Gradually decrease the frequency of the applied voltage until multimeter reads infinite ohm. Note
frequency at which relay trips.
(a) If 60 hertz (50 hertz) frequency relay trips as specified in step (3)(a), above, the 60 hertz (50
hertz) frequency relay is good. Disconnect test equipment and install 60 hertz (50 hertz) frequency
relay back in generator set.
(b) If 60 hertz (50 hertz) frequency relay does not trip as specified in step (3)(a), above, the 60 hertz
(50 hertz) frequency relay is defective and should be replaced. Install an adjusted replacement 60
hertz (50 hertz) frequency relay in the generator set.
Install. See Figure 5-9.
Relays K107 and K108 are identical items, but are adjusted to different trip points. Do not get
them reversed. Each relay must be adjusted for proper trip point prior to installation. K107
must be adjusted as the 60 Hz frequency relay; K108 as the 50 Hz frequency relay. Accidental
reversal of the relays may result in equipment damage.
Verify relay K107 (Kl08) has been properly adjusted for 60 Hz (50 Hz) operation.
Install relay K107 (59) or K108 (58) and secure it with screw and captive washer assembly (60).
Make wiring connections as necessary and discard wire tags.
5-33. REVERSE POWER RELAY K109 (61, Figure 5-9).
Inspect screw and captive washer assemblies (62) and electrical connectors for security.
Inspect wires connected to reverse power relay K109 for evidence of burning or insulation breakdown.
Remove. See Figure 5-9.
Tag and disconnect wires from relay terminals.
Remove reverse power relay K109 by removing screw and captive washer assemblies (62).
Preparation for bench test.
Remove reverse power relay K109 in accordance with step b, above.
Obtain single phase 120 V ac power source, 0-1 ampere AC ammeter, variable 0-10 V ac power
source, and a multimeter set to RX1 scale.
See Figure 5-28. Connect 120 V ac, single phase power source at terminals 3 and 4 of K109.
Connect the 0-1 ampere AC ammeter in series with a 0-10 V ac power source installed across
terminals 5 and 6 of K109. Connect multimeter set to RX1 scale across the terminals marked NC
(normally closed) on the relay.
Turn on 120 V ac, single phase power source and 0-10 V ac power source set to zero volts. Observe
multimeter indication. Reading should be zero ohm.
From zero setting, increase 0-10 V ac source input into terminals 5 and 6 of K109 while monitoring
current reading on the ammeter.