SNOWPURE, LLC, 2005-2018
VERSION 3.5 (XL+EXL)
–FEBRUARY 2018
PAGE 21
Environmental Conditions
The following are environmental conditions the OEM should consider during system
design and installation:
For Indoor Use Only
– Do not expose to direct weather or environmental conditions.
Temperature: 5ºC - 45ºC
Maximum Relative Humidity (RH) : 80% up to 45ºC
Pollution Degree for Electrical Components: 3 or better
Ingress Protection rating: IP34.
Cost of Power for the EDI Module
A typical XL-500-R module operating at 300VDC and drawing 2 amps will cost under
$1.00 per 8-hour period. This assumes that the power supply is 85% efficient and the
local utility charges $0.12 per kW-hr. See Appendix #7 for the power and cost
calculations.
DC Power Supply Requirements
The power supply should be a regulated DC power supply with enough power to cover
typical and extreme operating conditions.
SnowPure recommends setting the voltage (driving force) and allowing the current to
float (follow the RO permeate conductivity as it changes).
Voltage output should be controllable. The voltage range should include the
regeneration conditions. The power supply should have current-limiting capability to
protect itself and the EDI module(s). Each module may be separately fused.
Current depends on the conductivity of the EDI feed and the concentrate flow. There
should be excess current capability designed in to cover higher currents in case module
regeneration is needed, or if RO permeate conductivity increases with system age.
For protection the system must have an automatic interlock to turn the power OFF in
case of NO WATER FLOW. It may be controllable from a remote source such as a PLC
or the system control computer. The interlocks may be a combination of logic, flow, and
pressure switches. The power supply may have internal diagnostics and an alarm relay
output.
AC noise (ripple) can be up to 5%. AC low- and high-frequency ripple may affect the
readings of local electronic instruments, such as conductivity or resistivity meters.
Power supply should conform to UL, CSA, or CE requirements as local code requires.
Local code may require features such as power factor correction (PFC) and EMI
shielding. If NEMA rating is required, the NEMA enclosure must have enough heat
removal to keep the power supply cool. Typical power supply efficiency is 85-90%, so
AC input power will be about 10-15% higher than the rated power of the supply.