutral and a protective conductor: this is the TN-C system; the neutral and the protective conductor are separate: this is the TN-S system; and the combination of these two systems, known as TN-C-S when the neutral and the protective conductor are separated downstream of part of the installation in the TN-C system. Note that the TN-S cannot be placed upstream of the TN-C. An insulation fault on a phase becomes a short circuit and the faulty part is disconnected by a Short-Circuit Protection Device (SCPD).

TT System: The transformer neutral is earthed; the electrical load frames are also earthed. The current of an insulation fault is limited by earth connection impedance. Protection is provided by the Residual Current Devices (RCD): the faulty part is disconnected as soon as the threshold IΔn, of the RCD placed upstream, is overshot by the fault current.

WORKSHOP

• What is Electrical Safety?

The electrical safety is the reduction of the risk of harmful effects that can be used by the application of technologies that involve the use of electrical equipment or the use and dependence of electricity, this has generated accidents by contact with energized elements, or explosions. To avoid these risks, it is necessary to know the main causes associated with electricity and how to control them.

• How can you describe a hazard?

A danger is any situation that represents a risk to the health of a person, among the main electrical risks according to the technical regulation of electrical installations (RETIE) are:

1. Electric arc:

It is considered a cause of fires of electrical origin. It is caused by bad contacts, opening of circuits with load, failure in safety distances, rupture of insulation, contamination or short circuits.

2. Absence of electricity:

The cause is due to power cuts or deficiencies of the devices where the medical equipment is connected.

3. Direct contact:

The cause is due to the negligence of people who work with equipment or energized parts or inadequate exposure of energized elements.

4. Indirect contact:

The cause is because there are insulation faults, absence of maintenance, or defects of the ground conductor. An insulation deterioration by an overcurrent stresses parts exposed to human contact.

5. Overloads:

It occurs when the current excedes limits of the driver, or equipment; iven by increases in load to the capacity of the installation, by drivers inappropriate, connections with bad contacts and parasitic currents not considered in the designs.

6. Short circuit:

It occurs due to insulation faults, strong winds, collisions with structures that support energized conductors.

• How can you prevent an Electrical Burn?

• Describe what types of earthing system do you know.

Grounding systems are a set of elements for a protection system in installations and equipment connected to the grounding system, against overloads, over voltages, current leaks, and atmospheric discharges directing them directly to the ground.

DEVELOPMENT

PROCESS

What was done?

The students first must take off any metallic accessory, clipping hair for the personal protection each one. Using tester screwdriver and multimeter the student can identify Neutral, ground and live wire.

How to identify the live and neutral with a tester screwdriver?

With tester screwdriver the students can identify the live and neutral wire the next way, they hold tester screwdriver with their fingers on the insulated part. With thumb over on the insulated part of the tester, insert the end of this into the holes in socket, in hole where tester turn on is the live and in the hole where turn off tester is neutral.

How to identify the live and neutral with a multimeter?

The students put their multimeter in AC voltage, after they take the black tip with their fingers and the red tip insert in the holes of socket, which give them a voltage greater than 10 V is live.

The use of the tester screwdriver and multimeter is necessary when the phase and neutral holes are of the same size and can’t be identified visually.

Also the students measured the voltage betwen neutral - live, live - earth and earth -neutral, using the multimeter. The correct way to measure these unions is to put the tips of multimeter in the holes of socket respectively.

RESULTS

The results obtained in this practice show below: ting them directly to the ground.

The results obtained between LIVE-NEUTRAL and LIVE-EARTH are those expected in both the hospital and industrial environments, because the theoretical value should be for both cases of 120VAC. On the other hand, the result between LIVE-NEUTRAL was much lower than expected, this because the grounding in the laboratory where the practice was performed is failing; this may be due to different causes, one of these may be copper wire failure, which would only affect a part of the building.

CONCLUSIONS

1. The laboratory where the practice was performed, has faults in the grounding, this due to different causes, one of these can be failure in the copper wire , which would affect only a part of the building.

2. Trough the literature it was identified that the ground provides protection against possible failures in the insulation of the equipment and allows any electrical discharge to be earth..

3. Is considered that an IT isolated system offers more reliability and availability to the biomedical equipment installed in clinical areas, guaranteeing the safety of the patient and the healthcare personnel.