P and N regulation – What’s the difference?

Why do Balmar sell alternators and regulators that are designed to work from the ‘P’ side and not the ‘N’?

When regulating or controlling the output of an alternator, the regulator can be designed to work on either the Positive (P-Type) or Negative (N-Type) side of the alternator.

With an N-Type sytem, if the field wire shorts to ground, or if the alternator internally shorts to ground, the alternator will immediately produce full output — both current and voltage.

This output will continue regardless of the battery’s state of charge or the temperature of the alternator. The result can be extreme overcharging of the battery and potential explosion. Overheating and subsequent damage to the alternator can present a fire hazard. It is for these reasons that all Balmar alternators are designed for P-Type regulation.

If the field wire shorts to ground or the alternator develops an internal short, the included fuse on the field wire simply blows and the alternator stops all output.

Most automotive or other internally regulated alternators are N-Type. When converting these units to be used with a Balmar external regulator, the alternator must also be converted to P-Type for safety and compatibility with Balmar regulators.   The difference between P-Type and N-Type alternator circuits is shown below: