EOS Power-Open Frame Medically Approved AC/DC Switch Mode Power Supplies

Frequently Asked Question

Q1. How to increase the reliability of power supply in end system?

Ans:

To increase the reliability of power supply, operating ambient temperature inside the end system enclosure should be maintained between 25 to 35degC. Select power supply which has 20% more power than actual need. For example, if the system needs a 200W it is suggested to select power supply rated for 240W output power or more. Reducing operating ambient and selecting higher rated power supply will increase the reliability of the power supply in end system. User need to ensure that temperature of critical part is well within its safe operating limit under worst operating conditions.

Q2. For multiple output why it is necessary to have min. load?

Ans:

For multiple output power supply, outputs need some min. load so that output voltage remains within regulation band. Output voltage regulation for multiple output is achieved by sensing the voltage of main output (one output only) which is rated for high power. For some of the single output power supply, min. load is required for proper start-up.

Q3. Why it is necessary to define load current value and time duration for the power supply with motors, light bulbs or capacitive loads?

Ans:

The motors, bulb and capacitive load draw very high surge/peak current during turn-on. Normal power supply is not rated and tested to meet high surge/peak current requirement. Therefore it is necessary to define the surge/peak current value along with time duration and repetitive rates. Accordingly proper rated power supply can be proposed to meet the requirement.

Q4. How to select a suitable proper circuit breaker or fuse for EOS power supply?

Ans:

The power supply draws high surge/peak current of approx. 35A to 70A during input AC supply application which will last for approx. 30 to 40milliseconds. Every breaker or fuse will actually have its surge/peak current rating. Users can choose a breaker or fuse which has a rated current just over input current of power supply and check whether the surge/peak current of the breaker or fuse can withstand the high inrush current of the power supply.

Q5. How to measure ripple and noise of power supply output?

Ans:

Ripple and noise of power supply output should be measured on oscilloscope. Oscilloscope to be set with AC coupling and 20 MHz bandwidth. Oscilloscope probe should have short leads of “input” and “ground” terminal at the tip of probe. The probe should be connected across the output terminal of power supply using 10uf Tantalum capacitor parallel with 0.1uf ceramic capacitor of suitable voltage rating across power supply output with proper polarity. Long lead of probe tips, measurement at load end and without decoupling capacitor network; ripple and noise measurement will be incorrect. The unit of ripple and noise is Peak to Peak.

Q6. Can I touch the “Black color Metal part” of power supply?

Ans:

The “Black color metal part” is heat sink of power supply and is at some electrical potential and should not be touched during power-on conditions and immediately after turn-off as it may remain charged for some duration after turn-off.

Q7. Can we use two unit of VLT150 connected in parallel?

Ans:

(M)ULP SERIES