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| How do I determine which
pump to use? |
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The SD 75, used with a 3/4 Hp pump
on 1 1/2 Hp motor, provides the performance similar to the 1 1/2 Hp
standard curve in the same pump series. In other words, you will be
using a ¾ Hp pump to get the performance of the 1 ½
Hp curve in the same series….use the 1 ½ Hp curve when
choosing the proper ¾ Hp pump to use. |
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| Why use a 3/4 Hp pump
on a 1 1/2 Hp, 3-phase motor? |
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The SubDrive 75 will spin the pump
at a rate that will produce constant pressure without overloading
the motor or exceeding a maximum speed of 80 Hz (@ 4,800 rpm). This
means that the speed of the pump may exceed the conventional speed
of 3,450 rpm. As speed increases, head increases by the square of
speed (exponentially), so you get a lot of head performance with just
a small increase in speed. If a 1 ½ pump is used on the 1 ½
Hp 3-phase motor, the SubDrive 75 controller would never let the pump
speed up past 3,450 rpm, since a higher speed would overload the motor. |
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| Whose pump can I use? |
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Any 3/4 Hp pump that is in the same
pump series as the 1 ½ Hp pump appropriate for the desired
head and flow performance. |
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| Can I put other pump
ratings on SD 75 |
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It is possible to use a 1 Hp pump on
a 1 ½, 3-phase motor, but it is important to remember that
you will still get the performance of the 1 ½ Hp curve in that
series. Use of the 1 Hp pump is recommended only in flow ranges where
a 1 Hp pump is available but a ¾ Hp pump is not. |
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| What is the range of
operating speeds for the SubDrive 75? |
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Minimum = 1,800, Maximum = 4,800 rpm |
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| Can I repair the SubDrive
75 controller? |
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Currently, the only option for repair
of a faulty or damaged SubDrive 75 controller is replacement. |
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| What about lightning? |
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The SubDrive 75 is equipped with premium
surge protection. It is designed to withstand a voltage surge of 6,000
volts for 28 microseconds. MOVs (Metal Oxide Varistors) are used to
protect the SD75 input and output terminals from voltages above 1,200
volts. These are the same devices used in computer surge protectors,
and serve the same function in protecting the electronics from surges
experienced during thunderstorms. |
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| Can I install a faucet
at the wellhead? |
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Yes. The SubDrive 75 is air-cooled
and is therefore not dependent on uninterrupted water flow between
the wellhead and controller. |
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| What is Power Factor
Correction? |
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The SubDrive 75 has a power factor
correction feature to keep voltage and current constantly in phase
(power factor = 1). This minimizes amp draw on the input side, and
significantly improves voltage distortion on the input side. Power
Factor correction reduces heat stress on the main supply transformer
to the house, thus extending its life. This makes the utility company
happy and avoids the additional fees being considered in the future
for utility customers with poor power factor loading. |
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| Will a leak cause the
SubDrive 75 to run the pump continuously? |
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The size of the leak and the capacity
of the tank used will determine the run time of the pump. If we use
the smallest tank possible, it would require a leak of approximately
1 cup per minute to drive the pump continuously. Larger diameter tanks
would require a higher rate to cause continuous pumping. This, however,
is not specific to the SubDrive 75 alone. All variable speed drive
systems would react similarly. Additionally, power consumption in
this case would be very low due to the fact that the pump is turning
at minimum revolutions. Also, since the SD75 has a soft start (no
in-rush current), the motor is not stressed during starting as much
as it is in a conventional system. |
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| Can I expect energy savings,
and if so, how much? |
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Depends on application…In general,
you should get some energy savings if average daily flow is more than
approximately 3 to 5 gpm |
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| How does the unit hold
pressure (the dithering)? |
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The pressure switch tells the controller
to speed up the motor if the pressure is below the pressure setting
and to slow down the motor if the pressure is above the pressure setting.
IT IS NOT CONSTANTLY TURNING THE MOTOR ON AND OFF. The result is a
continuous ramping up and down around the pressure set point. This
"pressure dither" may or may not be visible at the gauge,
but is generally not noticeable at a faucet or tap. |
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| Life of pressure sensor? |
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Millions of cycles. This sensor is
rated for 500 psi. It is a heavy-duty sensor that carries less than
5 volts. It does not carry load, so there is no arcing and consequently
much less deterioration of the contact points compared to conventional
pressure switches. The range of motion of the contacts is very small
(millimeters), and there is no "snap action" invloved. The
result is a very durable sensor. |
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| Will the orifice of the
pressure sensor be clogged? |
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The orifice has been enlarged to a
maximum diameter and we don't expect to have obstruction problems
from particles or chemical build-up (calcification, iron deposits).
Since the orifice of the SubDrive 75 pressure sensor is larger than
most, if not all standard pressure switches, there is less chance
of obstruction compared to conventional systems. Although mounting
orientation is not usually a problem, you should not mount the sensor
in an inverted orientation (with black part down). This could allow
the orifice to collect debris and block the pressure sensing capability
of the sensor. |
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| Does the SubDrive 75
use the same enclosure as the FE medium control box? |
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No |
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| What breaker size should
I use? |
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It is possible to use a 15 or a 20
amp breaker with the SubDrive 75. |
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| Can I put SD 75 outside
or in direct sunlight? |
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SD 75 should be installed inside and
out of direct sunlight. Outside installations are possible if the
SubDrive 75 controller is protected from wind-driven rain and temperature
extremes, as long as the SubDrive and the surrounding area remain
well-ventilated (see Installation Manual, page 10). |
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| Can I use this as a generic
Variable Speed Drive? |
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At this time, SD 75 is not recommended
for application other than submersible pumps. |
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| What happens if I put
another submersible on it? (Motor other than FE) |
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The SubDrive 75 is designed to work
with a 1 ½ Hp, 230 Volt, 3-phase motor. If another type of
motor is used, it is very likely that the motor will never start.
Also, the fault indications and motor protection features may not
work properly. |
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| What size cable? |
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· Max: 390
ft of 12 AWG or 610 ft of 10 AWG (manual pg 11) |
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· lengths do
not correspond to AIM manual due to max resistance requirements for
fault detection |
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| Can I use the SubDrive
75 with generators? |
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The SubDrive 75 may not operate properly
with generators unless the following guidelines are followed:
The generator should be capable of supplying single-phase, 230Vac,
50Hz or 60Hz power, with a minimum continuous rating of 3,500 Watts.
(Refer to the generator installation guide for grounding and safety
considerations. The generator ground along with both L1 and L2 power
connections should be made to the SubDrive 75).
When using the SD75 as the only load it is recommended to add a parallel
lamp load of about 450Watts. This serves to improve the output regulation
of the generator. This can be implemented with two 225Watt, 125V lamps
(mounted in appropriate fixtures), connected in series. The series
connection of the lamps would then be connected across the 230Vac
source. (With the generator running, the intensity of the lamps should
remain constant indicating that the generator is maintaining constant
output regulation of the 230Vac line. If the lamp intensity fluctuates,
the generator is having difficulty maintaining output regulation and
it maybe necessary to reduce the water demand to lighten the load
from the generator.)
When considering multiple loads from a generator, the various types
of loads can be critical for their effect on output regulation. In
a case like this it would be best to contact the generator vendor
for further guidance. Likely recommendations would be to specify a
generator with a significantly higher power rating than the total
of the expected loads, and to include a parallel lamp load. |
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| Can I use the SubDrive
75 with a solar inverter? |
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No. |
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| Is this a special motor
for SD 75? |
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No. The motor to be used with the SubDrive
75 is a standard 3-phase, 230 V, 1 1/2 Hp (23451492XX) that is readily
available from pump suppliers. |
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| What is the highest ambient
temperature that the SubDrive 75 will withstand and still provide
full power? |
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The SubDrive 75 manual indicates that
"The CP Water SD75 controller is intended for indoor use and
for operation in ambient temperatures up to 104°F (40°C)".
This specification is based on an input line voltage to the SubDrive
75 of 190 Volts (RMS). We have done further testing to determine the
performance of the SubDrive 75 at higher ambient temperatures with
230 volt (RMS) input. The results of our testing indicate that the
SubDrive 75 should be able to provide full power in ambient temperatures
as high as 125°F (51.6°C). |
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| Can I mount this in a
damp environment? |
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The SubDrive 75 should not be mounted
where condensation can occur. |
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| Why does pressure fall
off when the all faucets are open? |
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In this case, it is possible that the
pump has reached its maximum performance for the flow demanded. At
this point, the performance will follow the curve as in the case of
a conventional pump (see graph below). |
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Another way that pressure at a particular
tap may drop is simply due to restriction in the plumbing. If a faucet
shares a branch with another tap, pressure at one may drop when the
other is opened simply because there is restriction to that branch.
Restriction increases with smaller pipe diameter, longer runs, or
more elbows and tees. If the gauge reading agrees with the pressure
setting but faucet pressure drops when another tap opens, the pressure
drop is due to restriction downstream of the sensor.
If there is distance between the gauge and the pressure sensor,
the pressure at the gauge can appear to rise and fall as flow varies.
This is due to restriction between the gauge and the sensor. As
flow increases, the difference between the pressures at the sensor
vs. the gauge will be greater. The best practice is first to mount
the pressure sensor as close to pressure tank as possible (with
minimum restriction), then mount the gauge close to the sensor. |
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| Does the SubDrive 75
go to S.F. amps or to F.L.A.? |
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The maximum amp draw (S.F. Load) on
a SubDrive 75 (motor lead from the controller to the motor) corresponds
to the S.F. amps listed in the AIM manual for the 3-phase, 230 volt,
1 ½ Hp motor (5.9 amps). |
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| What happens if the pressure
switch cable is cut? |
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The SubDrive 75 will shut off. |
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| Can I use SD75 in hot
water applications (140 degrees)? |
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FE recommends de-rating the motor in
hot water applications. Since the SD75 uses one motor type, this is
not an option at this time. |
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| Can I use a GFCI with
the SubDrive 75? |
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Due to the nature of the RFI filtering
process in the SubDrive 75, a GFCI will most likely be tripped on
start-up and the motor will not run. |
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| Can the motor run backward? |
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Yes. If the output leads to the motor
are connected incorrectly, the motor will run in reverse. The first
indication of this is typically a much lower production of water.
The solution is to switch any two of the output leads. |
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