BALTIC R410A-IOM-0708-E Page 63
EXAMPLE
The unit used for this example is a BAH035NSM1M with Economiser and Electric Heater type H
It is fitted with a fan which curve is shown on page 26 and a 2.2kW motor.
- Motor rpm: 1430 rpm
- cos
= 0.81
- Voltage = 400V
- Current = 3.77A
P
mech fan
= V x I x 3 x cos x
mech motor
x
Transmission
= 400 x 3.77 x 3 x 0.81 x 0.76 x 0.9 = 1.45kW
The unit is also fitted with a transmission kit 7
- Fixed Fan pulley: 160mm
- Motor adjustable pulley type “8450” opened 4 turns from fully closed or measured distance between pulley end plates is
25.7mm: from table 2 it can be determined that the motor pulley has a diameter of 99.2mm
rpm
FAN
= rpm
MOTOR
x D
M
/ D
F
= 1430 x 99.2 / 160 = 886.6 rpm
Using the fan curve below the operating point can be located.
It can be determined that the fan is providing approximately 6300 m3/h with a total pressure P
TOT
= 530 Pa
The pressure losses in the unit are the sum of all
pressure drops across the different parts of a unit:
- Coil and filter (measured) = 104 Pa
- Inlet into the unit = 30 Pa
- Options = 23 Pa for economiser and 91 Pa for
electric heater H
P = 104 + 30 + 23 + 91 = 248 Pa
The dynamic pressure at 7200m
3
/h is given at the
bottom of the fan curve (page 26).
Pd = 81Pa
The external static pressure available is therefore
ESP = P
TOT
- Pd - P
INT
=580 - 110 - 248 = 201 Pa
Fig. 42
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