{"id":39849,"date":"2026-01-08T11:05:16","date_gmt":"2026-01-08T11:05:16","guid":{"rendered":"https:\/\/calibration.consulting\/product\/mi-7070a-ac-ratio-bridge\/"},"modified":"2026-01-08T11:05:16","modified_gmt":"2026-01-08T11:05:16","slug":"mi-7070a-ac-ratio-bridge","status":"publish","type":"product","link":"https:\/\/calibration.consulting\/en\/product\/mi-7070a-ac-ratio-bridge\/","title":{"rendered":"MI 7070A AC Ratio Bridge"},"content":{"rendered":"

The MI 7070A AC Ratio Bridge is designed for fast, accurate and fully automated measurements of instrument transformers. The instrument forms the heart of modern AC metrology systems and offers an unrivalled combination of flexibility, accuracy and ease of use. Whether calibrating current transformers (CTs) up to 10,000 A or voltage transformers (VTs) up to 800 kV, the 7070A delivers reliable results with ppm accuracy.<\/p>\n

Designed for modern AC metrology<\/h3>\n

In high-voltage and high-current distribution systems, the accuracy of instrument transformers is crucial. Even small errors in CTs or VTs can lead to significant measurement deviations in energy and power measurements. The 7070A is designed to detect and quantify these errors with high precision, so that laboratories and utility companies can rely on correct and reproducible measurement results. The 7070A utilises 24-bit simultaneous sampling technology, enabling ratio and phase errors to be measured with a resolution of 1 ppm. Its stable phase response and low noise floor make the instrument suitable for both primary and secondary calibration applications.<\/p>\n

Three models for maximum flexibility<\/h3>\n

The 7070A series consists of three variants, each optimised for specific applications:<\/p>\n

7070A-I \u2014 AC Current Ratio Bridge<\/strong><\/p>\n

This model is designed for calibrating current transformers. With ten input current ranges from 0.004 A to 5 A, a single reference CT can be used to test CTs with a wide range of nominal ratios. Higher currents are achieved via external precision CTs such as the MI 7020 series. The 7070A\u2011I offers ratio accuracies of up to \u00b175 ppm and phase error accuracies of up to \u00b10.2 minutes.<\/p>\n

7070A-U \u2014 AC Voltage Ratio Bridge<\/strong><\/p>\n

This model focuses on voltage transformers and supports six voltage ranges from 6 V to 300 V. In combination with MI’s 2500 series high-voltage dividers and CG series standard capacitors, VTs up to 800 kV can be calibrated with a single setup. The 7070A\u2011U offers the same high ratio and phase error accuracy as the CT model.<\/p>\n

7070A\u2011UI \u2014 Combined AC Ratio Bridge<\/strong><\/p>\n

The 7070A-UI combines the functionality of both models in a single instrument. With four inputs and both current and voltage ranges, this model is ideal for laboratories seeking an all-in-one solution for CT and VT calibration. Optionally, the 7070A-UI can be expanded with a power measurement function, which also allows AC power and phase angle to be verified.<\/p>\n

Easy integration into measurement systems<\/h3>\n

The 7070A is designed for both standalone use and integration into complex measurement systems. Thanks to the GPIB interface, the instrument can be controlled by MI software or external automation platforms.<\/p>\n

MI supplies complete measurement systems based on the 7070A, including:<\/p>\n

> 7020 series standard CTs
\n> 7200 Series current comparators
\n> 2500 Series high-voltage dividers
\n> CG Series high-voltage capacitors
\n> Electronic burdens
\n> Complete PC-based automation<\/p>\n

This allows laboratories to build complete CT\/VT test setups with minimal configuration effort.<\/p>\n

Performance and accuracy<\/h3>\n

The 7070A offers performance that meets the highest industry standards:<\/p>\n

> Ratio accuracy: \u00b175 ppm (typical)
\n> Phase error accuracy: \u00b10.2 minutes
\n> Linearity: \u226420 ppm
\n> Frequency range: 15\u2013100 Hz
\n> Resolution: 1 ppm<\/p>\n

These values make the instrument suitable for both factory acceptance testing and national measurement institutes.<\/p>\n

Robust design and ease of use<\/h3>\n

The 7070A is housed in a sturdy 19-inch enclosure and weighs only 15 kg, making the instrument easy to install and integrate. The user interface is clear and provides direct access to ratio measurements, phase errors, reference settings and DUT parameters. The Measurements International 7070A AC Ratio Bridge offers a powerful, accurate and versatile solution for calibrating current and voltage transformers. Combining advanced sampling technology, flexible configurations and full automation capabilities, the 7070A is a future-proof choice for any AC metrology laboratory.<\/p>\n","protected":false},"excerpt":{"rendered":"

    \n
  • Ratio accuracy: \u00b175 ppm (typical)<\/li>\n
  • Phase error accuracy: \u00b10.2 minutes<\/li>\n
  • Linearity: \u226420 ppm<\/li>\n
  • Frequency range: 15\u2013100 Hz<\/li>\n
  • Resolution: 1 ppm<\/li>\n<\/ul>\n","protected":false},"featured_media":39848,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_acf_changed":false,"_seopress_titles_title":"MI 7070A AC Ratio Bridge","_seopress_titles_desc":"The MI 7070A AC Ratio Bridge is designed for fast, accurate and fully automated measurements of instrument transformers.","_seopress_robots_index":"","_seopress_robots_follow":"","_seopress_robots_imageindex":"","_seopress_robots_snippet":"","_seopress_robots_primary_cat":"none","_seopress_robots_breadcrumbs":"","_seopress_robots_freeze_modified_date":"","_seopress_robots_custom_modified_date":"","_seopress_robots_canonical":"","_seopress_social_fb_title":"","_seopress_social_fb_desc":"","_seopress_social_fb_img":"","_seopress_social_fb_img_attachment_id":0,"_seopress_social_fb_img_width":0,"_seopress_social_fb_img_height":0,"_seopress_social_twitter_title":"","_seopress_social_twitter_desc":"","_seopress_social_twitter_img":"","_seopress_social_twitter_img_attachment_id":0,"_seopress_social_twitter_img_width":0,"_seopress_social_twitter_img_height":0,"_seopress_redirections_value":"","_seopress_redirections_enabled":"","_seopress_redirections_enabled_regex":"","_seopress_redirections_logged_status":"both","_seopress_redirections_param":"","_seopress_redirections_type":301,"_seopress_analysis_target_kw":"","_seopress_news_disabled":"","_seopress_video_disabled":"","_seopress_video":[],"_seopress_pro_schemas_manual":[],"_seopress_pro_rich_snippets_disable_all":"","_seopress_pro_rich_snippets_disable":[],"_seopress_pro_schemas":[]},"product_brand":[],"product_cat":[249,250,260],"product_tag":[],"class_list":["post-39849","product","type-product","status-publish","has-post-thumbnail","product_cat-calibration-en","product_cat-electrical-calibration","product_cat-power-energy","first","instock","shipping-taxable","product-type-simple"],"acf":[],"_links":{"self":[{"href":"https:\/\/calibration.consulting\/en\/wp-json\/wp\/v2\/product\/39849","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/calibration.consulting\/en\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/calibration.consulting\/en\/wp-json\/wp\/v2\/types\/product"}],"replies":[{"embeddable":true,"href":"https:\/\/calibration.consulting\/en\/wp-json\/wp\/v2\/comments?post=39849"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/calibration.consulting\/en\/wp-json\/wp\/v2\/media\/39848"}],"wp:attachment":[{"href":"https:\/\/calibration.consulting\/en\/wp-json\/wp\/v2\/media?parent=39849"}],"wp:term":[{"taxonomy":"product_brand","embeddable":true,"href":"https:\/\/calibration.consulting\/en\/wp-json\/wp\/v2\/product_brand?post=39849"},{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/calibration.consulting\/en\/wp-json\/wp\/v2\/product_cat?post=39849"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/calibration.consulting\/en\/wp-json\/wp\/v2\/product_tag?post=39849"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}