The main causes of voltage drop in generator

Some common reasons are :
1). Load applied to generator exceeds capacity, typically would cause machine to slow down, drop frequency and voltage typically cause exhaust black stacking and depending on the overload and protection settings could cause machine to stall.

2). AVR Voltage gain set too low to respond to load being applied.

3). If AVR feedback is from generator bus VT and voltage dips too far, all excitation could be lost and would typically result in an undervoltage and overcurrent trip.

4). Speed control gain set too low to respond to load being applied.

5). Mechanical issue such as failing turbo unable to provide enough air of high enough pressure while taking on load which will cause machine to slow down and in some cases stall on high load application with sufficient reduction in speed voltage will also lower as well as frequency. In this condition you'd probably also see exhaust black stacking.

6). Mechanical issue such as fuel injection clogged or fuel filters clogged causing the machine to be under fuelled to handle load application and may cause machine to slow down, which in turn would drop Hertz and Volts.

7). There's a whole truck load full of other reasons why this could happen.


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9/8/2016 5:14 PM
Thank you sir can any electrical appliances causes low voltage from thecgenerator
9/14/2016 5:03 AM
What is the probable causes that frequency not come up after geneator start.
9/15/2016 9:20 AM
Thanks for the information....
9/18/2016 6:35 AM
Hello All,
I have a three phase connection for my duplex house and hence the ACCL was badly burnt due to sudden surge from Electricity pole. Hence as the cost of the ACCL was high I replaced with a manual Changeover switch. But the output is not controlled and as it is direct from the generator, due to fluctuations in the Generator output My appliances are blowing out one by one due to uneven voltage. Five LED tubelights, microwave was burnt though not switched on, and many other appliances are burning out. Hence I have now disconnected the Generator supply to my house.

Any suggestions how to control Generator output fluctuations as it is directly from generator to my house.

My email Id is

Please provide cost effective solution.
Thanks in advance.
10/3/2016 3:35 PM
Thank you the information.
10/6/2016 6:49 AM
During engine idle operation the generator start hunting l.e hnmmm, hnmm and all the control signal will lost. As result it shortdown on underfrequency. Pls what is the caues for this?
10/15/2016 5:09 AM
Every now an then my genartor the volts will drop an only put ut a lil power I was messing wid plug wigglein it an it started work good but every now an then it will drop any ideas
10/20/2016 7:03 PM
I have a model 40008 champion generator that at times it drop voltage. This could last maybe 5 minutes or as much as several hours. I really don't want to get rid of it as it was my brothers.
10/23/2016 2:10 AM
My generator not giving any output power
11/10/2016 10:40 PM
my 3000 series Shrewsbury is over speeding and I don't now what to du
11/11/2016 5:08 PM
I have an opposite effect on my Volvo 580KVA generator. When almost 40% of the full load is removed from the generator in one step, not only there is no voltage overshoot, but, on the contrary, the votage drops from 380V down to 320V momentarily before recovering.
This is a peculiar beaviour and I have not found a solution. The load removed is a motor (inductive load) running on a soft starter.
Any suggestions?
11/14/2016 11:37 AM
i have a 3 phase stamford generator run by perkins engine. the generator trips on undervoltage while on load. what might be the cause?
11/20/2016 12:49 AM
Dear sir .when we start generator .some time start properly but some time .stop due to .(common voltage/frequency fault alarm )if running 2 o 3 days suddenly stop for this alarm .any solution sir.thanks
11/21/2016 9:21 AM
when a diesel generator developed such fault (voltage drop), which of the causes do we need to start from?
11/21/2016 6:53 PM
Can faulty capacitor cause voltage/current drop
11/21/2016 9:43 PM
Hallow can you assist me with this I have may generator giving the error of over ac volt . What could the problem
12/4/2016 7:21 PM
my diesel generator will shut down while running and will display an alarm abnormal acb trip, what are the causes why my acb will trip while the load at 70 percent?
12/18/2016 6:20 AM
If I plug my laptop to my little generator the power would drop but if removed it come up why.
Please I need your help
12/29/2016 2:36 AM
We have a 10kw/43 A / 230V single phase A.C Brush Generator which works properly when there is no load or low loads (less than 10 A) but when we connect more loads to the output, the voltage suddenly drops ( it goes down to 30 V). What can be the reasons?
12/29/2016 2:46 AM
What type of loads are you trying to connect? If they are highly inductive or involve any type of high inertia loads, then your generator may not be able to provide enough starting torque or voltage support to successfully start them.

Low power single phase alternators often have simple excitation systems that use the output of the alternator to provide the field current, and are incapable of supplying high inrush current loads.

Small generators like this draw their excitation power from the output of the generator, have no AVR, nor any Boost capability; i.e., their voltage falls as the load increases. The size and type of load makes a huge difference in the generator's ability to maintain the voltage in an acceptable range when equipped with a simple excitation system that operates open loop.

Where did the excitation power come from, the generator terminals, or a dedicated extra winding in the stator? If it comes from the output terminals, then the "voltage regulator" is usually a LM part number whose job it is to limit the voltage to the field under no/light load, but it can do nothing to support the terminal voltage as it falls due to large inductive loads being applied.

A separately derived excitation source will indeed attempt to raise the excitation level to the current limits of the field/stator winding, but such sophistication is usually not found in consumer level single phase generators due to the cost factor.
12/30/2016 9:11 PM
During starting of emergency generator voltage drop from 440 to 220 or 200. What is the cause?
1/17/2017 3:02 PM
When generator with load voltage is going to reduce and sometime no load also voltage is going to low
what would be reason..
Give me any idea
1/24/2017 9:55 AM
I have Stamford generator
The problem was
Generator  no load and with load also voltage   is going down
From AVR I increase the voltage up to 385v. Still same no load also voltage is going
Frequency ok
What would be reason
Pls e mail me..
2/9/2017 8:45 AM
please can you explain how to set or fix gen low frequency and low volts
2/18/2017 2:11 AM
how can we rectify that can of problem sir
2/19/2017 1:42 PM
Pls. what can i do to my generator that has only 120V output to get 220V?
Thank you.
3/7/2017 3:59 AM
pls help a 2200 series Perkins, when loaded , the gen drops.

3/9/2017 12:16 AM
How about poor / contaminated propane? I have a 16KW LP genset- operated perfect for years (still runs great), BUT last time we lost power it kicked on, ran just fine, until a 220 circuit kicked on (water heater, clothes dryer - any 220V).  Then it "lugged down" and was working HARD to hold high RPM (which it failed to do) a result, nothing else 120v in the house was usable until the 220v circuit kicked back out. When the 220v load was removed, rpm went right back up, no more lugging and all 120v house things worked fine.
3/9/2017 2:07 AM
I should have mentioned (DUH) the post of mine above......  The reason I suspect bad propane is because the only thing that has changed on my entire house / system IS THE FACT THAT I HAD THE PROPANE TANK FILL 30 DAYS AGO and since then, our stove burners show orange flames at the tips and full length streaks of orange too......and our home (LP) heater seems to run LONGER to get the home up to temp each time the thermostat kicks the heat on.
3/9/2017 6:01 AM
when rain falls my ( VGF H24GL WAUKESHA.S/N C-17725/2 ) keeps shutting down and under frequency will show up, why is this?
3/12/2017 3:56 PM
I start my generator in the voltage fluctuates up and down the lights flicker trying to figure out why generator runs fine
3/31/2017 11:10 AM
i have a challenge with my generator it runs for only ten minutes,then drops voltage,how can i solve this

4/8/2017 5:07 PM
Siirr Please..!!! Give the Reason of voltage reduction of alternator on Load...?
4/8/2017 5:11 PM
Hello My Name is "Ubaid''
Sirr Please...!!!!
Give the Reason of voltage reduction of alternator on Load.

Give sOme important Reason's..

I Shall be very thankfull thankfulll.

MY Mail is :  (

4/10/2017 8:15 AM
but when i try to change the position of the main incomer breaker the voltage increases
4/14/2017 6:58 PM
I have
4/18/2017 6:05 PM
my generator 110 kva .. shutdown after High frequency with higher Tpm .. I adjusted fuel pump throttle after that also i am getting  same fault .. pls help me to get rid of from this breakdown
4/21/2017 5:53 PM
Thanks and useful information was learned by us...

Tahir Mohammad Hassan