The FG4K is a discontinued encoder series, and successor models have since been introduced. However, versions with a “V” suffix are still relatively easy to misidentify during replacement selection. In particular, if the electronic configuration associated with the “V” suffix is overlooked, the replacement encoder may be specified with the wrong pulse count, creating unnecessary work in procurement, commissioning, and field replacement.
First, it is useful to review the basic FG4K specifications. The series uses an approximately 115 mm flange and is commonly available with 11 mm and 14 mm shaft diameters. Differences between individual models are mainly related to pulse count, with common values including 1024, 2000, 2048, 2400, 2500, and 4096 PPR.
Some FG4K models carry a “V” suffix, for example:
FG4K-2400G-90G-NG-V, FG4K-2048G-90G-NG-V, FG4K-2500G-90G-NG-V, and FG4K-2000G-90G-NG-V.
For these models, the “V” suffix corresponds to an electronic pulse multiplication configuration. This is an important detail when selecting a replacement.
If the new encoder does not provide the same electronic multiplication function, it should not be selected simply by matching the pulse count shown in the original model number. Instead, the replacement needs to be matched according to the actual output after multiplication. For the FG4K “V” models discussed here, this generally means selecting a non-multiplied encoder with twice the nominal pulse count in order to maintain the same effective pulse output in the application.
For example, when replacing FG4K-2500G-90G-NG-V with an encoder that does not use the same multiplication function, selecting a standard 2500 PPR encoder would not be sufficient. The replacement should instead be matched to 5000 PPR based on the actual output relationship.
The principle itself is not particularly complicated, but matching errors still occur quite often in real procurement projects. In many cases, the mechanical dimensions and mounting are correct, while the pulse output is wrong because the multiplier function was overlooked.
Custom replacement solutions for these FG4K models are also available in China. These products are configured according to the actual application parameters of the original encoder, so the user does not need to calculate the multiplication relationship independently. In most cases, providing the complete original model number is enough for the supplier to determine the appropriate replacement configuration.
This type of custom replacement solution was originally developed several years ago by SIVIDI at the request of companies in the steel and metallurgical industries, mainly to solve practical replacement problems involving legacy FG4K models.
Whether using an original successor model or a custom replacement, it is important to confirm whether the original encoder includes electronic pulse multiplication. For FG4K models with a “V” suffix, this is often one of the easiest details to overlook during replacement.
Many of these encoders are sourced through cross-border procurement, sometimes involving several countries. If the wrong model is selected, reordering, transportation, and field replacement can create unnecessary cost and delay. For this reason, confirming the multiplication relationship and the actual pulse output before placing an order is often more important than simply matching the model number itself.
