York SSS 14L-B, Руководство по эксплуатации

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JOHNSON CONTROLS
37
SECTION 8 – MAINTENANCE AND TROUBLESHOOTING
FORM 160.00-O2
ISSUE DATE: 04/30/2019
8
VERIFY REAL PHASE CURRENT
IMBALANCE
The starter cabinet contains high voltages
that can cause injury or loss of life. Ex-
treme care should be taken when working
on this equipment.
Use this section to determine if the current imbalance
is real or a reporting problem.
1. Start the chiller.
2. Connect another current measuring device around
the output wire to the motor.
3. Compare the measured three phase currents to
each other.
4. If the currents are imbalanced, then continue. If
they are not imbalanced, continue to section titled
“Verify False Phase Current Imbalance”.
5. While the starter is running, record the three
phases of input voltage.
6. Add the 3 values of voltage together, and divide
by 3 to get the average voltage. Then take each
measured value, subtract the average value, and
divide this difference by the average value, and
multiply by 100. The result is the percentage
phase imbalance for that phase. Depending on the
load of the motor a value of 1.5% can cause a cur-
rent imbalance of 15%. If this is not the source of
the problem continue.
Example:
Phase A 480, Phase B 475, Phase C 482.
480 + 475 + 482 = 1437 / 3 = 479 avg.
475 – 479 = –4 / 479 x 100 = -0.8%
• Referring to the chart below, the current im-
balance due to the voltage imbalance is 7.5
% at 60% load
• A typical motor of today may induce a cur-
rent imbalance of up to 6%, but factory spec-
ifications allow for up to 8% before rejecting
a motor. So, if the measured current imbal-
ance is 13.5% or less, this is normal for the
above example, and no more investigation is
required. If this is not the source of the prob-
lem, continue.
Typical input voltage imbalance is 1 to 1½%. Ex-
cessive input voltage imbalance is 2% or greater.
Most often imbalances are due to unequal distribu-
tion of single phase loads within the building.
7. Connect an AC voltage meter from L-1 to T-1.
FIGURE 8 - CURRENT IMBALANCE DUE TO VOLTAGE IMBALANCE
30
25
20
15
10
5
0
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
% CURRENT IMBALANCE
% VOLTAGE IMBALANCE
NO LOAD
20% LOAD
40% LOAD
60% LOAD
80% LOAD
FULL LOAD
LD05247