Woodward EGCP-2 - Page 92

EGCP-2 Engine Generator Control Package Manual 26174
82 Woodward
Speed/Frequency Mismatch Alarm
 Compares engine speed (MPU) to generator frequency (PT signal) and
alarms on a difference.
 Used to indicate loss of MPU, or Loss of Generator Field Voltage.
 If Start Sequencing is Disabled and no MPU is present, then this alarm
compares Generator Frequency to Generator Frequency, so the Speed/
Frequency Mismatch Alarm will never alarm.
Woodward recommends that the Speed/Frequency Mismatch Alarm be
set the same as the Overspeed Alarm to protect against the loss of the
MPU signal.
Overcurrent Level
 Range 5.0 – 30,000 A
 Overcurrent level setting must be a greater value than the rated current of
the generator
 Set for per Phase Overcurrent
3 Phase sensing, selects phase with highest current
 Uses Inverse Time Function as basis for overcurrent detection
The overcurrent is based on AMP
SECONDS.
AMP
SECONDS are determined by:
Overcurrent Delay x (Overcurrent Level – Rated Current)
 Per Phase Rated Current is determined by the Configuration menu
Voltage Input—Wye or Delta
Rated kVA
Voltage Ref
Per Phase Rated Current equals
WYE voltage input: (Rated kVA / Voltage Ref) / 3
DELTA voltage input: (Rated kVA / Voltage Ref) / 1.732
Example 1: 480 V L-L system, 277 V L-N system
110 kW Generator, 4:1 PT Ratio
Voltage Input = Delta Voltage Input = Wye
Rated kVA = 125 Rated kVA = 125
Voltage Ref = 480 V L-L Voltage Ref = 277 V L-N
(125 000 / 480) / 1.732 (125 000 / 277) / 3
= per Phase Rated Current = per Phase Rated Current
150 A = per Phase Rated Current 150 A = per Phase Rated Current
Example:
OVERCURRENT
LEVEL
180 A
180 A 180 A 180 A 180 A
Rated Current
150 A
150 A 150 A 150 A 150 A
Delay Time 0.1 s 1.0 s 5.0 s 10 s 20 s
AMP SECONDS
3.0
30.0 150 300 600
Actual Current 170 170 170 170 170
Trip Time
No Trip
No Trip No Trip No Trip No Trip
Actual Current 181 181 181 181 181
Trip Time
3.0 s
30 s 150 s 300 s 600 s
Actual Current 190 190 190 190 190
Trip Time
0.3 s
3 s 15 s 30 s 60 s
Actual Current 200 200 200 200 200
Trip Time
0.15 s
1.5 s 7.5 s 15 s 30 s
Actual Current 220 220 220 220 220
Trip Time
0.075 s
0.75 s 3.75 s 7.5 s 15 s
Table 4-1. Overcurrent Level Chart