High Density Medical Power Supplies
VMS Series



Introduction

Welcome to the CUI Product Spotlight on open frame medical power supplies. Learn about CUI's VMS high density medical power supply series, including a description of its available configurations, the VMS's advantages over other medical power supplies, key specifications and possible applications.

Objectives

  • Summarize medical safety requirements for ac-dc power supplies
  • Introduce the VMS ac-dc series and it's available configurations
  • Describe the VMS's key features and specifications
  • Describe typical applications for the VMS series

IEC 60601-1


Equipment required to meet IEC 60601-1 include any application that will be operated within the vicinity of a medical patient.

  • IEC 60601-1 is the “International” standard for electronic devices in medical / healthcare applications
  • Each country may adopt their own deviation of the IEC 60601 standard (such as UL 60601)
  • Most countries have harmonized their standards to match IEC 60601
  • The 3rd edition of IEC 60601-1 was published in 2005 and became effective December 2010
  • The 2nd edition remained in effect through June 1st, 2012 in Europe and Canada; June 1st 2013 in the United States
The differences between the 2nd and 3rd editions concern the “classification” of a medical device, not the design of the power supply utilized in the device.

No Effect to Power Supply Design

The transition from IEC 60601-1 2nd edition to 3rd edition did not fundamentally change the design requirements of the medical power supply. Type “B” and one MOOP applications can be satisfied by non-medical IEC 60950-1 rated power supplies with leakage currents that meet a 500uA limit. Type “BF” and both One MOPP and Two MOOP classified applications can be satisfied by a IEC 60601-1 rated power supply. Type “CF” and Two MOPP classified products can be satisfied with a IEC 60601-1 rated power supply with an additional isolation barrier between the supply and the applied part.

  • Type B applications are satisfied by a non-medical IEC 60950-1 rated power supply with reduced leakage currents. This holds true for One MOOP classifications.
  • Type BF classifications are satisfied by IEC 60601-1 rated power supplies which will continue to satisfy both TWO MOOP and ONE MOPP classifications.
  • Type CF classifications are satisfied by an IEC 60601-1 power supply with an additional isolation barrier between the supply and the “applied part” (that touches the patient). The secondary barrier is typically an isolation transformer or dc-dc converter with 8 mm creepage & double insulation. This holds true for the TWO MOPP classification.


Standby Power Consumption


It is estimated that anywhere from 5-10% of the total power consumed in the United States is through “vampire draw,” power lost while electronic equipment is in standby or sleep mode. Governments have already identified no-load power consumption as a major problem in external power adapters and have enacted regulations accordingly. Although standby power consumption regulations do not currently exist for most internal ac-dc power supplies, greater attention is being paid to this measure in the end equipment that incorporate these modules. The medical electronics market, currently estimated to be $150 billion in size, is expected to grow at a 9% rate or the next 5 years, largely driven by aging Baby Boomers and the growing middle class in the emerging markets such as China and India who can now afford improved medical care. As new medical equipment proliferates into the market, greater attention will be paid by customers and regulators to the energy consumption of these designs. In response to this trend, CUI has greatly reduced the standby power levels in their products to 0.5 watts.

  • 5~10% of total power consumed in the US occurs when equipment is in standby mode
  • Regulations in place dictating no-load power for external power supplies
  • Growing importance in embedded power supplies
  • Medical equipment will have an increasing impact on worldwide energy consumption
  • CUI's 20, 40, 60 and 100 W models offer 0.5 W no-load consumption to address this trend

2nd Edition Device Classifications


If the device is operated within the “patient vicinity”, defined as 6 foot radius around a patient chair or bed, then IEC 60601-1 should be applied.

  • Type "B" operates within the patient vicinity (Body)
  • Type "BF" makes physical contact with the patient (Body Floating)
  • Type "CF" makes physical contact with the heart (Cardiac Floating)

Classification of Equipment (Type B | BF | CF), determines what levels isolation / insulation / creepage / clearance / leakage will be required.

New 3rd Edition Device Classifications

IEC 60601-1 3rd edition changes the way a medical device is classified. The device manufacturer uses an ISO-14971 Risk Analysis / Management process to define 1 of 4 possible "Means of Protection" (MOP) classifications. ISO-14971 specifies a process for a manufacturer to use in order to identify the hazards associated with medical devices, including in vitro diagnostic (IVD) medical devices. The process is used to estimate and evaluate associated risks, control these risks, and monitor the effectiveness of the controls.

The device manufacturer uses an ISO-14971 Risk Analysis / Management process to define 1 of 4 possible "Means of Protection" (MOP) classifications:
  • ONE MOOP: Single “Means of Operator Protection”
  • TWO MOOP: Two “Means of Operator Protection”

  • ONE MOPP: Single “Means of Patient Protection”
  • TWO MOPP: Two “Means of Patient Protection”

IEC 60601-1 Requirements by Classification

The tables below summarize the major requirements of IEC 60601-1 by edition and classification. As highlighted below, isolation, creepage, and insulation are important specifications that must be considered when selecting a medical ac-dc power supply. Regardless of edition or classification, medical devices may not exceed 500uA leakage current and must have dual fused input protection. UL's 60601-1 standard contains a deviation that stipulates a maximum leakage current of 300uA for medical devices.

2nd Edition Requirements by Classification

Classification Requirements
Type B Isolation: 1500 Vac Creepage: 2.5 mm Basic Insulation
Type BF Isolation: 3000 Vac Creepage: 5 mm Double Insulation
Type CF Isolation: 4000 Vac Creepage: 8 mm Double Insulation

3rd Edition Requirements by Classification

Classification Requirements
One MOOP Isolation: 1500 Vac Creepage: 2.5 mm Basic Insulation
Two MOOP Isolation: 3000 Vac Creepage: 5 mm Double Insulation
One MOPP Isolation: 1500 Vac Creepage: 4 mm Basic Insulation
Two MOPP Isolation: 4000 Vac Creepage: 8 mm Double Insulation

Regardless of edition or classification, medical devices may not exceed 500uA Leakage (UL deviation specifies 300uA max) and must have dual fused input protection.

VMS Series Efficiency Curves


The charts above highlight the efficiency curves for the VMS-160's 12 V model and the VMS-365's 12 V model at 115 Vac and 230 Vac inputs. The industry leading power density offered by these models is possible due in large part to typical efficiencies well above 90% at most loading conditions.

Applications

The VMS series can be employed across a wide range of medical applications, including diagnostic equipment, medical monitoring devices, and home patient care equipment. Because the VMS-160 and VMS-365 series also carries IEC 60950-1 ITE safety approvals, designers of non-medical devices such as LED arrays, networking equipment, telecom equipment, and consumer electronic devices can take advantage of the series' high efficiency and compact footprints.

Diagnostic Equipment

Medical imaging, CT scanners, ultrasound


Medical Monitoring

Blood pressure monitor, ECG, EEG


Home Patient Care

Automated bed, CPAP, infusion pump


Non-Medical

LED displays, networking, telecom, consumer electronics

Product Benefits

VMS Low No-Load Power Medical Series

CUI's low no-load power VMS series ranges from 20 to 100 watts and is approved to the IEC 60601-1 standard. The 20 W VMS-20 series is suitable for 2nd edition “BF” and 3rd edition two MOOP classified medical equipment, while the 40 W, 60 W, and 100 W models are designed with an additional isolation barrier, making them suitable for 2nd edition “CF” and 3rd edition two MOPP classified medical equipment. Agency approvals include UL and cUL for North America, as well as TUV approvals for Europe. These models feature compact footprints, high efficiency, and low no-load power consumption, making them ideal for applications where space is limited and minimizing energy consumption is a priority.

  • Efficiency up to 91%
  • Medical (IEC 60601-1) 3rd edition approvals
  • Low no-load power consumption
  • Compact footprints
  • Universal input 90 ~ 264 Vac
  • Over current, over temperature, over voltage protections

VMS High Density Medical Power Series

CUI's VMS-160 and 365 series are high density ac-dc medical power supplies approved to the IEC 60601-1 and IEC 60950-1 standards, making them suitable for 2nd edition “CF” and 3rd edition two MOPP classified medical equipment, as well as ITE, industrial, and consumer electronic applications. Agency approvals include UL and CSA for North America, as well as VDE and Nemko approvals for Europe. With typical efficiency levels of 91%, the models are highly efficient, allowing for an industry leading power density of 19 W per cubic inch. Additional features include active power factor correction, a 12V auxiliary fan output, and a number of protections, including over current, over temperature, and over voltage.

  • Typical efficiency: 91%
  • Full medical (IEC 60601-1) 3rd edition and ITE (IEC 60950-1) approvals
  • Power densities up to 19 W/in3
  • Universal input 90 ~ 264 Vac
  • Active power factor correction
  • Auxiliary fan output: 12 V
  • Over current, over temperature and over voltage protections

Available Products

VMS Low No-Load Power Medical Series

CUI's 20 watt through 100 watt VMS medical ac-dc family is available in a range of output voltages from 3.3 Vdc up to 48 Vdc. The models are compact, with the VMS-20 series measuring 2.38 x 1.6 x 0.67 in. To comply with the IEC 60601-1 standard, all models provide a typical leakage current less than 100uA, well below the limit of 500uA mandated by the standard.

Series Power (w) Output Voltages (Vdc) Size (in) Leakage Current
VMS-20 20 3.3, 5, 9, 12, 15, 24 2.38 x 1.6 x 0.67 <100uA
VMS-40 40 3.3, 5, 9, 12, 15, 24, 30, 36, 48 3.0 x 2.0 x 0.75 <100uA
VMS-60 60 5, 12, 15, 24, 48 4.0 x 2.0 x 1.1 <100uA
VMS-81 80 5, 7, 9, 12, 15, 18, 24, 30, 36 5.0 x 3.0 x 1.11 <100uA
VMS-100 100 5, 9, 12, 15, 18, 24, 28, 36, 48 5.0 x 3.0 x 1.05 <300uA



VMS High Density Medical Power Series


The VMS-160 series is a 160 W single output power supply in an industry standard 2 inch by 4 inch footprint. With a height of 1.08 inches, the series offers a power density of 18 W/in3. The VMS-365 series is a 365 W single output power supply in an industry standard 3 inch by 5 inch footprint. With a height of 1.17 inches, the series offers an even greater power density than the VMS-160 series, coming in at 19 W/in3. Both models provide leakage currents less than 300 uA, also coming in well below the 500uA specified by the IEC 60601-1 standard.

Series Power (w) Output Voltages (Vdc) Size (in) Leakage Current
VMS-160 160 5, 12, 24, 48 4.0 x 2.0 x 1.08 <300uA
VMS-300 300 5, 12, 15, 24, 36, 48 5 x 3.2 x 1.5 <300uA
VMS-300-CF 300 5, 12, 15, 24, 36, 48 5 x 3.2 x 2 <300uA
VMS-300-CFS 300 5, 12, 15, 24, 36, 48 6.5 x 3.2 x 1.6 <300uA
VMS-365 365 12, 24, 48 5.0 x 3.0 x 1.17 <300uA

Summary

CUI has developed a line of medical power supplies that offer class leading power density and energy efficiency. Carrying 60601-1 3rd edition medical safety approvals, these power supplies excel at delivering power in an extremely compact package, making them ideal for diagnostic, home healthcare, and dental applications where space is limited and minimizing energy consumption is a priority. For more information, please visit our website.


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