Fuel Gas Heater operated by thyristor control panel causing fluctuating on feeder Ampere

[341968]

Dear Gents,
We have following thyristor control panel from CD Automation srl


MULTIDRIVE-3PH Thyristor Unit 1100A – 1400A 1700A-1900A-2100A

It is operating to a fuel gas heater (manufactured by Fati srl. 400V, 50HZ, 700KW, 1011.6A). It is working perfect. only the problem we are noticing the current fluctuation on the feeder Micro Logic Relay 2.0E. That is the input current to the thyristor control pane. Here under is our observation:
Thyristor panel dispaly CD-KP (Ampere) : 174 178 153 143 170 227 346 288 and corresponding Ampere on Micrologic 2.0E are
301 270 373 159 184 429 777 273
My question is why Micro logic is not showing almost same current as output current from thyristors to electrical fuel gas heater heater. Is it normal the input current of the thyristor control panel is always fluctuating. Your technical assistance shall be highly appreciated.

 

[davidbeach]

Any of a wide variety of things. Measuring different things over different time spans using different measurement algorithms seems like a good place to start. Comparing a meter showing RMS current against a meter showing fundamental current is a good way to get people excited about problems that may not actually exist.