Hussmann Ingersoll Rand, User Manual

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Electrical Data 2
Method Used to Determine Rated-Load Current
Model Type P S Q T
Application
Temperature
HT MT LT HT MT LT LT only LT only
Refrigerant
R-22
R-404A
R-507a
R-22
R-404A
R-507a
R-22
R-404A
R-507a
R-22
R-404A
R-507a
R-22 R-22
NEC Method
Used
440.52
(A)(2)
440.52
(A)(3)
440.52
(A)(2)
440.52
(A)(3)
440.52
(A)(2)
440.52
(A)(2)
.
440.52 (A)(2) A thermal protector integral with the motor-compressor, approved for use with the motor-compressor
that it protects on the basis that it will prevent dangerous overheating of the motor-compressor due to overload and
failure to start. If the current interrupting device is separate from the motor-compressor and its control circuit is
operated by a protective device integral to the motor-compressor, it shall be arranged so that the opening of the
control circuit will result in interruption of current to the motor-compressor.
440.52 (A)(3) A fuse or inverse time circuit breaker responsive to motor current, which shall also be permitted to
serve as the branch-circuit short-circuit and ground-fault protective device. This device shall be rated at not more
than 125 percent of the motor-compressor rated load current. It shall have sufficient time delay to permit the motor-
compressor to start and accelerate its load. The equipment of the motor-compressor shall be marked with this
maximum branch-circuit fuse or inverse time circuit breaker rating.
Notes: 1. The above standard is also written in UL 1995 Section 23.11 (B) & (C).
2. All IR Impact
™
compressors employ the use of an internal thermal protector.
The following pages list MCC and RLA values for each compressor under the three different rating
conditions; High Temperature (greater than 32 to 53.5
°
F), Medium Temperature (greater than -10
°
F
and less than or equal to +32
°
F), and Low Temperature (less than +10
°
F and greater than -40
°
F). From
these values, the breaker, contactor, and wire size are determined. The parameters for this test are
established in ARI 540
Positive Displacement Refrigerant Compressors and Compressor Units and UL
984 Refrigerant Compressors and Compressor Units .
Component Sizing
The sizing of the circuit breakers using 440.52(A) (2) for compressors and all voltages are based on the
value for rated-load current and are sized to insure that the breaker will trip before the motor overheats.
The circuit breaker must be sized at minimum of 125 percent to a maximum 225 percent of RLC, with a
minimum circuit breaker size of 15 Amperes. The sizing of the circuit breakers using 440.52(A) (3) for
compressors and voltages are based on the value for rated-load current multiplied by 125% and choosing
the next smaller circuit breaker.
The contactor is sized using specifications as set by Underwriters Laboratories and the National
Electrical Code Section 430 Table 151(B) in conjunction with Table 430.150.
Contactor ratings must be 100 percent or greater of the rated-load current and equal to or the next size
larger than the current value found in the Tables using the locked rotor current for each motor-
compressor. Minimum contactor size is 20 Ampere.