Generac — Testing Under Load
Testing & diagnosis · Generator AC output
From a Generac service manual covering: NP-50G, NP-50LP, NP-66G/LP, Q-40G, Q-55G/LP, Q-70G/LP. Check it applies to your exact model before use.
Applies to: Generac NP-50G, Generac NP-50LP, Generac Q-40G, Generac NP-50G/LP engine
Procedure
- Apply electrical loads equal to about 75-100% of unit's rated wattage/amperage capacity.
- Check frequency with electrical load applied; frequency should not drop below about 58 Hz under load.
- Let unit run at least 30 minutes with load applied; check unit is not running excessively hot and adequate cooling air flow is available.
- Do not allow unit to overheat during prolonged operation.
Tools required
- AC frequency meter Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- 58 Hz minimum under load
Full service-parts list: Generac NP-50G →, Generac NP-50LP →, Generac Q-40G →
Source: Generac service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.