Part 1 in our Series on How to Protect Medical Equipment from Faulty and Unreliable Electrical Power 

Diagnostic Imaging Equipment is highly sensitive to electrical power problems. Massive electrical events such as lightening strikes and total power failures can cause immediate and catastrophic damage to boards, connectors, tubes and other expensive replacement parts on a machine. Most often, though, the same damage will be caused by small flickers, surges, swells, or brownouts, as the electrical components of a machine are overtaxed, worn out, and frayed to the point that a chain of parts failures occurs.

Understanding the different kinds of power problems your medical equipment can be subjected to will help you to identify and prevent potential problems — before you’re hard down and faced with big repair bills, cancelled patient appointments, or glitches in the middle of a procedure. 

Common power quality disturbances include surges, spikes, swells, sags or brownouts, noise and outages. All of these power disturbances can cripple the equipment and place the care of the patients at risk.


Flicker — a momentary outage that causes brief service interruptions, lasting less than 60 seconds. They can briefly shut down the electronic devices and appliances in your facility. When your digital clock or DVD player blinks or your lights go off for a few seconds, you’ve experienced a flicker. Flickers can be caused by a number of things: 

» Lightning strikes

» Tree branches making contact with power lines

» Vehicle accidents involving electrical equipment

» Construction accidents involving powerlines

» Salt spray affecting FPL equipment

» Damage to underground equipment

Here’s how it happens: Let’s say a tree branch (or, here in Florida, a palm frond) is blown into overhead power lines. When the branch makes contact with the power company’s lines (A), the system detects the interference and shuts off electricity to that section of the line for a brief period – usually a few seconds (B). The tree branch or palm frond typically falls to the ground, allowing service to be restored quickly. Electronic devices may shut off and need to be reset. According to Florida Power & Light, this process allows the system to determine if there is a break in the line or other electrical difficulty. Briefly shutting off power and isolating the problem area helps prevent damage to the electric system, which could result in a longer outage and affect many more customers.

Surge – a rapid short­ term increase in voltage. Surges often are caused by unexpected burdens on the electrical system, often from lightning, in which a brief but intense increase in the amount of electricity occurs. A surge can even happen when high power demand devices such as air conditioners turn off and the extra voltage is dissipated through the power line. Since sensitive electronic devices require a constant voltage, surges stress delicate components and cause premature failure.

Spike – an extremely high increase in voltage with a very short duration measured in microseconds. Spikes are often caused by lightning or by events such as power coming back on after an outage. A spike can damage or destroy sensitive electronic equipment. Equipment should be turned off during a power outage. Wait a few minutes after power is restored before turning it on and then turn on one device at a time.

Swell- a short-term increase in voltage. A swell can lead to stressed or damaged electronic components, which cause premature equipment failure.

Sag – also called brownout, is a rapid short-term decrease in voltage. A sag typically is caused by simultaneous high power demand of many electrical devices such as motors, compressors and so on. The effect of a sag is to starve electronic equipment of power causing unexpected crashes and lost or corrupted data. Sags also reduce the efficiency and life span of equipment such as electric motors.

Noise – a disturbance in the smooth flow of electricity often referred to as electro­magnetic interference (EMI) or radio frequency interference (RFI). Noise can be caused by motors and electronic devices in the immediate vicinity or far away. Noise can affect performance of some equipment and introduce glitches and errors into software programs and data files.

Outage – also called a blackout, is a total loss of power for some period of time. Outages are caused by excessive demands on the power system, lightning strikes and accidental damage to power lines. In addition to shutting down all types of electrical equipment, outages cause unexpected data loss. A partial power outage, in which the power goes out in only part of your facility, may be caused by a tripped circuit breaker, a blown fuse, or a broken connector or wire at one of the service leads to the building.


Flickering Lights — Possible Causes are a Sag, Swell, or Flicker

Electrical Equipment Issues — Possibe Causes are a Surge or Spike

Air Conditioning Interruption — Sag, Swell, or Flicker

Shrunken computer or TV picture — Sag

Computer turning off and on — Flicker

No electricity in the entire home or business — Power Outage

No electricity in one room — Partial Power Outage

Stay tuned to this blog for our next installment on “How to Protect Diagnostic Imaging Equipment from Bad Power”