場合は means "in the case that" or "in the event of". It sets up a conditional situation, often with a nuance of handling specific cases or exceptions. It's more formal and explicit than と or たら, and is commonly used in written instructions, notices, and polite speech.

You attach it to the plain form (dictionary form for present, past form for past), and for nouns you need の before 場合は. For な-adjectives, use な (e.g., 元気な場合は). It can be used with both affirmative and negative forms.

Unlike たら, which often expresses a natural consequence or sequence, 場合は emphasizes the situation itself. It's like saying "in the situation where...". When the result is a suggestion or instruction, it often pairs with てください or なければなりません.