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Putian ChinaHanji Power Limited,Co main tech data for diesel engine#4JB1 | ||||

Model Ser. | 4JB1 Nature inspiration engine |
4JB1 supercharged engine |
4JB1 supercharged /O2 engine |
4JB1 Turbo-charged Center cold Altogether axle engine |

Inlet Method | Nature inspiration | supercharged | supercharged/OII | Turbo-charged Center cold Altogether axle |

Diesel Engine Model | oil-cooled,four-stroke, in-line,valve in-head | oil-cooled,four-stroke, in-line,valve in-head | oil-cooled,four-stroke, in-line,valve in-head | oil-cooled,four-stroke,in-line,supercharged,center Leng,common-railed |

Number of Cylinders | 4 | 4 | 4 | 4 |

Bore and Stroke | 93×102 | 93×102 | 93×102 | 93×102 |

shape size(L*W*H)mm | 734×612×682 | 742×634×718 | 742×634×718 | 742×634×718 |

New Weight(kg) | 224 | 230 | 230 | 250 |

Exhaust Volume (cc) | 2.771 | 2.771 | 2.771 | 2.771 |

compression ratio | 18.2 | 18.2 | 18.2 | 17.2 |

fuel supply mode | direct injection | direct injection | direct injection | direct injection |

Lubrication Method | The forced circulation splashes duplicate is suitable | The forced circulation splashes duplicate is suitable | The forced circulation splashes duplicate is suitable | The forced circulation splashes duplicate is suitable |

Cooling Method | sealed pressed circulation | sealed pressed circulation | sealed pressed circulation | sealed pressed circulation |

Starting Method | electric | electric | electric | electric |

EG stop mode | fuel control systme | fuel control systme | fuel control systme | fuel control systme |

output power/speed(kW/r/min) | 57/3600 | 68/3600 | 68/3600 | 85/3600 |

Maximum Torque(N·m/r/min) | 172/2000 | 210/2100 | 210/2100 | 285/2100 |

idle speed(r/min) | 750±50 | 750±50 | 750±50 | 750±50 |

maximum no load governed speed(r/min) | 4200 | 4200 | 4200 | 4200 |

Min fuel comsumption on Full load(g/kW·h) | 224 | 230 | 230 | 250 |

Temperature of cold start | -25 ℃ | -25 ℃ | -25 ℃ | -25 ℃ |

Temperature of exhaust | <600 ℃ | <600 ℃ | <600 ℃ | <600 ℃ |

noise Db(A) | ≤ 106 | ≤ 106 | ≤ 106 | ≤ 100 |

Short circuit interrupting ratings of the Low Voltage Generator

Circuit Breakers.

Low voltage circuit breakers are rated on symmetrical basis. Therefore the interrupting

ratings (or interrupting capacity) of the low voltage circuit breakers, published by

manufacturers, are expressed in RMS symmetrical current.

The instantaneous function of the circuit breaker trip unit is designed to react to the

peak value of the phase current. Since circuit breakers are capable of parting their

main contacts during first 1-3 cycles of the fault, their short circuit ratings should be

higher than the maximum available symmetrical fault current during the 1st cycle of a

fault.

Generator direct axis subtransient reactance (X"d) is the reactance of the stator winding

at the instance of fault. RMS symmetrical values of the fault current at the generator

terminals can be calculated as follows:

Three phase fault:

X d

Isc E

3 "

=

Line to Neutral fault:

2 0 "

3

X d X X

Isc E

+ +

=

Where:

E – generator line to line voltage before fault, Volts

X”d -- generator direct axis subtransient reactance, Ohms

X2 -- generator negative sequence reactance, Ohms

X0 -- generator zero sequence reactance, Ohms

Note: all reactance values should be used as the “worst case values”. Example: if X”d

value is specified by the generator as 20% +/- 15%, that the “worst case value” of X”d

should be calculated as 20%* 0.85 = 17%.

Typical values for a 2.25 MW, 480 V generator are: X”d= 0.013 Ohms (15.9%), X2=

0.012 Ohms (14.6%), X0= 0.003 Ohms (3.7%).

As can be seen if the generator neutral is solidly grounded, the ground fault current will

exceed the value of the three phase fault current.

Let’s assume that two (2) of the above generators are operated in parallel with high

impedance grounded neutral. In this case, three phase bolted fault will produce the

highest fault current, since line to ground fault will be limited by the neutral grounding

resistor(s). Than the highest fault current they can produce is approximately 42,615

Amperes of RMS symmetrical current. For the “worst case scenario” we will assume

Copyright © 2006 Advanced Power Technologies, Inc.

www.aptinc.net

2

close proximity of the switchgear to the generator sets and therefore ignore the values

of X and R of the connecting cables as negligible. In this case, as a rule of thumb, if the

80% of nameplate interrupting capacity of the feeder circuit breakers connected to this

generator bus is above 42.615 kA, no further calculations are generally required.

If the 80% of nameplate interrupting capacity of the feeder circuit breakers connected to

this generator bus is not above 42.615 kA, than further evaluation is required as

outlined below.

1. Type of low voltage circuit breaker. Most low voltage circuit breaker used in

North American power systems are rated to ether ANSI C37 standards or UL

489. ANSI rated circuit breakers are tested at 15% Power Factor (P.F.) UL 489

rated breakers are tested at 20% Power Factor.

2. Calculate short circuit Power Factor or Power System X/R ratio. System Power

Factor and X/R ratio are both indicators of the mathematical relationship between

system reactance and resistance. They are related by the following

formula: P.F . = cos(tan −1 ( X / R )) . For example 15% Power Factor

corresponds to 6.59 X/R ratio and 20% Power Factor corresponds to 4.9 X/R

ratio. If actual system fault X/R ratio higher than the X/R ratio the circuit breaker

was tested to, than the fault interrupting rating of the circuit breaker needs to be

adjusted by applying a derating multiplier further called “Derating Factor”. To

determine required interrupting rating of the circuit breaker, value of the available

fault current needs to be multiplied by a “Isc Multiplying Factor” as outlined in

Table 1.

The reason the system X/R ratio needs to be considered is that the actual generator

fault current is not symmetrical. It consists from the symmetrical AC component and a

DC component sometimes called DC offset. A typical asymmetrical current wave is

shown in Figure 1. The actual degree of asymmetry and therefore the actual magnitude

of current the circuit breaker will need to interrupt, depends on the system X/R ratio and

when in the power cycle the fault occurs. The higher the system X/R ratio, the greater

the potential for the instantaneous peak value of the fault current to reach its maximum

theoretical instantaneous peak value. The initially asymmetrical fault current becomes

symmetrical as the DC component of the fault current decays.

Copyright © 2006 Advanced Power Technologies, Inc.

www.aptinc.net

3

Figure 1

For a typical 2.25 MW, 480 V generator system described above the “worst case” X/R =

0.013/0.0015, which corresponds to an X/R ratio of 8.67 or system Power Factor of

approximately 11%.

The Table 1 below can be used to determine the required derating of the circuit

breakers interrupting ratings. In our example the required feeder circuit breaker

interrupting ratings will be:

1. For an ANSI rated circuit breakers: 42.615 kA * 1.049 = 44.7 kA

2. For a UL 489 rated circuit breakers: 42.615 kA *1.11 = 47.3 kA

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