LV- 120 x 0.90 = 108
HV- 120 x 1.10 = 132
VUB- VUB = 5
MULT- From Table No. 1, MULT = 75 with 75:5 CTs
OC- Service Factor Amperage = 61.6
UC- FLA x 0.80 = 56.2 x 0.80 = 45.0
CUB- Manufacturer suggests 5
TC- TC = 010 (To program RD1 and RD2), then TC = J00
RD1- To protect the pump from rapid cycling and reduce the number of
starts per hour, RD1 = 10 (Display value) x 0.5 = 5 Minutes.
RD2- Since the motor is large it will cool off slowly, RD2 = 60 x 0.5 = 30
Minutes.
MA- MA = 64 (Displayed value) x 0.158 = 10.1 Seconds.
OCTD- OCTD = 10 (Displayed value) x 0.158 = 1.58 Seconds.
RD3- The well history shows that it will fully recover in 2 hours.
RD3 = 240 x 0.5 = 120 Minutes
#RU- In this application, we know that the well will eventually recharge
itself, #RU = A.
#RF- This well is known for sand to jam the impeller, therefore “oc”
should be included so that the pump will attempt to automatically
restart after an overloaded condition. History shows that 1 start
attempt usually clears the sand out of the impeller. #RF = oc1
UCTD- UCTD = 10
GF- Because it may take several days to get a new pump motor and
schedule for maintenance personnel to remove and replace the
pump motor, GF setting of 10% of full load amperage will give the
well owner enough time to prepare for pump replacement.
GF = 56.2A x 0.10 = 5.6
#2
- Motor To Be Protected: 3
∅
, 4160 Volt, 200 Hp air compressor with a full
load amperage rating of 27A and maximum service factor amps of 30. One
4160/120 potential transformer is used for control power. Voltage monitoring
and reverse phase protection is not implemented. Use the following
calculations and reasoning to determine the appropriate settings for this
application.
LV- 120 x .9 = 108
HV- 120 x 1.1 = 132
VUB- Since L3 is not connected, VUB = 999
MULT- From Table No. 1, MULT = 50 with 50:5 CTs
OC- Service Factor Amperage = 30
UC- FLA x 0.80 = 27A x 0.80 = 21
CUB- Standard NEMA motor = 5
TC- General purpose motor = 20
RD1- Since this compressor takes about 60 seconds to bleed off
excess pressure after a shutdown, setting RD1 = 002 will allow
the compressor to unload before being restarted.
RD2- Because the motor may be hot from running in an unbalance or
single phase condition, a motor cool down time of 10 minutes,
06/26/03
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