Usage:
Grounding The Frame
In any generator set installation, the frame of the generator must be positively connected to an earth ground or to the hull of the vessel. This connection is the first one that is made at the installation. This connection is the last one that should be removed. If the generator set is on flexible or resilient pads, the ground connection must be flexible in order to avoid possible breakage in later operation.
Ground connection cable or straps should have at least the current carrying capacity of the largest line lead to the connected load. Joints in cables or strap must be clean, free of electrical resistance, and protected from possible oxidation. Bolted ground connection joints eventually oxidize. The joints are frequent sources of radio frequency interference (RFI). Silver soldered and bolted joints are electrically and mechanically sound.
Neutral Connections
The generators with Wye configuration usually have the neutral ground when the generator is installed. However, there are some cases when definite measures which can be taken in order to prevent grounds on the load side. The purpose of the grounding of the neutral is to prevent load side equipment damage. If the neutral wire is grounded and one of the phase leads become grounded, the excessive current will open a load circuit breaker. The excessive current will also collapse the generator voltage. The result depends on the particular generator electrical characteristics, type of fault, and trip rating of the circuit breaker. An undervoltage device may be required in order to provide an adequate short circuit protection. There are some instances in which it is undersizable to ground the neutral wire. An ungrounded generator neutral lead is acceptable in the applications in which definite measures have been taken in order to prevent grounds to the phase leads.
Voltage Connections
The four voltage connections that are available are shown in (A) the Electrical Connections drawing 213-5334. The terminals must also be connected securely. The terminals must be insulated with a good quality electrical tape. If a Delta configuration is being used, a two-thirds winding pitch is recommended. If the generator pitch is not two-thirds, third harmonics will cause a high circulation current. This current can damage the wiring and cause a fire hazard.
Connections to the AVR (R438) will change according to the voltage configuration chosen and is shown in (B) the AVC Connections drawing 213-7425.
