Spec Sheet

Page 8
Air Conditioner
(Tons)
Anaheim
Electric
240V
Maui Electric Company
PG&E
240V
Vancouver
Electric
240V
Scroll Compressor
Manufacturer
208V 240V Copeland Danfoss
1 & Less 36 60 100 - 48 - -
1.5 48 60 100 - - 48 -
2 60 60 100 60 60 73 -
3 80 60 100 80 80 109 115
4 -----134150
5 120 60 100 120 120 158 145
7.5 170 60 100 170 - 185 145
10 220 60 100 - 220 - -
Utility Regulation on Motor Starting Current
Increasing Utility Regulation
Most of the problems discussed so far relate specifi cally
to the homeowner. However, power distribution
companies experience issues when it comes to in-
rush current. Depending on whether the utility is
dealing with an existing network or working on plans
for a network expansion, additional investment and
operational costs could be required. As more homes
get retrofi tted or built with air conditioning it will
require utilities to boost distribution equipment sizing
such as transformers and conductors accordingly. This
additional cost is driven higher since they must size the
equipment for worst case scenario. As stated previously,
in-rush current is 5-8 times greater than operating
current; therefore, in-rush current is a signifi cant
parameter to the power distribution company. Even if
the time period is very fast they still must overcome the
instantaneous demand of the in-rush current. Currently,
the in-rush current regulations in the US are lenient.
As energy costs continue to rise, it is only a matter of
time before limits are established for in-rush. The table
below illustrates some of the limits that have started
to emerge from utility companies on the West Coast.
The in-rush current listed in the table is a standard air
conditioning scroll compressor that would be used in a
residential application.
Other countries such as the United Kingdom, Ireland,
Germany, and Australia have already implemented
regulations that limit the inrush current that can be
installed on a residence. This is often referred to as the
“45 Amp Rule” where the in-rush current is limited to
45 A. If adopted in the US, it would limit most homes
to 1.5 ton air conditioning system. Most homes in the
US are larger than homes in European countries and
generally require a minimum of 2-3 tons of capacity.
Larger homes can require up to 4-5 tons which is
almost 3 times the European limit. However, when a
SureStart is installed it reduces those values by 70%. A
compressor with 158 Amp in-rush will be reduced to 47
A. Since the US power supply and distribution network
was designed differently from other countries, it is
likely these limits, if established, will be slightly higher
than the 45 A European model and unique for North
American countries.
Off-Grid & Generators
SureStart offers an ideal solution for homeowners or
industrial solutions looking to use their HVAC units on
off-grid power or unstable power supply conditions.
This is especially applicable for situations in remote
locations where power is limited or where long cable
layouts are required, or necessitate use of generator or
solar based service.
Without a softstart or even installations incorporating a
hard start kit, one would have to ensure that generator
or inverter surge capacity is sized to at least 5 times
motor rating. Higher effi ciency compressor motors can
even demand 6-7 times its nominal kW rating at start.
This is to ensure that the motor does not stall during
each start. The excess surge due to in-rush current can
easily lead to brown outs, light fl icker and even cause
other equipment in same circuit to trip. The obvious
consequence is the need to oversize the local generator
and inverters to avoid this issue. SureStart can reduce
the cost of going off-grid by reducing the generator size.
SureStart easily overcomes this by reducing the peak
surge demand at start. In single phase, it is suffi cient
enough to size the generator surge requirements to
roughly 2.5 times the kW rating of the motor. For three
phase applications, it is recommended to size the
generator surge requirements to 4 times the kW rating
of the motor.