Engineered air EngA CU Series, Инструкция по установке, эксплуатации и обслуживанию

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A
CU MANUAL
IOM-14 31 of 46 Feb 06 R4
phase to phase voltage imbalance should be less than 2%. A 2% voltage imbalance can cause up to
a 10% current imbalance that will overheat motor windings.
To calculate voltage imbalance (NEMA method) refer to the following example:
Phase to phase voltage readings: 235V 236V 230V
The average Voltage between legs is 233.7V (235+236+230)/3
Highest voltage deviation from average is: 233.7V – 230V = 3.7V
Voltage imbalance percentage = Highest deviation divided by average X 100
3.7 / 233.7 x 100 = 1.6% This imbalance is less than 2% and therefore is OK
If voltage imbalance is greater than two percent (2%), turn off main disconnect and contact the
installing electrical contractor to have the voltage condition corrected.
16.
Confirm field wiring voltage drop is less than 10% when equipment is operating.
17.
For the unit to operate properly a system air balance must be performed to ensure correct air flow.
Failure to do so can damage the equipment and/or building and can be a cause of poor indoor air
quality.
18.
Damper sections:
a) Flat mixing dampers:
Both the fresh air and return air dampers are fully open when the dampers are at a 45° angle when
fully stroked. This provides optimum mixing of the air streams for this damper arrangement.
b)
Angle mixing damper:
Angle mixing section dampers open to an angle of 90° when fully stroked. This provides optimum
mixing of the air streams for this damper arrangement.
19.
Some units are equipped with an adjustable coil air bypass. This must be field adjusted during the
system air balance to ensure proper air flow across the coil. Adjust the bypass to achieve coil
pressure drop as stated on the submittal and/or the unit function sheet.
20.
Allow system to operate until stable running conditions have been established.
21.
Check and record amperage draw of each motor and compressor. Refer to unit label for running
full load amps of motors and compressors.
22.
Measure and record the suction and discharge pressures. On compressors equipped with an oil
pump, measure and record net oil pressure. (net oil pressure is oil pressure minus suction
pressure.).
Check and record the oil level on compressors that are equipped with oil level sight glasses.