What is indicated by an OL reading on a multimeter testing a transformer?

When a multimeter displays an OL reading while testing a transformer, it indicates an open circuit in the winding. This means that there is a break or disconnect in the transformer’s wire coils, preventing electrical continuity. As a result, no current can flow through the winding, which confirms that the transformer is not functioning properly.

In electrical terms, an open circuit occurs when the path for the current is interrupted, which is consistent with the OL (over limit) reading on the multimeter. A healthy transformer winding should produce a measurable resistance, typically within a specific range depending on the transformer specifications. The OL reading signifies that resistance is infinite, pointing directly to an issue within the windings.

Other scenarios such as a functional transformer would not yield an OL reading; instead, a proper measurement would show acceptable resistance levels. Similarly, incomplete circuits or short circuits would produce distinct readings that indicate different electrical conditions, making the OL reading specifically indicative of an open circuit in this context.