Is the following sentence grammatically correct?
It is moved from location A to B.
If yes, then which tense is being used here? I'm not sure if a past tense can be followed by is.
The sentence is purely grammatical. It is in passive voice. The sentence is:
It is moved from location A to B by somebody.
By somebody is implicit in this sentence. So if I change it into active voice, it becomes:
Somebody moves it from location A to B.
According the rule of voice change, if the active voice is in simple present, the passive voice changes into the following construction:
Active voice: John makes a cup of tea. --> Passive voice: A cup of tea is made by John.
You can check out the voice conversion rules on STUDYANDEXAM.COM (Passive Voice for All Tenses Rules)
SUPPLEMENTAL to Mistu4u's ANSWER :
OP appears to be confused by the form moved. In this case the form does not represent a past tense but a past participle. In regular (weak) verbs, the two forms are identical, but they are used differently:
if the form heads the verb phrase, it is a tense and expresses completed past action. In the case of MOVE that action may be either transitive or intransitive:
He moved it from A to B. (transitive: it is the Direct Object and is the Patient of the action, acted upon by he, who is both Subject of the sentence and Agent of the action)
He moved from A to B. (intransitive: He, Subject and Agent, acts, but not upon another person or object)
if the form follows a form of BE or HAVE, it is a past participle:
if it follows a form of HAVE, the construction is perfect, designating a past action with relevance at the time expressed by the form of HAVE. MOVE may be either transitive or intransitive:
He has moved it from A to B. (transitive, present perfect: the action was in the past but is still relevant in the present)
He had moved from A to B by 1964. (intransitive, past perfect: the action took place before 1964 but was still relevant in 1964
if the form follows a form of BE, the construction is passive; the Subject of the construction is the Patient of the action, and the Agent is either not specified or is specified in a separate phrase. In this case MOVE can only be used in a transitive sense.
This is the case involved in OP's question and Mistu4u's answer.
Note that it is possible for moved to be preceded by both a form of HAVE and a form of BE, creating a perfect passive construction. In this case it is HAVE which is inflected for person and tense, and the past participle of BE is employed: been.
It has been moved from A to B.