User Guide
Installation Manual    ASCO 3ATS, 3ADTS, 3NTS, 3NDTS 
381333-406  ASCO Power Technologies  Page 7 
Troubleshooting 
Check in Numerical Sequence 
Problem 
1 Operation  2 Generator 3 Voltage 
For 3ATS & 3ADTS the engine-
generator set does not start when 
the transfer test button is pressed 
or when the Normal source fails. 
The outage must be long 
enough to allow for the 
feature 1C time delay plus 
engine cranking and starting 
time. 
Starting control must be 
in automatic position. 
Batteries must be 
charged and connected. 
Check wiring to the 
engine starting contacts. 
- 
For 3ATS & 3ADTS the transfer 
switch does not transfer the load 
to the emergency source after the 
gen-set starts. 
Wait for the feature 2B time 
delay. For immediate 
transfer, press the transfer 
button (bypass timer). If 
inphase transfer is active, 
wait for inphase condition. 
For 3NTS & 3NDTS press 
the transfer button. 
Is the generator 
accepted light on? 
Generator output circuit 
breaker must be closed. 
Generator frequency 
must be correct. 
Voltmeter should read at 
least 90% of nominal phase 
to phase voltage between 
transfer switch terminals EA 
and EC (or EL1 and EL2 for 
2 pole switches). * 
* There are factory settings. 
For 3ATS & 3ADTS the transfer 
switch does not transfer the load 
to normal source when normal 
returns or after transfer test. 
Wait for the feature 3A time 
delay. For immediate 
retransfer, press the transfer 
button (bypass timer). If 
inphase transfer is active, 
wait for inphase condition. 
For 3NTS & 3NDTS press 
the transfer button. 
- 
Voltmeter should read at 
least 90% of nominal phase 
to phase voltage between 
transfer switch terminals NB 
and NC, NC and NA, and 
NA and NB (or NL1 and NL2 
for 2 pole switches). 
For 3ATS & 3ADTS the 
generator does not stop after load 
retransfer to the normal source. 
Wait for the feature 2E 
delay. 
Starting control must be 
in automatic position. 
- 
For 3ADTS & 3ADTS the load is 
deenergized (off).  Load 
Disconnect Timer on display. 
Wait for the delayed-
transition transfer timer. See 
User’s Guide 381333-400. 
 - 
Not in auto light is always on. 
For 3NTS & 3NDTS this 
light is always on, indicating 
it is a manual transfer 
switch. 
- - 
Alert light is on. 
Read the display for more 
information. Refer to 
User’s Guide 381333-400. 
- - 








