What is an IEC 60601-1 medical grade rated power supply AC adapter?

An IEC 60601-1-2 medical grade rated power supply AC adapter converts input line voltage from the wall to a lower voltage, typically DC, which is used to operate and end use piece of medical equipment. IEC 60601-1-2 medical grade power supply AC adapters are typically housed in a plastic enclosure and are available with both 2 and 3 prong input options. power supplies are also available as open frame for use inside of medical equipment. These AC to DC converters are designed in accordance with international medical standards and provide for compliance with certain aspects of them which differs from generic information and communication technology equipment power supplies.

Why is my medical grade IEC 60601-1 power supply certified to IEC 60601-1 3rd Edition while the latest standard is IEC 60601-1 4th Edition?
IEC 60601-1 has different sections in specifications for safety and EMI/EMC. The latest revision of the safety portion of  IEC 60601-1 is 3rd Edition while for EMI/EMC the latest revision is 60601-1-2, 4th Ed. 

What is the effective date of 60601-1-2, 4th Ed?
60601-1-2, 4th Ed. was effective on December 31, 2018.

What's the difference between an IEC 60950-1 and IEC 60601-1 medical grade rated power supply?

IEC 60950-1 and IEC 60601-1-2 power supplies are both AC to DC converters and may be either internal or external but are designed to different specifications to match the end system specifications. While the basic performance behaviors are similar such as input and output voltages and mechanical configurations, there are many differences as well. Some of the key differences are that medical IEC 60601 medical grade AC to DC adapters are able to withstand a higher dielectric withstand voltage and must have lower leakage current.  There are many other differences and also considerations to consider depending on the end use application.  

What MOOP and MOPP?
Medical devices must incorporate one or more Means of Protection (MOPs) to isolate patients and operators from the risks of electrocution. A Means of Protection (MOPs)  can be safety insulation, a protective earth, a defined creepage distance, or an air gap or other protective impedance. These can be used in various combinations. IEC 60601-1 3rd edition differentiates between the risk to patients and the risk to operators. A MOP can therefore be classified as Means of Patient Protection (MOPP) or a Means of Operator Protection (MOOP). The main difference between one MOOP and one MOPP is primarily one of permissible creepage distance. Both requirements are satisfied using Basic insulation. To achieve 2 x MOPP qualification the isolation test is particularly demanding at 4000 Vac and the creepage distance of 8mm is twice that required for one MOPP. 

What is a BF and CF rated an IEC 60601-1-2 medical grade rated power supply AC adapter and what is the difference?

Medical grade power supplies and AC to DC adapters are categorized into one of three applied parts types: body type (B), body floating type (BF), and cardiac floating type (CF). These applied parts require specific attributes such as isolation voltage, creepage and leakage current. Floating refers to an ungrounded power supply, Class II, that is not referenced to another output and is fully isolated. Type B refers to devices that operate within the patient's vicinity, as described in IEC 60601-1 as six feet around a patient's chair or bed and do not touch the patient electronically and are grounded. These devices include operating room lighting, hospital carts and beds, automated dispensers of medication and supplies, and diagnostic equipment like x-ray machines. Type BF devices deliver electrical energy signals to or from the patient such as electrosurgical devices, endoscopes, and electrical vital sign monitors like thermometers. Type CF devices are similar to BF, except they supply power to devices connected to the heart, such as a defibrillator, external pacemaker or intracardiac ECG electrodes and Type CF requires a higher degree of protection against electrical shock than BF types.  
 

How Does an AC-DC Adapter Work?

The AC to DC adapter or external power supply consists of a power supply which is enclosed in a housing similar to an AC plug, hence the term plug type, wall plug in, plug-in or plugtop power adapter. The power supply is plugged into the mains socket and the AC Voltage is then converted by the AC to DC adapter power supply into a DC voltage that is fed into the appliance via the output cable connection.