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Diesel Generator Operation Manual SYSTEM OPERATION Operation Part 2
Operating Recommendations&Generator Set Operation
Drain and replace the crankcase oil after the first hours of operation on new generator sets. Refer to the Maintenance section of this manual for the recommended procedures.
4.2 No Load Operation
Periods of off-load operation should be held to a minimum. If it is necessary to keep the engine running for long periods of time when no electric output is required, best engine performance will be obtained by connecting a load of at least 30% rated load, but not to exceed rated load. Such a load could consist of heater element or load bank.
4.3 Exercise Period
Generator sets on continuous standby must be able to go from a cold start to being fully operational in a matter of seconds. This can impose a severe burden on engine parts.
Regular exercising keeps engine parts lubricated, prevents oxidation of electrical contacts, and in general helps provide reliable engine starting.
Exercise the generator set at least once a week, for a minimum of 30 minutes with load, so the engine reaches normal operating temperatures.
4.4 Low Operating Temperatures
Use a coolant heater if a separate source of power is available. The optional heater available from Cummins will help provide reliable starting under adverse weather conditions. Be sure the voltage of the separate power source is correct for the heater element rating.
4.5 High Operating Temperatures
Refer to the generator set nameplate for the maximum ambient operating temperature, if applicable.
4.6 Operating Conditions for Prime, Standby and Continuous Power Ratings.
Note: All generator sets supplied by the Company must be run under the following operating conditions.
4.6.1 Continuous Power rating (COP) for constant load applications
The Continuous Power Rating is applicable to utility parallel and other non-variable load applications for supplying power continuously to a load of up to 100% of the continuous rating for an unlimited number of hours per year between the stated maintenance intervals and under stated ambient conditions. All maintenance must be carried out as prescribed in The Company Manuals. No sustained overload capability is available at this rating. This rating is applicable for utility base load operation. In these applications, generator sets are operated in parallel with a utility source and run under constant loads for extended periods of time.
4.6.2 Prime Power Rating
The Prime Power Rating is the maximum power available during a variable load sequence which may be run for an unlimited number of hours per year, between the stated maintenance intervals and under the stated ambient conditions. All maintenance must be carried out as prescribed in The Company Manuals. Prime Power applications fall into one of the following categories:
a)Unlimited Time Prime Power (for variable load applications)
Prime power is available for an unlimited number of annual operating hours in variable load applications. The permissible average power output under variable load shall not exceed a 70% average of the prime power rating during any operation of 2 hours. The total operating time at 100% prime power shall not exceed 0 hours per year. A 10% overload capability is available for a period of one hour within a twelve hour period of operation, in accordance with ISO 3046-1. Total operating time at the 10% overload power shall not exceed 2hours per year.
b)Limited Running Time Prime Power (for constant load applications)
Prime power is available for a limited number of hours in a non-variable load application. It is intended for use in situations where power outages are contracted, such as utility power curtailment. Generators may be operated in parallel with the public utility up to 7 hours per year at power levels never to exceed the prime power rating. No sustained overload capability is available at this rating. The Customer should be aware, however, that the life of any generator set will be reduced by constant high load operation. Any operation exceeding 7 hours per year at the prime power rating should use the Continuous Power Rating.
4.6.3 Standby power rating (for variable load applications)
The Standby Power Rating is applicable for supplying emergency power for the duration of a utility power interruption, between the stated maintenance intervals and under the stated ambient conditions. All maintenance must be carried out a prescribed in The Company Manuals. No overload capability is available for this rating and utility parallel operation is not permitted at the standby power rating. For applications requiring sustained utility parallel operation the limited time prime power rating or continuous power rating must be utilised as applicable.
This rating is applicable to installations served by a reliable normal utility source. Generators should be sized for a maximum average load factor of 80% of the standby power rating with a maximum of 200 hours of operation per year, which includes less than 2hours per year at the standby power rating. In installations served by unreliable utility sources (where outages last longer, or occur more frequently), where operation is likely to exceed 200 hours per year, the Prime Power rating should be applied. The Standby Power rating is only applicable for emergency and standby applications where the generator set serves as the back-up to the normal utility source. Negotiated power outages are not considered as emergencies.
4.6.4 Notes applicable to all ratings
The following notes are applicable to all ratings, unless otherwise agreed by the Regional Sales Manager of the Company in writing:
1.When determining the actual average power of a variable power sequence in any of the ratings above, power of less than 30% of the emergency standby power shall be taken as 30% and the time at standstill shall not be counted.
2.Variable load is calculated in accordance with methods and formulae given in ISO 85- 1:1993.
3.All 3-phase generators are rated for 0.8 power factor lag. Single-phase generators are rated for 1.0 power factor.
4.All ratings are based on the following reference conditions:
a)Ambient temperature – 27oC (81oF)
b)Altitude above sea level – 15metres (492 feet)
c)Relative humidity – 60%
d)Output Power may be subjected to de-rate if the above conditions are exceeded.
5. If any of the above conditions are not satisfied, the operational life of the generator set may be reduced.
6.Short term parallel operation with the utility, for load transfer purposes only, is permitted with all ratings.
4.7 De-Rating Factors
For de-rating factors applicable at specific sites, please contact your authorised distributor.
5.1Sequence of Operation
The generator set is run Automatically using a Remote Start signal, or Manually using the switch panel controls. Generator set indications are provided on the control panels. If a fault is sensed at Start-up, the engine is locked out and will not start.
When the PCC 3201 is put in the Manual mode and the Manual Run button is pressed, the generator set performs an automatically sequenced manual start. First, the PCC 3201 initiates a starter cranking signal and verifies that the engine is rotating. Then it provides sufficient fuel for the engine to accelerate up to start-disconnect speed.
After the initial start procedure, the control system ramps the generator set to rated speed and voltage. The Ready to Load output is activated when the AC voltage and frequency exceeds 90% of nominal.